1. Lymphocytes and Lymphoid Tissues

2. Basic Pathway Figure 2-3

3. Lymphocytes and Lymphoid Tissues Primary lymphoid tissues ( thymus and bone marrow), Secondary lymphoid tissues (lymph nodes, Peyer’s patches, and spleen) Tertiary lymphoid tissues (skin and mucosal lamina propria)

4. Components of the Immune System I. Bone Marrow - Hematopoietic Stem Cells Myeloid progenitor –neutrophils-macrophage –basophils- mast cells –eosinophils Common lymphoid progenitor –T-lymphocytes –B-lymphocytes

6. Hematopoiesis Hematopoiesis is driven by cytokines:  stem cell factor;  IL-3;  GM-CSF; G-CSF; M-CSF;  IL-7  IL-11

7. Hematopoiesis Erythrocyte-stimulated by EPO (Amgen) EPO = erythropoietin Megakaryocyte/Platelets-stimulated by IL-11 Granulocyte/Monocyte-stimulated by GM-CSF, G-CSF, and M-CSF Lymphocyte -stimulated by IL-7

8. IL-7 Cytokines & growth factors

9. Lymphoid System

10. MALT = mucosal associated lymphoid tissue

11. Lymphocyte Maturation Stem Cell Naïve or virgin lymphocytes migrate to secondary lymphoid organs (short lived) Activation Memory-Effector cells Key Concept

12. Thymus

13. T-Lymphocyte Maturation

14. Thymus thymus  The thymus is an organ strictly dedicated to the selection and differentiation of T lymphocytes.  The T cell precursor cells originate in the bone marrow and then go through a series of developmental steps resulting in the production of a population of mature, antigen-sensitive T-cells.

15. Thymus  The thymus is made up of a cortex and a medulla.  The cortex consists of densely packed immature thymocytes, macrophages, and dendritic cells supported by a thymus stroma largely made up of epithelial cells.  The medulla contains mainly mature thymocytes and macrophages (and a stroma), and the cells are much less dense.

16. Thymus Cortex Medulla

17. Neonatal Thymus

18. Younger Thymus Cortex

19. Younger Thymus Medulla Hassall’s corpuscles are tightly packed epithelial cells from degenerating cells.

20. Adult Thymus atrophies at puberty

21. Clonal Selection-Thymus Each lymphocyte bears a single antigen specificityEach lymphocyte bears a single antigen specificity The a high affinity interaction between the antigen and the T-cell leads to lymphocyte activation.The a high affinity interaction between the antigen and the T-cell leads to lymphocyte activation. Effector cells derived from the activated lymphocyte will bear identical receptors as the parent cell.Effector cells derived from the activated lymphocyte will bear identical receptors as the parent cell. Lymphocyte bearing binding receptors for self-antigens are normally deletedLymphocyte bearing binding receptors for self-antigens are normally deleted.

22. Thymic processing of T-cells

23. Thymic processing of T-cells See notes

24. T-Lymphocytes T-cells –Cellular mediated immunity –Antigen-presentation –Major histocompatibility Complex (MHC) –T-cell Subsets –CD4 (Th1 and Th2) –CD8

25. B-lymphocytes

26. B-Lymphocytes

30. B-Cells - Humoral Immunity B-cell lineage synthesize immunoglobulins virgin Memory Plasma

31. B-Cells - Humoral Immunity Secretion of certain lymphokines –IL-6IgM –IL-6, 4,11IgG –IL-6, 2,5, TGF-  IgA –IL-6, 4IgE Present Antigen to T-cells

32. T-Lymphocytes T-cytotoxic B-cell T-helper APC

33. Lymphocyte Circulation Thoracic Duct

34. Figure 2-1

36. Lymph Node

39. Spleen

40. Complete Pathway KNOW

42. Question 1._____After birth, human B- lymphocyte differentiation takes place in the A. Bone marrow B. Liver C. Gut-associated lymphoid tissue D. Spleen germinal center E. Peyer's patches

43. Question 2._____ The characteristic of the innate immune response is: A. Has memory B. Occurs in minutes to hours C. Takes about 5 days to be effective D. Requires antigen presentation by antigen presenting cells E. Involves the formation of immunoglobulins

44. Question 3._____ The acute-phase (formation of acute phase proteins) response: A. Is stimulated by interleukin-1 , interleukin-6, tumor necrosis factor- , interferon-  B. Is a recent marker of coronary heart disease C. Facilitates the phagocytosis of bacteria D. Is an immunological marker of chronic inflammatory disease E. All of the above

45. Question 4._____Chemotaxis means: A. Phagocytosis of bacteria B. Clonal elimination of B-cells C. Induction of migration of an immune cell D. Adhesion of immune cells to the vascular endothelial cells E. Isotype switch from IgM to IgE

46. Question 5._____ Interferons were first characterized by their: A. Enhancement of B cell proliferation B. Antiviral activities C. Cytotoxicity of transformed cells D. Activation factor for eosinophils E. Stimulation of growth of precursors of all the hemopoietic lineage

47. Question 6.____A plasma cell secretes: A. Antibody of identical specificity to that on the surface of the parent B- cell. B. Antibody of two antigen specificities. C. The antigen it recognizes. D. Antibodies that recognize numerous antigens E. Lysozyme.

48. Question 7._____ Secondary lymphoid tissues include: A. Bone marrow and thymus B. Skin, mucosal surfaces C. Neutrophils and eosinophils D. Complement E. Thymus, lymph nodes, spleen, MALT, and BALT tissues

49. Question 8.____CD8 is a marker of: A. B-cells B. Helper T-cells C. Cytotoxic T-cells D. An activated macrophage E. A polymorph precursor

50. Question 9._____Specific antibodies are readily detectable in serum following primary contact with antigen after: A. After 10 minutes. B. Within 1 hour. C. By 5—7 days. D. After 3—5 weeks. E. Only detectable after a second contact with antigen.

51. Question 10._____Which of the following is a well-known effect of interleukin-8? A. Attraction and activation of neutrophils B. Induction of B-cell proliferation C. Induction of the switch from IgM to IgG synthesis D. Induction of B-cell differentiation E. Suppression of interleukin release by helper T cells

52. Monday’s class There will be no class due to the MLK holiday.