Presentation on theme: "LYMPHOID ORGNS Function - maturation - differentiation - proliferation"— Presentation transcript:
1 LYMPHOID ORGNS Function - maturation - differentiation - proliferation Primary (central) L.O.T and B startto expressAg - specific receptorsSecondary (peripheral) L.O.Ly proliferation and differentiation afterinteraction with Ag
3 Thymus 1 Morphology: lobular organ cortex medulla Function: maturation of T cells (only 1 x 106 of 5 x 107 tymocytov mature)Maturation: 3 STEPS:1) Migration and proliferation2) Differentiation3) Selection
4 1) Migration and proliferation Thymocytes react with epithelial cells (cortex), dendritic cells and Mph (medulla)2) Differentiation1) step - 3 negat. thymocytes (CD3-,CD4-,CD8-)markers CD44+,CD25+,CD117+TCR genes not rearranged2) step - differentiation - TCR TCR γmarkers CD44-, CD25+, CD117+3) thymocytes TCR γ T Ly (CD3+, CD4-, CD8-)5% of matured T cellsthymocytes TCR Th (CD3+, CD4+, CD8-)Tc (CD3+, CD4-, CD8+)
5 THYMUS 2 POSITIVE SELECTION Only thymocytes with affinity to „self“-MHC + Ag surviveAIM: Elimination of nonfunctional T cellsMHC + epitop-Ag TCR/CD3
6 THYMUS 3 NEGATIVE SELECTION Thymocytes with high affinity to MHC + self Agare eliminated - clonal deletionor inactivated – clonal anergyAIM: Elimination of AUTOREACTIVE T cells
7 Secondary lymphoid organs Functions1. Trapping and concntration of Ag2. Production of Ab and Ag specific T cellsSecondary lymphoid organs: Spleen - blood born microbs and Ag Lymph nodes - lymphatic pathway > skin, mucosa3. Mucosa associated lymphatic tissue (MALT) – lining of mucosa surfaceAg invading mucosa
8 SPLEEN Function - Ab synthesis and releasing to circulation Function - Ab synthesis and releasing to circulation- hemokaterhesis / Tr a Er(Structure: red pulpwhite pulp
9 Spleen Red pulp White pulp - plasma cells, Ma, Er, Tr, PMNL and Ly. (PeriArteriolar Lymphoid Sheath - PALS).T cells round central arteriaB cells in primary folicules ( non stimulated)secondary folicules (Ag stimulated)germinal centre / memory cellsB Ly represent 50% spleen cells, % - T Ly.
10 Cortex Medulla Structure - cortx - medulla Lymph node (LN)Structure - cortx- medullaCortexPrimary folicules – non activated B cellsSecondary folicules - response to Ag- Activated B cels – differentiation to plasma cells- Th support B cell differentiation- dendritic cells – Ag presentation- FDC - activation of memory cells- MphInterfolicular space and in paracortex – T cells (mainly Th)MedullaLy, high number of Mph and dendritic cells
11 Lymph node (LN) Ag enters LN and trapped by Mph and dendritic cells Degradation of Ag . Fragments (epitopes) are expressed on the surface of APC cells together with MHC moleculesActivation of T cellsThe first mitotic wave in T zones is recorded 1-2 days after contact with Ag prolif. of B Ly, germinal centrers
12 Immune system of mucosa - MALT >50% of lymphoid tissue- (GALT) gut-associated lymphoid tissues- (BALT) bronchus-associated lymphoid tissue(GUALT) genitourinary-associated lymphoid tissueExmples of MALT: tonsiles, appendix, Peyer`s patches, etc. …
13 Mucosa associated lymphatic tissue - MALT Structure of MALT1. Organized MALT (o-MALT) – immune cells inepithelial layer of mucosa and under epitheliumInduction of immune reaction2. Diffuse MALT (d-MALT) – various types of lymphoid cells(B and T Ly, Ma, Ne, Eo, Ma) in lamina propriaEffector phase of immune reactions
14 Organized MALT (o- MALT) Peyer`s patches :1. Lymphoid folicules (> 100)central part - B Ly, FDC, DC, Maperipheral part - T Ly2. Epithelium- „M“ cells – transport of Ag- intra epithelia T Ly – 80% belong to CD8+ (regulatory function)
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