IT’S THE IMMUNE SYSTEM

1. IT’S THE IMMUNE SYSTEM BOGGUSRL@email.uc.edu

2. BEFORE WE BEGIN: • Share this with others. It’s the most amusing thing I have seen in some time: http://www.dvo.com/newsletter/monthly/2004/august/pinkey.wmv Pinkey, pet of the week. Gotta love it.

3. First a request from last time

4. Overview • Where do all cells that constitute the immune system come from? • What percentage of WBCs are monocytes? • What do they become in tissue?

5. Overview • Where do all cells that constitute the immune system come from? • From a self-renewing stem cell in the bone marrow • What percentage of WBCs are monocytes? • 2-8% • What do they become in tissue? • macrophages

6. Lymphocytes • What percentage of WBCs are lymphocytes? • What are the two broad categories of lymphocytes?

7. Lymphocytes • What percentage of WBCs are lymphocytes? • 20-30% • What are the two broad categories of lymphocytes? • T-cells and B-cells

8. B-cells • What do B-cells give rise to? • How can you ID them in H&E, EM?

9. B-cells • What do B-cells give rise to? • Plasma cells • How can you ID them in H&E, EM? • H&E— beer belly and golgi ghost • EM—lots of RER, hypertrophied golgi • Remember they synthesize antibodies • No storage granules b/c ab secreted

10. T-Cells • What are the three categories of T-cells?

11. T-Cells • What are the three categories of T-cells? • Helper T cells • Cytotoxic/killer T cells • Suppressor T cells

12. The Immune System • What is the major responsibility of the immune system? • What initiates the immune response?

13. The Immune System • What is the major responsibility of the immune system? • The discrimination of self from non-self • What initiates the immune response? • Antigen-presenting cells (APCs)

14. What are the two arms of the immune system? • What happens once an immune response is initiated (generally speaking)?

15. What are the two arms of the immune system? • T-cell (cell mediated), B-cell (humoral) • What happens once an immune response is initiated (generally speaking)? • Both arms generate effector cells and memory cells • Effector cells are involved in elimination of “non-self” • Memory cells go to lymph tissue and hibernate

16. T-Cell mediated immunity • What is it synonymous with and an give an example of each

17. T-Cell mediated immunity • Delayed-type Hypersensitivity • think TB test at Holmes – you have to go back to get it read in 2 days to see if there is a rxn…. Or never go back like me • Allograft rejection • Transplant rejection • Contact Sensitivity • Poison ivy • Graft-vs-Host Disease • Bone marrow transplant – the donor attacks the host cells

18. B-cell function • What are the five classes of immunoglobulins and their functions? • IgA—secretory antibody (mucosal immunity) • Secreted by transcytosis, has secretory component • IgD—function unknown • IgE—allergic Ab… think mast cells • IgG—serum antibody – in BLOOD • IgM—first and largest antibody – PENTAMERIC (in groups of 5)

19. Major Histocompatibility Protiens • What cells express Class I MHC? • What do cells of the immune system have?

20. Major Histocompatibility Protiens • What cells express Class I MHC? • All nucleated cells • Class 1 MHC presents antigens that are present INSIDE the cell. Makes sense that all cells express MHC 1 because any cell can be invaded by bacteria What do cells of the immune system have? • Either class II MHC proteins or receptors for Class II MHC proteins • Makes sense because class 2 presents EXTRACELLULAR antigens and only phagocytes can engulf the extracellular bacteria

21. Definitions • Syngenic • Allogenic • Xenogenic

22. Definitions • Syngenic • Genetically identical Allogenic • Genetically dissimilar individuals within the same species (i.e. siblings) • Xenogenic • Genetically dissimilar and from a different species (man and mouse)

23. Generation of Cytotoxic T-cells • What are the stages of generation of cytotoxic T-cells?

24. Generation of Cytotoxic T-cells • What are the stages of generation of cytotoxic T-cells? • ACTIVATION: Precursor CT-cells bind novel hybrid antigen on surface of APC • MATURATION: Cytokines and lymphokines secreted by Th1 drive maturation to Tc • KILLING: Activated Tc cells find infected target cells and deliver perforinapoptosis

25. NOTE • Activation of T cells requires MHC class II • Killing requires MHC class I

26. Activation of B cells • Uncommitted B cells express bound IgM • Encounters foreign epitope • Internalizes and processes antigenAPC • Before transformation to plasma cell it needs lymphokines from Th2 cells.

27. Lab stuff • What constitutes mucosa? • What is the lamina propria

28. Lab stuff • What constitutes mucosa? • Epithelium and lamina propria and sometimes a layer of smooth muscle or elastic fibers • What is the lamina propria • Layer of loose CT under epithelium of mucosal surfaces, where lymph tissue is found between red arrows

29. Diffuse Lymphoid tissue

30. Peyer’s Patches • Have germinal centers • Inner light zone surrounded by dark rim of lymphocytes

31. Palatine Tonsil • You will differentiate it because it has stratified squamous epithelium on one side or just CT on the other! • Note CT septa and crypt (gap in middle of tonsil)!

32. Macrophages • “starry sky” appearance – i don’t see this but whatever

33. Pharygeal tonsil • ANY pseudostratified ciliated columnar epithelium on a tonsil makes it a pharyngeal tonsil

34. What is the major product of this cell type?

35. ID major product of this cell type? • First what is the cell? • Note “cartwheel” appearance of nucleus • Lots of RER and Golgi • Nucleus not centrally located • THIS IS A PLASMA CELL • What do plasma cells make? Antibodies!

36. Identify

37. Hints: • Size of cell • Multi-lobed nucleus MEGAKARYOCYTE

38. Identify

39. Hints: • It has a germinal center evident and its dark purple • Look at the epithelium! • PHARYNGEAL TONSIL because of the pseudostratified columnar epithelium

40. Identify

41. Continuous capillary • Notice endothelial cell and pericyte (shared basal lamina)

42. Identify

43. Hints: • Epithelium • Germinal center • PALATINE TONSIL • Ideally you would look at the epithelium all the way around to make sure there was no pseudostratified columnar

44. Identify what is indicated

45. Its part of a tonsil • It’s a big gap • It’s a crypt!

46. The Thymus • Allograft • Isograft • What is the basis for allograft rejections?

47. The Thymus • Allograft • Tissue graft between members of the same species but different genetics • Isograft • Tissue graft between members within a single species with the same genetic identity • What is the basis for allograft rejections? • MHC class I antigens

48. Nude Mice • The thymus is responsible for T cell existance. • Athymicno T cells • No allograft rejection Feels exposed

49. Thymus • Located just above the aortic arch • ENCAPSULATED • Multilobulated • Each lobule has cortical and medullary portion • Hassall’s corpuscles present – these are the key

50. More lovely thymus • What happens in the thymus • Where are T-cells “born”? • How do T cells get into the thymus?