ACQUIRED IMMUNITY

ADAPTIVE IMMUNE SYSTEM

1. Adaptive immune system Four characteristics _ diversity -in recognizing structure of antigens Antigenic Specificity – ability to recognize and respond to particular targets . Memory – second exposure to the same organism produces a larger and more rapid response than occurred at the primary exposure . Self/non self recognition

2. TYPES OF IMMUNITY

3. ACTIVE IMMUNITY EXPOSURE TO ANTIGEN IMMUNITY ACHIEVED BY INJECTING ANTIGENS ACTIVATION OF IMMUNE SYSTEM IMMUNE STATE DEVELOPS OVER A PERIOD OF WEEKS IMMUNOLOGICAL MEMORY DEVELOPS PASSIVE IMMUNITY NO EXPOSURE TO ANTIGEN IMMUNITY ACHIEVED BY INJECTING Ab or Ag REACTIVE T CELLS NO IMMUNE SYSTEM ACTIVATION IMMUNITY DEVELOPS IMMEDIATELY NO IMMUNOLOGICAL MEMORY DEVELOPS

4. B lymphocytes Mature within bone marrow B cells receptor is a membrane bound antibody molecules. Can recognize antigen alone Two types- Memory B cell- longer life span -same membrane bound antibody as their parent B cells Plasma cells-secretes antibodies

5. b) Antigen presenting cells They express class ll MHC molecule on their membrane. They are to deliver a single that is necessary for T helper cell activation

6. c) T lymphocytes Formation and maturation Recognizes only antigen bound to cell membrane proteins called major histocompatibility complex (MHC) Two type of MHC molecule- Class l MHC-expressed by all nucleated cells of vertebrates species Class ll MHC- expressed by only antigen presenting cells

7. Helper T lymphocyte Have CD4 glycoproteins on their surface. Interact with MHC class ll molecules Secretes many growth factors, cytokines, interleukin Activate s macrophages, B cells, Tc cells and other cell

8. Activation of T cells: Helper Activated helper T cell Monokines MHC Class II T cell receptor Antigen-presenting cell CD4 protein Antigenic peptide Antigen is processed Resting helper T cell Class II MHC Lymphokines Helper T cell receptor recognizes processed antigen plus Class II MHC Macrophage Processed antigen and Class II MHC are displayed Antigen Helper T cell

9. T cytotoxic cells Also known as killer T cells. Have CD8 glycoprotein Stimulated by cytokines released by T helper cells Recognizes antigen MHC class l molecules complex Differentiates into cytotoxic T lymphocytes No cytokine secretion Exhibits cell killing activity for altered self cells-tumor cells & virus infected cells

10. Antigen receptors Killer cell Infected cell Antigen-presenting cell Antigen-presenting cell CD8 protein Cell membrane MHC Class I MHC Class I Antigenic peptide T cell receptor CD4 protein Cell membrane MHC Class II Antigenic peptide T cell receptor Cell membrane Antigen Antigen-specific receptor Helper T cell B cell

11. Types of immune response

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