The document summarizes the structure and function of the immune system. It describes the cells involved including lymphocytes, macrophages, dendritic cells, granulocytes, and plasma cells. It discusses the development and maturation of lymphocytes in primary and secondary lymphoid organs like the bone marrow, thymus, and lymph nodes. It also describes the activation of T cells and B cells, antigen presentation, and the roles of cytokines in immune responses.

1. STRUCTURE & FUNCTION IMMUNE SYSTEM

2. WHAT IS THIS ? Lymphoreticular system; Complex organization of cells with different morphology and distributed in all organs and tissues of the body and responsible for immunity.

3. 1.Reticuloendothelial component . a) Phagocytic cells. b) Plasma cells. 2.Lymphoid component. a) Lymphocytes (T & B). b) Plasma cells. Non specific Immune response Specific Immune response

4. ORIGIN and ORGANIZATION

5. Myeloblasts Monoblasts Megakaryoblast Proerythroblast Lymphoblasts

7. Lymphopoiesis in central & Peripheral lymphoid organs and mix together constantly to maintain Lymphocyte traffic . Mucosa associated lymphoid tissue

12. Acts as Filters or traps for antigens, become inflamed or enlarged in various conditions distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Garrisons of B, T, and other immune cells dendritic cells, macrophages Lymph node is a small ball-shaped organ of the immune system ,

13. Naive lymphocytes (cells,not yet encountered an antigen) enter the node from the bloodstream, through specialized capillary venules, known as high endothelial venules. After the lymphocytes specialize they will exit the lymph node through the efferent lymphatic vessel with the rest of the lymph. Clinical significance of lymphnode

14. While most of the gut viscera are endodermally the spleen is derived from mesenchymal tissue. The spleen is purple and gray. The spleen is unique in respect to its development within the gut.

20. Distributed as: 1).Diffuse collections. 2).Specialized aggregations Lingual, Palatine, Pharyngeal tonsils. Payer's patches.

21. T cell maturation T - cell precursors Migrate in to thymus Thymic epithelial cells. ( Attains self tolerance , Capacity to recognize Ag- MHC complex ) Synthesis CD3 & acquire new surface Ag ( Thy ag.) Pre T – cells With T- cells receptor ( T C R) Becomes Antigen recognition unit ( I C C ) . (TCR & CD3, Thy proteins)

24. Functional cell

28. Ag + MHC protein on APC TCR on T-cell Production of IL-1 from macrophages. B7 protein on APC + CD28 on helper T-cell Production of IL-2 from T4 - cells. IL-2 is responsible for regulatory,effector and memory functions of t4 cells T-cell activation Responsible for regulatory , effector and memory functions of T-cells. CTLA-4 (Cytotoxic T-lymphocyte antigen-4 ) protein appears on T-cell surface and binds to B7 by displacing CD28 , results in inhibition of IL-2 production. T-cell homeostasis Mutant T-cells which lack CTLA-4 & responsible for autoimmune disease.

29. B – cell maturation Pro – B cell ( From Lymphoid progenitor) Pre – B cell Mature B – Cell (Virgin B-cell) Migrate to peripheral lymphoid tissue Transformed into PLASMA CELL Contact with Antigen Rearrangement of DNA . Express receptors for IgM, IgG, IgA, IgE & for hormones. . Self tolerance .

31. T – Cell B – Cell 1). Location : Thoracic duct Spleen Thymus. 55 – 60% 96% Production, maturation: BM, Thymus B M 2). Thy antigen + - 3). CD3 receptor + - 4). Surface Ig - + 5). S RBC rosette + - 6). E A C rosette - + 7). Blast transformation with anti – CD3 + - anti – Ig - + Endotoxin - +

35. CENTRAL ROLE OF MACROPHAGE IL-1, IL-8 & TNF IL-1

37. Granulocytes (Microphages) Neutrophil: Phagocytic role in acute inflammation Eosinophil: Phagocytic & motile. Parasite killing with hydrolytic enzymes. Basophil: Blood and tissues(Mast cells) Not phagocytic. Receptors for Fc portion of Ig E .

40. 1.MHC class I molecules Fibroblasts, Hepatocytes Lymphocytes, Neuron 2.MHC class II molecules Stromal cells in BM Dendritic cells,Macrophages

43. Further proceed to understand the basis of immune response