THE IMPACT OF A MODERATE EXERCISE PROGRAMME ON SERUM INTERLEUKIN-2

AND INTERLEUKIN-4 LEVELS AMONG SECONDARY SCHOOL CHILDREN

by

ARIMI FITRI BIN MAT LUDIN

Research Project Report Submitted In Partial Fulfilment Of The Requirements For The Degree

Of Master of Science (Sports Science)

Of

UNIVERSITI SAINS MALAYSIA

II

Supervisor : Assoc. Prof. Dr. E. T. Larmie Co-supervisor : Assoc. Prof. DR Ishak Bin Mat May 2001

Ill

A(~KN()WLEDG fi:J\·1 ENTS

Bisrnillahirrahtnanirrahirn. In the narne of Ood, Allah, The alrnighty and the rnost Merciful, thanks you God.

A very special thank to 1ny loving rnother Pn. Rusnani llj Hanm who always encourages tne, with her love and care which has 111ade it possible for 1ne to cotnplete 1ny dissertation. Also thanks to 1ny father., I ~n. Mat I ~udin Sen1an.

To 1ny supervisors, Assoc. Prof. Dr. E.T. Lannie, Assoc. Prof DR Harbindar Jcet Singh and Assoc. Prof. f)R Ishak Mat, thanks for all your dedication as supervisors. The only person, who can give rc\vard to you for your dedicated supervision, is God. I would also like to express 1ny gratitude to rny Sports Science Course Coordinator, Professor Rabindarjeet Singh for his support and guide throughout rny study in USM., Kelantan Branch. Not to forget, Head of Deparhnenl of Bio1nedical Sciences, Faculty of Allied Health Sciences, UKM, Assoc. Pro[ l)R Rahitn Noah this special thanks is extended to you also.

To all of n1y lovely brothers frotn Sck. Men. Sa ins Tcngku Mohatnad Faris Petra, ·who showed so n1uch dedication towards this project, I say thanks a lot boys, and also to Mr 1-Iatnzah, the principal Mr Mohd Noor and Mrs Ruziah, both teachers from SMSTMFP thanks for your assistance that was extended to 1nc during Jny study in your school.

Last but not the least, to tny course n1atc, Miss Farah, l)r Noor and En. Mat Saat., thanks for all of your encouragernent and advice.

TABLE ()If (~()NTI~NTS

CONTENT

ACKNOWLEDGE.I\'IEN'I'S

LIST OF TABLES

LIST ()F FJ<;URES

Lls·r OF API)ENI>ICES

LIS1' ()F ABBREVIATIONS ANI> SYI\IIJ()LS

ABSl"J{A(;·r

ABSl'RAI(

1.1 ,· 1.2 . 1.2.1 1.2.2

INTR()J)(J(:TI()N

Introduction Study Objective General Objective Spcci fie Objective

LITERATUI{E REVIEW

2. 1 The hntnune Sysletn 2. 1.1 Innate Inlsnunity 2. I. I. 1 Physiological and Chernical Barriers

2.1.1.2 Cellular Defence 2.1.1.3 Inflan1n1ation 2. 1.1.4 Biological Active Substances

2.1.2 Acquired llnmunily 2. 1.2. J T-cells 2. 1.2.2 B-cells

IV

PAGE

III

IV

VII

VIII

IX

X

XI

XIII

3 3

4 5 5 6

7 8

8 9 12

2.1.2.3 hnrnunoglobulin 2.1.2.4 Cytokine 2.1.2.4.1 Interleukin 2 (IL-2) 2. 1.2.4.2 I nterleukin 4 (I L-4)

2.2 2.2.1

Physical Activity Type of Physical Activity

2.3 Physical Activity and Its hnpact on The lnunune Systen1 2.3.1 Leukocytes Subpopulation 2.3.2 Neutrophil 2.3.3 Cytokine

2.4 Adolescence and Physical Activity

CIIAJ)'fER Ill ME.fiiODS ANI> 1\'IAl'ERIALS

3.1 Methods

3.1.1 Subjects Selection 3. 1.2 Expcrirnental Design 3.1.3 Exercise Protocol 3.1.3.1 Wann-up 3.1.3.2 Conditioning Phase 3.1.3.3 Cooling down

3.1.4 Fitness Assessrnent ~· 3.1.4.1 Hearl Rate · 3. 1.4.2 Blood Pressure 3.1.4.3 One-mile Run Test

3.1.5 Smnples Processing and Handling 3.1.5.1 San1ples Preparation

3. 1.6 Haernatology Test

3. I. 7 I ntcrleukin Measuren1ent 3.1.7.1 Reagent Preparation 3.1.7.2 Assay Procedure

3.2 Statistical Analysis

13 15 17 19

23 24

25 26 27 29

30

34

34 36 36 39 39 40

42 42 42 42

43 43

45

45 46 46

50

v

I

CIIAI'TER IV RESlJLTS

4. I Fitness Assesstnent 4. I. I One-tnile Run Test 4. 1.2 Resting Heart Rate 4. 1.3 Blood Pressure ( BP) 4.1.3.1 Systolic BP 4.1.3.2 Diastolic BP

4.2 l-Jaetnatology Test 4.2. 1 White Blood Cell ( WBt ~) 4.2.1.1 Total WBC 4.2.1.2 Leukocytes 4.2.1.3 Monocytcs 4.2.1.4 Granulocytes

4.2.2 Red Blood Cell (RBC) 4.2.2.1 RBC Count 4.2.2.2 I laen1oglobin Concentration 4.2.2.3 lletnatocrit

4.3 lnterlcukin (IL) Level 4.3. 1 I L-2 4.3.2 IL-4

CIIAPTER V DIS<~lJSSION

· (:IIAI''fER VI C()N(~LlJSI<>N

BIULIO(;J{AI)I·IY

Al)l~NIJJ(:ES

51 51

54 54

56 56 56 57 57

59 59 59

61 61

63

70

71

80

VI

VII

LIST ()F TAIJLES

NO PAGE

Table 2.1 Major T-cell subsets found in nonnaJ blood and peripheral tissues II (Parslow, 1997)

Table 3.1 Jogging prograrnme (Robbins et ul., 1999) 38

Table 3.2 Borg's Rating of Perceived Exertion (Robbins et al., 1999) 41

Table 4 .I Total and di fTerential white blood cell counts of the 35 subjects 58

VIII

LISrf <>F FIGURES

N<> PAGE

Figure 2. I The numerous functions of cytokines in imtnune system 21

Figure 2.2 The interrelationship between innate and acquired itntnunity 22

Figure 3.1 Blood sa1nple processing 44

Figure 3.2 Summary of the IL-2 assay procedure 48

Figure 3.3 Summary of the IL-4 assay procedure 49

Figure 4.1 One-tnile run test result for the pre- and the post-exercise 52 prograrn1ne (1nean ± SEM). * significant ditTerent fron1 the pre­exercise value at p<0.05.

Figure 4.2 Resting heart rate for the pre- and the post-exercise progratntne 53 (mean± SEM). * significant different fro1n the pre-exercise value at p<0.05.

Figure 4.3 Systolic and diastolic blood prcssu1e ( BP) of the subjects for the 55 pre- and the post-exercise progran11ne ( 1nean ± SEM). * significant different from the pre-exercise value at p<0.05.

·~ Figure 4.4 Red blood cell count and its cotnponent (anean ± SEM for the 60 pre- and the post exercise progran11ne. *significant different fro1n pre-exercise value at p<0.05.

Figure 4.5 IL-2 level of the subjects 62

IX

LIST OF APPENDICES

NO PAGE

Appendix A Physical activities questionnaires 80

Appendix B Consent forrn of the subject 83

Appendix C Consent fonn of the parents or guardian 86

Appendix D Approval from Ministry of Education 87

Appendix E Approval fro an State Education Departrnent of Kelantan 88

X

LIST <>F ABBREVIATI<>NS ANil S\'1\'IBOLS

IL interleukin % percentage ~d micro litre BMI body rnass index BP blood pressure CD cluster or differentiation CSF colony stirnulating factor dl decilitrc g gratn G-CSF growth-colony stin1ulating factor IIDL high-density lipoprotein IFN interferon Ig i mtnunoglobul in [) Dalton kg kilogran1 L litre Lf)L low-density lipoprotein M tnolar MI-ll{ rnaximum heart rate m1n. minute tnl tnillilitre tntn tnillin1etrc rnRNA messenger ribonucleic acid MW molecular weight

,·NK natural killer ·NcJ nitric oxide (lc degree Celsius

PE physical education

pg picograrn

PHA phytohernaglutinin A

PMN polymorphonuclear

RBC red blood cell RES retikuloendothel ial systern RJIR resting heart rate rpm rate per rninute SEM standard error of n1can THR target heart rate TNF tutnor necrosis factor V()21nax 1naxitnal oxygen power~~uptake WBC white blood cell

TliE IMPACT OF A 1\'IODERATE EXERCISE I)ROGRAMME ON SERU~IINTEitLEUKIN-2 AND INTERLElJKIN-4 LEVELS

AMONG SJ~(~ONDARY S<~IIOOL CHILDREN

ABSTRA(:T

XI

Cytokines are soluble glycoproteins that mediate cotntnunication between and within

imn1une and non-imtnune cells. An alteration of cytokine production will impair the

i1nrnune response and function. Previous studies on the itnpact of exercise on cytokines

have not been conclusive. Most studies were centered on adults and there is a lack of data

about the correlation between exercise and cytokines on adolescents. The purpose of this

investigation therefore, was to detennine the effect of tnoderate exercise on some

cytokine levels in adolescence.

Thirty five (n=35) physically inactive 16 year old boys were recruited and subjected to a

tnoderate exercise, 60 - 75% of 1naxHR, 40 - 60 tnin. duration, 3 times/week, for eight

~· (R) \veeks. They were subjected to the fitness test ( one-tnile run test) also 10 ml of blood

was drawn for differential count and the serutn (50 Jll) for IL-2 and IL-4 analysis using

ELISA for both pre and post-exercise progra1nn1es. Data collected were analysed by the

Student's paired t-test.

There was 110 significant difference in scnnn I L-2 and I L-4 levels as well as in total and

differential white blood cell counts. llowever, there were significant (p<0.05)

improvements in the one-tnile run tests. (9.07 ± 0. 11 tnin. vs. 9.0 I ± 0.11 n1in. ) .. resting

heart rate (68.63 ± 0.42 beats/tnin. vs. 64.83 ± 0.29 beatsltnin. ), blood pressure ( 115.00 ±

XII

1.47 tnmflg vs. 110.77 ± 1.36 rnmHg for systolic and 68.26 ± 1.15 mmHg vs. 67.17 ±

0.97 mml-lg for diastolic), RBC count (5.00 ± 0.06 x 109/1 vs. 5.14 ± 0.06 x 109/1)~

haemoglobin concentration ( 14.35 ± 0.15 mg/d1 vs. 14.63 ± 0.15 tng/dl) and haematocrit

(42.20 ± 0.42% v.s. 42.95 ± 0.39).

The study indicates that tnoderate exercise progran11ne could itnprove the fitness level in

the adolescent with no alteration in IL-2 and IL-4 levels.

XIV

mn1Hg vs. 67.17 ± 0.97 1nml--lg bagi diastolik)~ bilangan sel darah merah (5.00 ± 0.06 x

1 09/l vs. 5.14 ± 0.06 x I 09/1)~ ketun1patan hernoglobin ( 14.35 ± 0.15 tng/dl vs. 14.63 ±

0.15 mg/dl) dan he1natokrit (42.20 ± 0.42% vs. 42.95 ± 0.39).

Kajian ini rnenunjukkan senarnan pada intensisti sedcrhana yang diikuti~ mampu

tneningkatkan status kecergasan retnaja tanpa kecelaruan pada aras IL-2 dan IL-4 serutn.

CIIAPTER I

INTRODlJ(:TJ()N

1.2 INTR(JDUCTJ()N

Epidetniological evidence has shown that regular exercise increases the immune

function while strenuous exercise leads to imtnune suppression (Pedersen & Toft~

2000). Accurnulating facts have shown that regular exercise offers some protection

against malignancy at an early stage of life (Pedersen & Ton~ 2000). In this regard~

cytokine released into the circ~lation have been in1plicated as a causative tnediator of

exercise-induced itntnunc perturbation. Suzuki and his colleagues (2000) did a study

on rnarathon runners and reported a significant increase in the concentration of IL-2

· while a significant decrease in IL-6~ -8 and -I 0.

Cytokines play a 1nultifunctional role in the in1n1une syste1n. They rnediate

cotntnunication between and within i1nrnune and nonirnrnune cells. They play a major

role in initiating the itntnune responses. lienee, alteration or perturbation in cytokine

regulation 1nay produce to a tnarked itnpact on the itnrnune systern. This tnay lead to

an increase in susceptibility to infection by tnicroorganistns that will irnpair the

individuars life.

2

The beneficial effects of exercise are very well accepted. Exercise needs to be

started frorn an early age of life and throughout ones life span. Consequently, the

habit of doing exercise needs to be pron1oted earlier especially throughout school life.

The itnpact of exercise on adolescents and its beneficial effects on health has

been a focus of recent research (Murray~ 1994 ). Regular exercise is presumed to play

a 1najor role in preventing several leading degenerative diseases of tnodern societies.

The United States Departrnent of Health and llutnan Service ( 1992) noted that

childhood is a critical tirne for developing healthy altitudes and behaviour patterns in

relation to tobacco use~ diet~ physical activity and other health-related behaviours that

tnay persist into adulthood (Fiectcher et a/., 1996 ). The proper atnount of exercise is

presutnably itnportant for the optin1al developrnent and health status of children. Too

tnuch or too little exercise 1nay have son1c adverse effects (McKeag, 1991 ).

In a recent survey, of more than 13 000 teenagers, only a third said they were

moderately to vigorously active five or rnore tin1es per week (Gordon-Larsen et al.,

J 999). A study by Sallis & McKenzie in 1991 of 759 children who took achievernent

test after three different physical interventions~ found that students in a health-related

physical education (PE) progratn did as well acadetnically as students who spent half

as rnuch tirne each week in PE.

Consequently, there is a need to focus on the i1npact of exercise on the

i1n1nune system in adolescents. There is a paucity of data about this particular issue in

Malaysia. I Ience, the present study is designed to detennine the effect of moderate

exercise on the itnn1une system of adolescents with special reference to cytokines.

3

.1.2 STUDY OB .. JE(~TIVE

As described above, physical exercise whether acute or chronic, moderate or

strenuous affects the inunune systen1. Most previous studies done were focused on

athletes or adults. I Iowever, no such studies have been done on Malaysian children in

secondary school. The purpose of this study~ theref()re, is to detennine the effect of

exercise on the itnrnune systetn of children.

1..2.1 GENERAL OBJECTIVE

To determine the cHccts of exercise on the i1n1nune systcrn in secondary school

children.

1.2.2 SPECJJ4JC ()B,JECTIVE

To detern1ine the effect of a n1oderate exercise progrmn on IL-2 and IL-4 levels in

secondary school children.

LITI~RATlJRE ltE\'IEW

2.1 TilE IMMlJNE SYSTEM

hntnunology is a branch of bio1nedical science concerned \vith the response of an

organistn to antigenic challenge, recognition of seiC nonself, all biological,

serological, physical and chemical effects of inunune phcnotnena (Dorland~s Medical

dictionary, 1995). The tenn itntnunity refers to all the tnechanisn1s used by the body

as protection against environtnental agents that are foreign to the body ( Benjatnini et

al., 1996).

The study of in11nunology as a science or subspecialty of biology has gone

through several periods of quiescence and active development. The itnmune syste1n

of our body can be divided into two categories, innate itnmunity and acquired

itntnunity.

5

2.1.1 INNATE IMJ\'IUNITY

Innate i1nn1unity are all the eletnents with which an individual is born with and which

are ahvays present and available at very short notice to protect the individual from

foreign invaders. These eletnents include body surfaces and internal con1ponents

( Benjamini et a!., 1996 ). The internal cotnponents can be further subdivided into two

subgroups, hmnoral and cellular parts. The hmnoral con1ponent include the

Jysozyn1es, cornpletnents~ acute phase proteins while the cellular component include

polyn1orphonuclear (PMN) cells, 1nacrophages~ 1nicrogial cells and natural killer

(NK) cells (Parslovv', 1997)

2.1.1.1 I,JJYSIOLOGICAL AND (]Jl~MJ<:AL BARRII~IlS

i) Skin

Skin is the first barrier against any 1nicrobial agents. Most of the microorganistns and

foreign substances cannot penetrate the hwnan skin~ unless there are damages.

However, so1ne can still enter through the sebaceous glands and hair follicles. Under

such condition, acids.. fatty acids and enzytnes in 1he sebaceous glands act as

antitnicrobial agents (Parslovv, 1997).

ii) Mucous

Mucous acts as a trap to foreign bodies. It co\'ers the surfaces of tnany areas in the

body such as the gastrointestinal and the res pi ralory tracts. In the gastrointestinal tract,

the presence of a low pi I, proteolytic cnzytncs and bile acid serve as protection

6

against bacterial infection. A sirnilar function is also served by the low pH of the

vagina (Parslow~ J 997~ Benjatnini el a/.~ 1996 ).

2.1.1.2 CELLULAR DEFENSE

i) Mechanisan of cellular defense

When an invading n1icroorganis1n has penetrated the vanous physiological and

chemical barriers, various types of specialized cells act as a line of defense and

destroy the invading microorganisrn by phagocytosis or killing it extrace11ularly.

ii) Cells involve with body defense

a) Polyrnorphonuclear (PMN) cells

PMN cells include such cells as neutrophils, basophils, eosinophils and tnast cells.

They function by ingesting and destroying invading foreign particles. When the

invading particles are detected by the phagocytic cells, they engulfed the foreign

invader and destroy it with enzytnes called lysozyrnes (Parslow, 1997).

b) Macro phages

Macrophages originate frotn rnonocytes in the blood. They served as phagocytic cells.

When 111acrophages enter the blood streatn as tnonocytcs, they rnigrate to various

parts of the body and then differentiate into specific and different cells. These include:

differentiation into reticuloendothelial systc1n (RES), Kupffer cells in the liver,

alveolar macrophages in the lung and a~ anicrogial cells in the nervous syste1n

(Parslow, 1997; Weir & Stewart, 1997).

8

2.1.1.4 BIOLOGICAL ACTIVE SlJBSTAN(~ES

Many tissues synthesize substances that arc hannlul to tnicroorganistns. Exatnples of

these are~ degradative enzytnes~ toxic fi·ee radicals~ growth inhibitors, acute phase

proteins and interferons.

2.1.2 A<~QUIRED IMl\'llJNITY

Acquired i1n1nunity is more specialized and suppletnents the protection provided by

innate itntnunity. Acquired itntnunity, in evolutionary tern1s, catne into play relatively

late, and is present only in vertebrates.

Elernents that participate in acquired in11nunity show specificity against

foreign agents in contrast to innate in1n1unity. The response in acquired i1n1nunity is

greater and faster as co en pared to innate itntnunity ( Be~jatnini el a/., 1996 ).

An acquired itntnunity can be subdivided into two cotnponents., involving two

types of cells. There are the lytnphocytes, T-cells and B-cells as well as two hutnoral

cotnponents, itntnunoglobulins (lg) and interlcukins (IL) (Weir & Stewart, 1997).

A nonnal adult hmnan body hac:: about a trillion lytnphocytes. The T- and B­

lineage cells arise frotn a subset of hac tnatopoietic sten1 cells in the bone tnarrow or

foetal liver (Weir & Stewart, 1997). A typical lytnphocytes is a stnall, round or club-

shaped cell, 5-12 ~un in dian1eter with a roughly spherical nucleus, densely con1pacted

9

nuclear chron1atin and a cytoplasrn so scanty as to be scarcely detectable under the

light tnicroscope (Bet~atnini eta/., 1996 ).

There is considerable evidence for the existence of a con1mitted marrow

progenitor, called the lytnphoid stetn cells, that serves as a cotntnon precursor for both

T- and B-cells. The progeny of this stern cell undergoes different pathways of

maturation to beT orB-cells ( Benjmnini eta/., 1996: Roitt eta/., 1989).

2.1.2.1 T-CI~LLS

The T-cells account for about 75o/o of all lytnphocytes. This group of lyrnphocytes

developed from an itnmature precursor cells that leave the •narrow and travel through

the blood streatn to the thytnus. In the thyrnus they tnature and becorne tnature T­

cells. These thytnus-derived cells are the source from vvhich the word T lymphocytes

are derived (Weir & Stewart, 1997).

i) Site of rnaturation

The tnaturity of T lytnphocytes occur rnainly during f()etal developtnent and for a

short titne after birth. Removal of thr thytnus gland in the neonate results in a severe

reduction of the quantity and quality of the T lyntphocytes. However~ retnoval of the

thymus in an adult results in a less · 11desircd affect, since the T lymphocytes have

already matured and populated the secondary lyrnphoid organ ( Roitt eta/., 1989).

10

ii) CeiJs types

a) T -lyrnphocytes

T-ce11s can be classified into two subsets known as CD4 and CD8. Mature and

functional T-cells always express either one of these surface proteins. The cells that

express CD8 have the capability of being cytotoxic or the ability to kill target cells.

CD8 T-cells is synonyn1ous with Tc cells or cytotoxic T-lymphocytes (CTLs) and

they play a rnajor role against viral infection (Weir & Stewart, 1997).

The T lyrnphocytes that express CD4 protein on their surface are known as T­

helper cells. Helper cells, CD4 T-ly1nphocytes, do not have cytotoxic capability but

instead function as helper T -cells (T11 cells). Roughly, 70°/o ofT-cells in hutnan blood

arc CD4 '·cos- (equal to CD4 cells) whereas 25°/o are CD4-CD8' (CD8 cells) the

remaining 5% form double posi1ive or double negative (CD4+CI)8+ or CD4-CD8-)

(Table 2. 1, Benjarnini et a/.., 1996 ).

T-lytnphocytes detect foreign bodies hy way of surface proteins called T -cell

receptors. These receptors are not secreted into the blood strearn, hence T-cells lack

the ability to strike at long distance targets (Weir and Stewar1, 1997).

T-cells can detect foreign bodies only by rnaking a specific contact and after

the foreign substances are cleaved into sn1all pcptides. This cleavage is carried out by

the so called antigen-presenting cells ( Bet~jfltnini et a/., 1996 ).

II

]'able 2 .. 1: Major T --cell subsets found 111 nonnal blood and peripheral tissues

(Parslow, 1997).

SURFACE PREIJ()MINANT PROP()RTJ()N ()F RECEPTOR

PHENOTYPES FUNCTJ()N TOTAIJ TYPE

L YMPIIOCYTES

co41- cos- I Ieiper 70% alp

CD4-CD8 .. Cytotoxic 25% a./p, rarely yo

co4-cos- Cytotoxic 4% ylo

CD4+CD8 .. Unknown 1 o/o a/(3

12

2.1.2.2 8-CELLS

The n1njor difference and defining feature of cells in the B-cell lineage is their ability

to produce imrnune protein called inununoglobulin., \vhere no other single cells

produce this protein. In ernbryonic life, B-cells differentiate fro1n haetnatopoietic sten1

cells in the liver. Aller birth and the rest of the lnnnan life., this function shifts into the

bone •narrow. The bone tnarro\v is considered as a pritnary lytnphoid organ that is

equivalent to the Bursa of Fabricius (DeFranco., 1 997).

All tnature 8-lytnphocytes express antigen specific receptors that have a

structure and specificity identical to the antibody. The tnature B-cells are transported

to the secondary lyrnphoid organ by circulating blood. During the transfer., when they

encounter a foreign antigen, they are activated and respond to it. When an activated

8-cell divides, so1ne of its progeny bccotnes 1netnory B-cells while the rest will

differentiate into plastna cells (DeFranco., 1997~ Benjatnini eta/., 1996).

The rnain function of 8-lincage cells is to secrete antibodies into the blood and

other body fluids thereby making these fluids inhospitable for foreign invaders. They

are the principal cell types involved in hutnoral itntnunity. B-cells also function as

antigen-presenting cells and as a source of lymphokines. These are itnportant

tnediators that are involved in cell tnaturation and itntnune response (I)eFranco ..

1997).

13

2.1.2.3 ll\'ll\1lJNOGL<lBULINS

llnrnunoglobulins are globular protein that serves as critical ingredients at every stage

of hutnoral imtnunity. There are two types or inununoglobulins:

i) lrntnunoglobulin expressed on the surface of resting B-lymphocytes that serve

as receptors

ii) hntnunoglobulins that are secreted into circulation to function as antibodies.

(Parslow, 1997~ Weir & Stewart, 1997)

The irnmunoglobulins are a related farnily but nonidentical glycoproteins. The

biologic attributes of imrnunoglobulins are detennined by its polypeptide components.

Secreted i1ntnunoglobulins, known as antibodies are bifunctional n1olecules in that

they bind specifically to antigens and also initiate a variety or secondary phenomena

such as activation of cotnpletnent, opsonisation or signal tranduction.

Every irnmunoglobulin tnolecule is tnade up of two different types of

polypeptides, the larger, heavy (II) chains and smaller~ light (L) chains. The chains

are held together by noncovalent forces as well as covalent interchain disulfides

bridges to fonn a bilaterally sy1n1netrical structure. All light chains proteins have a

molecular weight of approxirnately 23 000 D and can t}e classified into two distinct

types, called kappa (K) and larnbda (A). ()n the other hand~ heavy chains proteins have

a molecular weight of about 50 000 to 70 000 I.l There are also five different classes

or isotypes (Parslow, 1997).

14

The five classes of the heavy chains polypeptides are designated Jl, B, y, a. and

E and imtnunoglobulins that contain these heavy chains are designated the IgM, lgD,

IgG~ IgA and lgE respectively (Parslow, 1997)

i) hntnunoglobulin 0 (lgG)

JgG act ounts for approxin1ately 75% of the total sennn itntnunoglobulin in normal

adults and is the tnost abundant antibody produced during secondary intmune

responses in the blood. lgG is the only in1n1unoglobulin that can cross the hu1nan

placenta and it is responsible for providing the newbont \Vith protection during the

first rnonth of life (Parslo\v~ I 997: Berliatnini eta/., 1996).

ii) lmtnunoglobulin A ( lgA)

IgA is the predominant immunoglobulin produce by B-cells in Peyer's patches, tonsils

and other subanucosat lyanphoid tissues. It accounts for only 10 to 15% of total serutn

itnmunoglobulin, it is by far the tnost abundant class of antibody found in sativa,

tears, intestinal mucus, bronchial secretion, tnilk, prostatic fluid and other secretions

(Parslow, 1997)

iii) ltntnunoglobulin M ( lgM)

fgM constitutes about I 0~,~ of nonnal serutn irnrnunoglobulin and it is nonnally

st ~·reted as J-chain-containing pentatner with a n1olecular tnass of approximately 900

kD. IgM pn'dOU' :Hltcs in early prin1ary itnrnune responses to tnost antigens. I gO often

accotnpanies fgM. l'hese are the tnost conunon itntnunoglobulins expressed on the

surface of the B-cells~ particularly virgin 13-lymphocytes (Parslow., 1997; Weir &

Stewart, I 997).

15

iv) hnrnunoglobulin D (lgD)

JgD tnolecule is a tnon01neric four-chain unit with a rnolecular mass of approximately

180 kD and comn1only found on the surfaces of B-lyn1phocytes. It is rarely secreted

in significant arnounts. The physiologic function of lgD is still unknown. It is

relatively labile and is easily degraded by heat or proteolytic enzyrnes (Parslo\:v, 1997~

Weir and Stewart, 1997).

v) Itnmunoglobulins E (lgE)

lgE represents only a 1ninute fraction of all serutn antibodies, lgE is extrernely

itnportant from a clinical standpoint because of its central involveanent in allergic

reactions (Parslow, 1997).

2.1.2.4 CYTOKINES

All co1nmunicati9ns need a medimn to transfer the infonnation. In the body, the

mediurn is through chernical rnediators. In the irntnune system most of the critical

interaction arnong cells is controlled by soluble tnediators called cytokines.

The cytokines are a diverse group of intercellular-signaling proteins that

regulate local and systernic irn1nune response, infla1n1natory response, wound healing,

haernatopoiesis and 1nany other hiP :ogical processes (C)ppenhei•n & Ruscetti, 1997).

Benjarnini eta/. ( 1996) defined cytokines as antigen-nonspecific soluble factors.

There are over I 00 structurally different and genetically unrelated cytokines

that have been identified. These are polypeptides or glycoproteins with 1nolecular

16

weight (MW) of 6000 to 60 000 D. These n1ediators are highly potent and act by

binding to specific surface receptors at concentrations of I o-lJ to 1 o- 15 M. Most of the

cytokines act either as paracrine or autocrine. They are not produced by a specific

gJand like endocrine honnone but they are produced by a variety of different tissues

and individual cells (Oppenhein1 & Ruscetti~ 1997).

Most of the activities of cytokines are redundant or extensively overlap. One

cytokine tnay induce the secretion of another cytokines. Due to the redundancy and

complex interactions, it is quite perilous to extrapolate frotn an in-vitro study of

cytokines and use it to assess its role in an intact organisn1 (Moldoveanu et a!., 200 I~

Oppenheian & Ruscetti, 1997).

Cytokines non1enclature has little to do with structural relationship atnong

tnolecules. Cytokines produced by lyn1phocytes are known as lyanphokines, whereas

those produced by monocytes or tnacrophages are called tnonokines. Some of thetn,

known as interleukins (IL)~ have been assigned numbers in sequence from IL-1 toIL-

16. Many of the rest of the cytokines still retain their descriptive and frequent

tnisleading historical natne (()ppenheian & Ruscetti~ 1997).

Cytokines act over both short and long range~ \Vith consequent systetnic

effects. They play a crucial role in atnplification of the itnmune response. The release

of cytokines from just a few antigen-activated cells results in the activation of

tnu1tiple different cell types ( Moldoveanu eta/., 200 I).

17

2.1.2.4.1 INTERLElJKIN 2 (IL-2)

lnterleukins belong to the cytokine groups. lnterlcukins are referred to as cytokines

that are produced by one type of leukocyte and aflect other leukocytes. IL-2 is an

autocrine and paracrine growth lactor that is secreted by activated T-cells and is

essential for clonal T-cell pro I i feration.

IL-2 n1olecule is a polypeptide, that is n1ade up of about 133 amino acids and

has a molecular weight of 15 400 D. It is encoded by a single gene on the hun1an

chrornoso1ne 4. Its aanino acids sequence shows no sitnilarity with any other known

cytokine. It can be also glycosylated to tnultiple degrees to produce higher molecular

weight species. IL-2 is a globular protein with two alpha (a) helices that are arranged

to fonn hydrophobic planar faces around a very hydrophobic core. This configuration

is 1naintained in part by a single interchain disulfide bond. that is essential for biologic

activity (Oppenhein1 & RusceUi, 1997: Bet~atnini et al .. 1996 ).

I L-2 is one of the most critical inununoregulatory cytokines that is essential

for the T-cell proliferation. It affects cytokinc production and the functional properties

of B-cell, rnacrophagcs and NK cell' (()ppenhcitn & Ruscetti, 1997: Weir & Stewart,

1997).

Resting T lytnphocytes do not ~, · i hesize or secrete I L-2 but can be induced to

do both by an appropriate cotnbinations of antigen and <.:n~ti1nulatory factors or by

exposure to polyclonal tnitogens. Antigen-induced 11,-2 production occurs 1nainly in

18

CD4 Tn cells. CD8 lytnphocytes and some NK cells can however, also be induced to

secrete IL-2 under certain conditions (CJppenheirn & Ruscetti, 1997~ Weir & Stewart,

1997).

I L-2 has a very dorninant efTect on T-cclls. When nonnal hurnan T

lyrnphocytes are exposed to a T-cell 1nitogen, IL-2 tnRNA expression becotnes

detectable atler f()ur hours, reaching a peak after twelve hours and then declines

rapidly ( Moldoveanu eta/., 200 I).

IL-2 also has an effect on NK cells. The unique characteristic of NK cells is

that they express the I L-2 receptor (IL-2R) on its surface. This enables NK cells to

response to I L-2 even during their resting state. l hnvcver~ this response is weak. ()nee

NK ceiJs have been activated., they express the II ,-2(t chain. This requires a high

affinity receptor unlike that of its resting state. I L-2-stirnulated NK cells have

enhanced cytolytic activity, secrete nmnerous cytokincs, including interferon gatntna

(IFNy) and turnor necrosis factor alpha (TNFu). These are potent activators of

1nacrophages. IL-2 also induces lyrnphokine-activated killer (LAK) activity that is

predorninantly due to the NK cells ( Moldoveanu et a/., 2001: Oppenheirn & Ruscetti

1997~ Bcnjamini eta/., 1996 ).

()n the other hand~ activated B-cclls express high-affinity II,-2R of ahout 30~{,

the density found on T-cells. IL-2 enhances proliferation and antibody secretion by

nonnal B-cells at concenttations of two to threef()ld higher than that required to obtain

T-cell response. It also influences the heavy-chain dass S\vitch~ biasing B-cells

towards expression of lgG2 antibodies ( ( )ppenheirn & Ruscetti. 1997).

19

Hurnan n1onocytes and tnacrophages express low levels of IL-2R J3. This is a

low affinity receptor that continuously but inducibly expresses high affinity receptors

containing all three chains on exposure to I L-2, I FNy or other activating agents.

Continued exposure of an activated macrophage to a higher concentration of IL-2 '

enhances its 1nicrocidal and cytotoxic activities, protnotes hydrogen peroxide

production, TN Fa., I L-6 and activation of neutrophils ((>ppenheitn & Ruscetti, 1997~

Benjarnini eta/., 1996 ).

High-dose of IL-2 has been tested as an itnn1unosti1nulatory agent in the

treattnent of a variety of cancers. This produced a partial remission in about 20% of

patients with renal carcinoma or metastatic 1nelano1na (Oppenhei1n & Ruscetti, 1997;

Benjamini eta!., 1996 ).

2.1.2.4.2 IN.fEU.LEtJKIN 4 (IL-4)

IL-4 has a n1olecular weight of 15 000 to 20 000 D. It is a glycoprotein secreted by

activated CD4 T cells of the Tn2 subset and by tnast cells. It was initially identified as

a helper factor forB-cell proliferation and \vas kno\vn as B-cell growth factor-f. IL-4

was also previously known as B-cell stin1ulatory factor-1 hecause of its ability to

induce class 11 MIIC expression on resting B-cells (Clppenheitn & Ruscetti~ 1 997).

1 L-4 ts a tllaJor regulator of the heavy-chain l'lass switch. It promotes

switching to lgG4 and lgE. IL-4 can induce the expression of low affinity Fcc

receptors (C)ppenheim & Ruscetti, 1997).

20

IL-4 also protnotes the induction ofT112 cell that controls the proliferation and

activities of eosinophils and n1ast cells. In contrast, IL-4 suppresses the induction of

Tn I function, which controls rnany facets of cellular i1n1nunity. Besides that., IL-4 also

protnotes cytotoxic T-cell activity, enhances IL-3 rnediated rnast cells growth and acts

synergistically \vith colony stin1ulating factors (CSFs) to enhance the growth of

various hetnatopoietic cells. It also induces vascular cell adhesion n1olecule 1

(VCAM-1) on endothelial cells (CJppenheim & Ruscetti., 1997).

I L-4 produces rnultiple effects on rnacrophages. It activates tnacrophage

cytocidal functions and increases rnacrophages class I MIIC proteins. It also

suppresses the synthesis of proinflatntnatory cytokincs such as IL-l, IL-6., IL-8 and

TNFa that has been produced by activated tnonocytes ((Jppenhcitn & Ruscetti, 1997).

The IL-2 and IL-4 have various effects on inununc function especially on T-cclls and

B-cells respectively (Figure 2. I).

Both innate and acquired ianrnune systems are related and supplcrnent each

other, this relationship is shown in Figure 2.2.

, .. , •: I· ..

t'•,: ;'·;' :I!•' ,,l"tl.•'. 111

I'~ I , : . • I ' I: . , , ' .. '

: .. ,., ... ,I

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',It

·~~~. . \ I (' f>ll•' I'

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r., ,, 1.111• I 't.tf•··f

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:i

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I tr'll''':·

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21

1:. . .......

.. ,, l ~ !

',. 'i , ~ . ' ' ..

I \' .'1:

fl.:. . I I I ~

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I li I i I d

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l;igure 2.1: The nutnerous functions of cytokines in in1tnune system (Shephard et al . .,

1994)

PIIYSICAL

SKIN~

MUCCHJS MEMBI~ANES

INNATE IMMUNITY

PrviN'S~

fV1()N()CYTES~

MACRC>PJ lAG ES, t~(>SINf)PIIII,S,

NKCELLS

22

CIIEMICALS

pi I, I .I PI DS,

ENZYMES

ANTIBODIES

CYTOKINES I LYMPII()KINES cv·t ()K lNES

4 B-CELLS

\ T-CELLS L...f ·r"----.J

AC<JUIRED IMMUNITY

Jiigu.-e 2.2: The interrelationship behveen innate and acquired in1n1unity (Bcnjatnini

el a/., 1996)

23

2.2 PHYSICAL ACTIVITY

Physical activity. exerctse and physical fitness are often used interchangeably

(LaPorte eta/.~ 1985 ). Physical activity is any bodily tnovetnent that results in energy

expenditure above basal rate. It is an inclusive term that includes both static and

dynatnic skeletal contraction as well as aerobic and anaerobic tnetaholistn (lloffn1an­

Goetz~ 1998). Physical activity is liequently tneasured in populations as occupational,

household, leisure tin1e~ recreational and activities of daily living.

Exercise on the other hand, is a subset of physical activity and is defined as

planned. structured., repe1itive activities that itnprove or tnaintain the cotnponents of

physical fatness (Caspersen el al.~ 1985 ). Exercise is usually tneasured in clinical and

experimental setting along the ditncnsions of intensity and duration using tneasures of

tnaxitnal oxygen uptake ( V<>2 n1ax ) .. heart rate and titHe to exhaustion. ()n the other

hand~ physical fitness is conceptualised as the ability to carry out daily task~ including

exercise with vigor., alertness and without undue fatigue (Robbins el a/., 1999).

Physical fitness. which rellects interactions behveen the enviromnent (exercise

training) and genetic capacity~ is ullen tncasured hy cardiorespiratory endurance.

changes in body cornposition. skeletal rnuscle strength. po\ver., speed. flexibility.,

agility. balance and reaction tirne ( J lofriuan-Ooctz. 2000).

The goals of an exercise is to itnprove oxygen delivery and 1netabolic process.,

build strength and endurance., decrease body fat and itnprove n1ovetnent in joints and

1nusc1es. All of these ben~ fits are essential f(n health

24

Exercise should not be used or applied to a ~pecific group of people, and

should be used as a preventive rather than corrective tool. The Atnerican Heart

Association recon1n1ends that individuals engage in 30 tninute or longer workouts at

least three or four tirnes per week. Exercising tnorc than live titnes a week fbr 20 to

24 rninutes each session tnay be closer to optin1un1.

2.2.1 ri'\'JlJ~S ()If Pll YSI( :ALA< ~TIVIT\'

There are a few types of exercise or physical activities that can be applied to obtain

different benefits. This can he divided into three general categories, \vhich are

aerobic., strength and nexibility exercises. It is also recotntnended that a \Veil balance

exercise tnust contain all these three categ.or ies.

Jogging. swtnHntng. cycling. stair clinthing and acrohic dancing arc a fe\v

examples of aerobic exercise. /\crobic exercises build endurance and keep the heart

putnping at a steady but elevated rate l(lr a longer period. < >n the other hand. ftn a

physical activity pyrmnid ( P APt the desired effect is achieved if the aerobic exercise

is done {(lr about25 to 30 tninutes, three to six titnes per v.;eek (Sin1on el a/., 1999).

Strength or resistance training is n1orc on muscle strength. With reference to

PAP, strength training is reconunendcd two or three ti1nes per vveck., one to three set

with eight to twelve repetitions per set. The Arncrit:an l 'ollcgc of Sports Medicine has

recolnnlendcd at least two tin1es per week of strength training. Precautions need to be

taken if 50111e one has cardiovascular disease and arc not advised to do isornetric

training ( Rohhins eta/.. llJ<.JlJ: Sitnon <'lol. 1994 J