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Function - maturation - differentiation

LYMPHOID ORGNS. Function - maturation - differentiation - proliferation Primary ( central ) L.O. T and B startto express Ag - s pecific receptors Secondary (peripheral) L.O. L y proliferation and differentiation after

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Function - maturation - differentiation

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  1. LYMPHOID ORGNS Function-maturation - differentiation - proliferation Primary(central) L.O. T and B startto express Ag - specificreceptors Secondary (peripheral) L.O. Lyproliferation and differentiation after interaction with Ag

  2. Primary(central) L.O. 1) Thymus 2)Bone marrow

  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 proliferation 2)Differentiation 3)Selection

  4. 1) Migration and proliferation Thymocytes react with epithelial cells (cortex), dendritic cells and Mph (medulla) 2)Differentiation 1) step - 3 negat. thymocytes (CD3-,CD4-,CD8-) markers CD44+,CD25+,CD117+ TCR genes not rearranged 2) step- differentiation - TCR  TCR γ markers CD44-, CD25+, CD117+ 3) thymocytes TCR γ   T Ly (CD3+, CD4-, CD8-) 5% of matured T cells thymocytes TCR   Th (CD3+, CD4+, CD8-) Tc (CD3+, CD4-, CD8+)

  5. THYMUS 2 POSITIVE SELECTION Only thymocyteswith affinity to „self“-MHC + Ag survive AIM: Elimination of nonfunctional T cells MHC + epitop-AgTCR/CD3

  6. THYMUS 3 NEGATIVE SELECTION Thymocytes with high affinity to MHC + selfAg are eliminated - clonal deletion or inactivated – clonalanergy AIM:Elimination of AUTOREACTIVE T cells

  7. Secondary lymphoid organs Functions 1.Trapping and concntration of Ag 2.Production of Ab and Ag specific T cells Secondary lymphoid organs: 1.Spleen - blood born microbs and Ag 2.Lymph nodes - lymphatic pathway > skin, mucosa 3. Mucosa associated lymphatic tissue (MALT) – lining of mucosa surface Ag invading mucosa

  8. SPLEEN Function- Ab synthesis and releasing to circulation - hemokaterhesis / Tra Er ( Structure: red pulp white pulp

  9. SLEZINA Red pulp plazma cells, Ma, Er, Tr,PMNL andLy. White pulp - (PeriArteriolarLymphoidSheath- PALS). T cells round central arteria B cells in primary folicules( non stimulated) secondary folicules(Ag stimulated) germinal centre / memory cells B Ly represent 50%spleen cells, 30-40%- T Ly.

  10. Lymph node (LN) Structure - cortx - medulla Cortex Primary folicules–non activated B cells Secondary 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 - Mph Interfolicular space and in paracortex– T cells (mainly Th) Medulla Ly, high number of Mph anddendritic cells

  11. Lymph node (LN) Ag enters LN and trapped by Mph anddendriticcells Degradation of Ag . Fragments (epitopes) are expressed on the surface of APC cells together with MHC molecules Activation of T cells The 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-associatedlymphoidtissues • - (BALT) bronchus-associatedlymphoidtissue • (GUALT) genitourinary-associatedlymphoidtissue • Exmples of MALT: tonsiles, appendix, Peyer`s patches, etc. …

  13. Mucosa associated lymphatic tissue - MALT Structure of MALT 1.Organized MALT (o-MALT) – immune cells in epithelial layer of mucosa and under epithelium Induction of immune reaction 2. DiffuseMALT (d-MALT) – various types of lymphoid cells (B andT Ly, Ma, Ne, Eo, Ma)in laminapropria Effector phase of immune reactions

  14. OrganizedMALT (o- MALT) Peyer`s patches : 1. Lymphoid folicules(>100) central part - B Ly, FDC, DC, Ma peripheral part - T Ly 2. Epithelium - „M“ cells – transport of Ag - intra epithelia T Ly – 80% belong to CD8+ (regulatory function)

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