Molecular Immunology -Cells and Tissues of the

Immune System

SathiyaRaj Dept. of Oriental Medicinal Materials and ProcessingSchool of Life Science,Kyung Hee University.South korea.

ANATOMY OF THE IMMUNE SYSTEMANATOMY OF THE IMMUNE SYSTEM

The immune system is The immune system is localized in several localized in several parts of the bodyparts of the body immune cells immune cells

develop in the develop in the primary organsprimary organs - - bone marrow and bone marrow and thymus (yellow)thymus (yellow)

immune responses immune responses occur in the occur in the secondary organssecondary organs (blue)(blue)

Our 1Our 1stst Line of Defense... Line of Defense...

The Integumentary System…The Integumentary System…SkinSkinMucous membranesMucous membranesMucousMucous

provides a physical barrier provides a physical barrier preventing microbial access preventing microbial access

The Invaders . . . The Invaders . . .

BacteriaBacteria

VirusesViruses < Click to find out more about Microbes< Click to find out more about Microbes

& Disease > & Disease >

parasites parasites such as fungi, such as fungi, protista, & wormsprotista, & worms

worm trichura.jpg

http://www.hhs.gov/asphep/presentation/images/bacteria.jpg

http://www.sdnhm.org/exhibits/epidemic/teachers/background.html

http://www.skidmore.edu/academics/biology/plant_bio/lab13.FUNGI.html

Other mechanisms of Other mechanisms of Defense...Defense...

Physiological variablesPhysiological variablespH of our environmentpH of our environmenttemperature of our environmenttemperature of our environment

chemical defenseschemical defensesnitric oxide, enzymes, proteins, nitric oxide, enzymes, proteins,

complementcomplement

AND the IMMUNE SYSTEM…AND the IMMUNE SYSTEM…

Immune System : Immune System : 2 branches2 branches

The Innate Immune system =The Innate Immune system =a general response to anything other a general response to anything other

than recognized “self cells”than recognized “self cells”

The Adaptive Immune System =The Adaptive Immune System =a specific counter-assault against a a specific counter-assault against a

“known foreign” invader [previously “known foreign” invader [previously recognized]recognized]

Cells of the Immune Cells of the Immune SystemSystem

The cells of the adaptive system are normally present as circulating cells in the blood and lymph as anatomically defined collections in lymphoid organs, and as scattered cells in virtually all tissues.

Only a small number of lymphocytes specifically recognize and respond to any one antigen.

Adaptive immune responses are initiated in specialized tissues called peripheral lymphoid organs, which efficiently concentrate antigens that are intrduced through the common portals of entry (skin and gastrointestinal and respiratory tracts)

Lymphocytes are the only cells in the body capable of specifically recognizing and distinguishing different antigenic determinants and are therefore responsible for the two defining characteristics of the adaptive immune response, specificity and memory.

Cells of the Immune SystemCells of the Immune System

Source: http://www.biologymad.com/

MenuMenu FFBB

Classes of Lymphocytes

Naive Activated EffectorPhases of

LymphocyteActivation

MenuMenu FFBB

Neutrophil

Eosinophil

Basophil

Granulocytes

What Happens during an What Happens during an infection?infection?

Innate Immunity -Innate Immunity - the troops are called to battle… the troops are called to battle… injury & infectioninjury & infection macrophages slip between cells macrophages slip between cells [extravasation][extravasation]

to arriveto arrive cytokine chemicals attract other “troops” cytokine chemicals attract other “troops”

[chemotaxis][chemotaxis] histamine chemicals dilate blood vessels for histamine chemicals dilate blood vessels for

easier access to injury easier access to injury [vasodilation][vasodilation] < Click on link to view Movie of inflammation >< Click on link to view Movie of inflammation >

http://www.muhealth.org/~pharm204/inflammation.movhttp://www.muhealth.org/~pharm204/inflammation.mov

Principal mechanisms of defense against microbes

Antibodies Phagocytes T cells (CTLs) (may work with antibodies, T cells)

All microbes

All microbes

Intracellular microbes, esp.

viruses

Thymus

Bone MarrowBursa

Peyer's Patches(Ruminants,Pigs)

Primary/Generative

Spleen

Lymph Nodes

Cutaneous

Mucosal

Secondary

Lymphoid Organs

Lymphoid Organs

• Primary (Generative) Lymphoid Organs– maturation site of ly

mphoid cells– bone marrow, bursa

of Fabricius, thymus, Peyer’s Patches in Pigs and Ruminants

• Secondary Lymphoid Organs– efficient at trapping an

d concentrating foreign substances

– site of Ag-driven proliferation and differentiation; e.g. Ab production

– spleen, lymph nodes, diffuse tissues

Anatomy of a lymph node

Naïve lymphocytes circulate between blood and lymphoid tissues; antigen in tissue arrives at draining lymph node via lymph flow and being carried by dendritic cells

Applies to B cells and T cellsFor T cells: costimulatory molecules include B7-1 and B7-2 on dendritic cells

Mechanism for directing the immune response against microbes and not against self, food, etc.

Congenital immunodeficiency diseases are often caused by blocks at different stages of lymphocyte maturation

LYMPHOCYTE DEVELOPMENT

The Immunoglobulin Superfamily(a few examples)

Integrins: Regulated Cell-cell and cell- ECM adhesion

Cytokine receptor families

How can antibodies distinguish “self”cells from

foreign invaders?• Adaptive Immune System - origin

• There are 2 types of lymphocytes:

– 1st Type - T lymphocytes - [ T - Helper cells ] begin in the red bone marrowhttp://www.sirinet.net/~jgjohnso/skeletonorg.html

& migrate to the thymus gland ...

• These Lymphocytes are sorted into 2 types

• Identification tag is a protein called Major Histocompatability Complex [MHC]

Self- IDForeign

B cells differentiate into . . .

– Antibody producing cells [attack mode]

– Memory cells [remembers & future protection]Antigen & T-helper cell

memory

antibodies

Inflammatory reaction

T Cells Maturein Thymus

Stem Cellsof the BoneMarrow

IdentifyAntigens

B Cells Replicate to formPlasma cells

B MemoryCells

Released intoblood, spleen,lymph

Macrophagescarry foreigncells to THelper cells

T Helper cells (Th)produce proteins

SecreteInterleukins

Secretelymphokines

ReleaseAntibodies

StimulatesPhagocytosis

Effector TcCells

Tm MemoryCells

B Cells Maturein Marrow

ReplicateCytotoxic (killer)T (Tc) Cells

Antibody MediatedImmunity

Cell MediatedImmunity

LymphocyteMaturation

Antibody Mediated Immunity

• Animation of Antibody Mediated Immunity

• What kind of cell does the macrophage activate in the humoral immune response?

• What occurs during the effector phase of the humoral response?

http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm

Cell Mediated Immunity:

http://press2.nci.nih.gov/sciencebehind/immune/immune00.htm