1. Human immune system CELLS COOPERATION IN IMMUNE RESPONSE

2. PRIMARY OR CENTRAL LYMPHOID ORGANS are responsible for synthesis and maturation of immunocompetant cells. These include the bone marrow and the thymus. PERIPHERAL OR SECONDARY LYMPHOID ORGANS are sites where the lymphocytes localise, recognise foreign antigen and mount response against it. These include the lymph nodes, spleen, tonsils, adenoids, appendix, and clumps of lymphoid tissue in the small intestine known as Peyer's patches. They trap and concentrate foreign substances, and they are the main sites of production of antibodies.

4. White Blood Cells Phagocytes - Neutrophils Macrophages Lymphocytes Cells of the Immune System

6. White blood cells

7. Lymphocyte (could be B cell or T cell!)

8. Lymphocytes Present in lymphoid organs and in blood Groups T-lymphocytes (grow up in thymus) B-lymphocytes (grow up in bone marrow) Each one has receptors for a specific antigen Recognize millions of different antigens! Diversity generated by: rearrangement of antigen receptor genes different joining of the gene segments Gene rearrangement studies

11. Lymphocytes Live in blood, bone marrow, lymphoid tissues Basic function: make antibodies (immunoglobulins) B-cell receptor complex recognizes antigens binds antigen sends signals to T cells Antigens can be free and circulating (don’t have to be bound to MHCs or displayed by other cells to be recognized!) B lymphocytes

12. The B-Cell Receptor

16. Lymphocytes Live in blood, bone marrow, lymphoid tissues Two basic functions: kill stuff help other cells do their jobs T-cell receptor (TCR) complex recognizes antigens binds antigen sends signals to the T cell Antigens must be: displayed by other cells… …AND bound to an MHC receptor T lymphocytes

18. Chapter 21, Immune System18 T Cell Selection in the Thymus Figure 21.7

20. The T-Cell Receptor

21. Antigen-presenting cell T cell

26. Lymphocytes Helper T cells CD4+ (and CD8-) help B cells make antibodies help macrophages eat bugs decreased in patients with AIDS Cytotoxic T cells CD8+ (and CD4-) kill virus-infected cells and tumor cells T lymphocytes

27. CD8+ T cells surrounding tumor cell

28. Lymphocytes Belong to innate immunity arm No highly variable receptors like T and B cells Main job: recognize and kill damaged or infected cells Antigens don’t have to be bound to MHCs or displayed by other cells! Natural Killer Cells

29. Natural killer cell

30. Natural killer cell (top) killing infected cell (bottom)

31. Antigen-presenting cells Main job: catch antigens and display them to lymphocytes Dendritic cells Have fine cytoplasmic projections Present all over body: skin, lymph nodes, organs Capture bug antigens, display to B and T cells Other APCs Macrophages eat bugs and present antigens to T cells, which tell macrophages to kill bugs B cells present antigens to helper T cells, which tell B cells to make antibodies

33. dendritic cells

35. Antigen-presenting cells (APC) activate T helper cells

36. APC presents peptide to Т helper

37. T helper 2 activates B lymphocyte

39. Humoral immune response

42. Cell-mediated immune response

44. Взаємодія клітин в імунній відповіді