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Cells of the Immune System (Hematopoiesis (in bone marrow) (1) lymphoid…
Cells of the Immune System
Cells of the Innate IS
Innate Lymphoid Cells
e.g. Natural Killer Cells
kill infected and stressed cells
Missing self hypothesis
produces IFN-G
produce different cytokines to regulate IR (eg IFN-G)
Monocytes
a) Dendritic Cell
AG presentation (take up micorbes & process AG to show to T)
in every organ
2 different origins (fetal and adult in b. m.)
b) Macrophages
2 different origins
fetal hematopoiesis (migrate in target organs & differentiate in organ adapted cells)
adult H. in bone marrow (--> Monocytes in blood; if infection --> go to infected tissue & activated and differentiate into Inlflammatory M. --> further activation by IFN-G and microbe products)
Effector Functions upon activation:
a) phagocytosis via Ph. Receptor
b) expressing enzymes that create inorganic radicals (Phagocyte-Oxidase; inducible Nitric Oxide Synthase)
c) prodcution of cytokines --> inflammation and regulation of IR
d) AG presentation
Activation: IFN-G; PAMPs that bind to Toll-like Receptor
Macrophage Polarization
M1: proinflammatory (acti. via INF-G)
M2: stops inflammation (act. via spec. Cytokines)
Monocytes in blood; Macrophages in organs
Neutrophils
important early component of inflammatory response
short lived (t1/2 = 9h)
phagocyte --> against extrac. microbes
Cells of the Adaptive IS
T Lymphocytes
Th
activate macrophages via IFN-Gamma
lead to inflammation
activation of T and B
Tct
kill infected cells
Treg
suppress other lymphocytes --> imm. tolerance
recognize AG presented with MHC
B Lymphocytes
Plasma Cells: produce ABs
recognize native AG
need to be activated bei Th
Hematopoiesis (in bone marrow)
pluripotent hematopietic stem cell
--> mulitpotent progenitor
--> commited precursor
1) lymphoid lineage
--> common lymphoid precursor
--> PRO T/B cell
--> PRE T/B cell
--> final naive T/B cell (go to secondary lymphoid organ & RECIRCULATION)
T in Thymus / B in b. m.
--> in 2. l. o.: contact with AG --> diff. in effector cells --> go to infected tissue
2) myoloid lineage (Monocytes (=Macrophages+DC), Neutrophils, Basophils, Eosinophils)
is driven by Hematopoietins (cytokines that drive H.)
Lymphoid Tissue
Generative Organs
Thymus
Bone Marrow
Secondary Lymphoid Organs
Lymph Nodes
DC carry AG here; or is flushed in
are concentrated strategically
Draining Lymph node (=lymph node to which the AG of a particular region is carried)
Thoracic Duct (= all lymph. vessels end in it; is connected to blood steam)
Spleen
filters AG out of blood
RECIRCULATION of naive T/B bt. those (so that complete imm. repertoire)
Regulation of Movement (Integrins, Selectin-Ligand and Chemokines)
here T/B come in contact with AG
Residence of Memory T/B
Leukocyte Migration
infection --> change in migration pattern
Neutorphils & Monocytes: site of infection --> inflammation
naive B/T: migrate into 2. l. o.
effector B/T: site of infection --> cell-mediated immunity
how?:
change of gene expression:
Leukocytes: different Homing Receptors (= Integrin) and Chemokine Receptors and Selectins
Endothelial Cells: diff. Tissue Adhesion Molecules
Leukocyte adhesion to endothelia:
Selectin Ligand + Selectin
Chemokine Receptor + Chemokine (--> Integrin activation to extended structure)
Integrin + Adhesion Molecule