2-Resistance and Acquired Immunity 3

8/8/2019 2-Resistance and Acquired Immunity 3

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Resistance and ImmunityResistance and Immunity


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ImmunityImmunity signifies all those properties of the host thatsignifies all those properties of the host that

confer resistance to a specific infectious agent.confer resistance to a specific infectious agent.

ImmunityImmunity

Natural Acquired or adaptiveNatural Acquired or adaptive

(Innate, nonspecific) (specific)(Innate, nonspecific) (specific)

Active P Active P


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Differences between natural (innate) andDifferences between natural (innate) and

acquired (adaptive) immunityacquired (adaptive) immunity

Innate immunityInnate immunity

11--Present since birth.Present since birth.

22--D

oesnt depend on previousD

oesnt depend on previousexposure to a particularexposure to a particular

pathogen.pathogen.

33--NonNon--specific.specific.

44--Genetically controlled.Genetically controlled.

Adaptive immunityAdaptive immunity

11-- Not present since birth.Not present since birth.

22-- Depends on previousDepends on previousexposure to a particularexposure to a particular

pathogen.pathogen.

33-- Specific.Specific.

44--Genetically controlled andGenetically controlled andinfluenced by hormonesinfluenced by hormones

and cytokines.and cytokines.


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Innate immunityInnate immunity

55-- No immunologicNo immunologic

memory.memory.

66-- Modified by : age,Modified by : age,hormones, nutritionalhormones, nutritional

status.status.

Adaptive immunityAdaptive immunity

55-- Involves theInvolves the

development ofdevelopment of

memory cells.memory cells.

66-- Formed of 2 arms:Formed of 2 arms:humoral and cellhumoral and cell--

mediated.mediated.


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Determinants of Innate ImmunityDeterminants of Innate Immunity

11-- Species and strain.Species and strain.

22-- Individual differences.Individual differences.

33-- Age and sex.Age and sex.44-- Hormonal factors.Hormonal factors.

55-- Nutritional factors.Nutritional factors.

66-- Racial immunity.Racial immunity.


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Mechanisms of Innate ImmunityMechanisms of Innate Immunity

11-- Mechanical barriers and surface secretions:Mechanical barriers and surface secretions:intact skin, mucous membrane.intact skin, mucous membrane.

22-- Commensal bacteria:Commensal bacteria:salivary streptococci, vaginalsalivary streptococci, vaginal

lactobacilli.lactobacilli.

33-- Bactericidal substances:Bactericidal substances: present normally in bodypresent normally in bodyfluids and include:fluids and include:

a)a)--Lysozyme b)Lysozyme b)--GIT secretions c)GIT secretions c)--Lactenin d)Lactenin d)--Oleic acidOleic acide)e)--Spermine and spermidineSpermine and spermidine

f)f)--Bactericidal activity of the blood due to:Bactericidal activity of the blood due to:

1. Complement 2. Natural Abs1. Complement 2. Natural Abs

3. Properdin 4.Phagocytes3. Properdin 4.Phagocytes


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44-- Phagocytosis:Phagocytosis: enhanced by opsonization of particles byenhanced by opsonization of particles by

opsonins as: Abs, C3 or C reactive protein (CRP).opsonins as: Abs, C3 or C reactive protein (CRP).

55-- Inflammatory response:Inflammatory response: limits the spread oflimits the spread oforganisms.organisms.

66-- Fever:Fever: induced by ILinduced by IL--1, IL1, IL--6, TNF alpha.6, TNF alpha.

77-- Natural killer (NK) cells :Natural killer (NK) cells : nonnon--specifically recognizespecifically recognizeand attack tumour cells and virusand attack tumour cells and virus--infected cells .infected cells .

88-- TollToll--like receptors (TLRs).like receptors (TLRs).


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OpsonizationOpsonization


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ADCC by NK CellsADCC by NK Cells


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Destruction of VirusDestruction of Virus--Infected Cells by NK Cells throughInfected Cells by NK Cells through

AntibodyAntibody--Dependent Cellular Cytotoxicity (ADCC)Dependent Cellular Cytotoxicity (ADCC)


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TollToll--like receptorslike receptors

They are glycoproteins.They are glycoproteins.

They are found on the surface of most bodyThey are found on the surface of most body

immune cells.immune cells.They recognize and bind to pathogenThey recognize and bind to pathogen

associated molecular patterns (PAMPs).associated molecular patterns (PAMPs).


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PAMPs:PAMPs:

These are highly conserved structures presentThese are highly conserved structures present

in different organisms.in different organisms.

They include:They include:11-- Bacterial moleculesBacterial molecules as peptidoglycan,as peptidoglycan,

teichoic acid and LPS.teichoic acid and LPS.

22-- Fungal moleculesFungal molecules as zymosan and mannan.as zymosan and mannan.33-- Viral moleculesViral molecules as viral nucleic acids andas viral nucleic acids and

proteins.proteins.


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Binding of TLRs to PAMPs ofBinding of TLRs to PAMPs ofbacteria andbacteria and

fungifungi triggers synthesis of cytokines bytriggers synthesis of cytokines byimmune cells (e.g. ILimmune cells (e.g. IL--2, IL2, IL--8 and TNF8 and TNF--

alpha) which triggers immune defences asalpha) which triggers immune defences as

inflammation, fever and phagocytosis.inflammation, fever and phagocytosis.

Binding of TLRs toBinding of TLRs toviral componentsviral components

triggers synthesis of interferon and blockstriggers synthesis of interferon and blocksviral replication.viral replication.


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Acquired ( Adaptive) ImmunityAcquired ( Adaptive) Immunity

ActiveActive PassivePassiveNaturalNatural ArtificialArtificial NaturalNatural ArtificialArtificial

(Infection)(Infection)

(Immunizing agents)(Immunizing agents)

Clinical SubclinicalClinical Subclinical (Placental transfer,(Placental transfer,

colostrum)colostrum)

(administration of immune sera)(administration of immune sera)


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Acquired (Acquired (AdaptiveAdaptive) Immunity) Immunity

Acquired Active ImmunityAcquired Active Immunity

11-- The host actively producesThe host actively produces

Abs.Abs.

22-- Immunity is of delayedImmunity is of delayed

onset.onset.

33-- Abs last longer.Abs last longer.

Acquired Passive ImmunityAcquired Passive Immunity

11-- The host receives preformedThe host receives preformed

Abs.Abs.

22-- It gives immediate protection.It gives immediate protection.

33-- Immunity is temporary.Immunity is temporary.


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ImmunizingImmunizing AgentsAgents

Bacterial Vaccines:Bacterial Vaccines:a)a) Heat killed:Heat killed:T.A.B for enteric fever.T.A.B for enteric fever.

b)b) Live attenuated:Live attenuated: B.C.G. for tuberculosis.B.C.G. for tuberculosis.

c)c) Bacterial components:Bacterial components: CapsularCapsularpolysaccharides of meningococci and H.polysaccharides of meningococci and H.

influenzae for meningitis.influenzae for meningitis.

d)d) Bacterial products:Bacterial products:Toxoids ofToxoids ofDiphtheria bacilli for diphtheria, and Cl.Diphtheria bacilli for diphtheria, and Cl.

tetani for tetanus.tetani for tetanus.


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ImmunizingImmunizing AgentsAgents

Viral Vaccines:Viral Vaccines:

a) Inactivated:a) Inactivated: Salk vaccine for poliomyelitisSalk vaccine for poliomyelitis..

b) Attenuated:b) Attenuated: Sabin vaccine for poliomyelitis.Sabin vaccine for poliomyelitis.

c) Recombinant peptide:c) Recombinant peptide: Hepatitis B vaccine.Hepatitis B vaccine.


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Adjuvants:Adjuvants:

-- nonnon--specifically enhance the immunespecifically enhance the immune

response to an Ag.response to an Ag.

-- usually required with nonusually required with non--living vaccines.living vaccines.

-- e.g. aluminium hydroxide used withe.g. aluminium hydroxide used with

diphtheria and tetanus toxoids.diphtheria and tetanus toxoids.

2-Resistance and Acquired Immunity 3

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