Adaptive Immunity :- Lymphocytes.pptx

Adaptive Immunity :- Lymphocytes.pptx

1. A daptive immunity-lymphocyte DR. vaidehi patel

2. SKIN ASSOCIATED LYMPHOID TISSUE Circulating immune cells that continually traffic in a directed manner b/w skin, draining lymph node, and the circulation, thus providing optimal immunosurveillance. Leukocyte clustering structure of DCs and macrophages for efficient within skin antigen presentation

3. It basically consists of macrophages and mast cells that appear transiently around the postcapillary venules in response to immunologic stimuli These macrophages cause neutrophil extravasation by releasing CXCL1 and CXCL2 External insult causes Il-1 production and M2 macrophage activation, which releases CXCL2 and LTB4, that recruit dermal DCs to leukocyte cluster. This enables in situ APCs by these cell clusters to naive T cells

4. T LYMPHOCYTES Naive t cells express CD45 RA and CCR7 On activation by MHC presentation of APC in nodes convert to effector memory T cells, that secrete IL-2,IFN-gamma and TNF Normal epidermis harbors CD8+ TRM in suprabasal layers,in close proximity to langerhans cell, alongwith CD4+ cells Normal dermis harbors CD4+ TRM cells beneath DEJ around post-capillary venules and periappendageal region

5. T-cell mediated pathogen specific immune response : Phase 1 - tissue resident memory T cell Phase 2 - non specific recruitment of circulating TRM Phase 3 - antigen specific DC migration to regional lymph nodes and pathogen specific effector TRM homing to skin

6. Th1 immunity : Against i ntracellular microbes - M.tb, leishmania, toxoplasma,other bacteria, protozoa and viruses Activate macrophages Secrete IFN-gamma, TNF, LT-alpha Antiviral - enhance cytolytic activity against infected cells

7. Th2 immunity Protects against helminths, ectoparasites ( including ticks and mosquitoes), environmental irritants and venom Secrete IL-4 and 13 : essential for isotype switching of B-cells Secrete IL-5 : differentiation, activation of eosinophils

8. Th17 immunity Against extracellular bacteria and fungi : klebsiella pneumoniae, staph aureus, and candida albicans Secrete : IL-17 - neutrophil recruitment, PGE2 mediated vasodilation, IL-22 - epithelial cell homeostasis, antimicrobial defense, wound healing ( IL-17 receptor deficiency - linked to candida species infection)

9. NKT cells: Characteristics of both Recognize bacterial glycolipids and role in antimicrobial immunity Important role in allergic contact dermatitis Hair follicles are a site of immune privilege : MHC-I downregulation in follicular keratinocytes Produce IL-10 and TGF-B Unique ECM in perifollicular zone Fas ligands : to detect autoreactive CD8+ cells

10. B -LYMPHOCYTES ROLE : protection of extracellular spaces through generation of effector memory B- cells and B cell produced antibodies, leading to neutralization and opsonization of pathogen and providing immunological memory Antibody independent roles: APC Cytokine production

11. After APC activation of B- cells in secondary lymphoid organs, the migration of B-cell from peripheral circulation into tissue sites is governed by interaction b/w selectins, chemokine receptors and integrins with their cognate ligands CCR6 (B-cell) - CCL20 in the skin endothelium drive the skin resident CLA+ B-cells into skin in the steady state. B-cells occur infrequently in normal skin under homeostatic conditions.

12. Dermal B-cell infiltrates - chronic inflammatory conditions: cutaneous leishmaniasis, diffuse systemic sclerosis, and atopic dermatitis Autoimmune bullous disorders are characterized by presence of circulating autoantibodies against structural proteins of epidermis or dermo-epidermal junction. ( mature CD20+ Bcell depletion by rituximab is emerging first line therapy )

13. INNATE Vs ADAPTIVE IMMUNITY

14. THANK YOU