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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]
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.
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
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
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