1. 1 Bo Gao, Ph.D. DEPARTMENT OF IMMUNOLOGY INSTITUTE FOR IMMUNOBIOLOGY 2010-6-28 Email: gb1112@163.comgb1112@163.com Tel: 54237379

2. 2 Dream of Paranoia Dream of Paranoia Dream of excellent surgeon who wants to excel himself. Dream of excellent surgeon who wants to excel himself. Dream of excellent scientist who believe nothing is impossible. Dream of excellent scientist who believe nothing is impossible. Transplantation is a Dream?

3. 3 Can you imagine?

4. 4 Contents:  Introduction  Immunologic Basis of Allograft Rejection  Classification and Effector Mechanisms of allograft rejection  Prevention and Treatment of Allograft Rejection  Xenotransplantation

5. 5 Introduction

6. 6  Transplantation: the process of taking cells, tissues, or organs called a graft (transplant), from one part of individual and placing them into another (usually different individual).  Donor: the individual who provides the graft.  Recipient or host: the individual who receives the graft.

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9. 9 Inbred mouse strains - all genes are identical

10. 10  The cells of allograft will express alloantigens which are recognized as foreign by the recipient.

11. 11  A xenograft is generally rapidly rejected by the recipient.

12. 12 Nobel Prize in Physiology or Medicine 1912 Alexis Carrel (France) Alexis Carrel (France) Work on vascular suture and the transplantation of blood vessels and organs Work on vascular suture and the transplantation of blood vessels and organs Great events in history of transplantation Experimental kidney transplantation -1912

13. 13 Nobel Prize in Physiology or Medicine 1960 Peter Brian Medawar (1/2) Peter Brian Medawar (1/2) Discovery of acquired immunological tolerance Discovery of acquired immunological tolerance – The graft reaction is an immunity phenomenon – 1950s, induced immunological tolerance to skin allografts in mice by neonatal injection of allogeneic cells Great events in history of transplantation Medawar (1945): the graft reaction is an immunity phenomenon

14. 14 Nobel Prize in Physiology or Medicine 1980 George D. Snell (1/3), Jean Dausset (1/3) George D. Snell (1/3), Jean Dausset (1/3) Discoveries concerning genetically determined structures on the cell surface that regulate immunological reactions Discoveries concerning genetically determined structures on the cell surface that regulate immunological reactions – H-genes (histocompatibility genes), H-2 gene – Human leukocyte antigens (HLA) ----MHC Great events in history of transplantation Discovery of MHC

15. 15 Nobel Prize in Physiology or Medicine 1990 Joseph E. Murray (1/2) Joseph E. Murray (1/2) Discoveries concerning organ transplantation in the treatment of human disease Discoveries concerning organ transplantation in the treatment of human disease – In 1954, the first successful human kidney transplant was performed between twins in Boston. – Transplants were possible in unrelated people if drugs were taken to suppress the body's immune reaction Great events in history of transplantation 1954 First long-term successful RT(Twin)

16. 16 Nobel Prize in Physiology or Medicine 1988 Gertrude B. Elion (1/3), George H. Hitchings (1/3) Gertrude B. Elion (1/3), George H. Hitchings (1/3) Discoveries of important principles for drug treatment Discoveries of important principles for drug treatment – Immunosuppressant drug (The first cytotoxic drugs) ----- azathioprine Great events in history of transplantation Discovery of Immunosuppressant drug

17. 17  T oday, kidney, pancreas, heart, lung, liver, bone marrow, and cornea transplantations are performed among non-identical individuals with ever increasing frequency and success.

18. 18 Skin from an inbred mouse grafted onto the same strain of mouse Skin from an inbred mouse grafted onto a different strain of mouse ACCEPTED REJECTED Genetic basis of transplant rejection Inbred mouse strains - all genes are identical Transplantation of skin between strains showed that rejection or acceptance was dependent upon the genetics of each strain

19. 19 Grafts rejection is a kind of specific immune response Grafts rejection is a kind of specific immune response – Specificity – Immune memory Grafts rejection Grafts rejection – First set rejection – Second set rejection Immunological basis of graft rejection

20. 20 6 months Primary rejection of strain skin e.g. 10 days Secondary rejection of strain skin e.g. 3 days Primary rejection of strain skin e.g. 10 days Naïve mouse Lyc Transfer lymphocytes from primed mouse Immunological basis of graft rejection Transplant rejection is due to an antigen- specific immune response with immunological memory

21. 21 Immunologic Basis of Allograft Rejection

22. 22  Major histocompatibility antigens (MHC molecules)  Minor histocompatibility antigens  Other alloantigens I. Alloantigens

23. 23 1. Major histocompatibility antigens  Main antigens of grafts rejection  Difference of HLA types is the main cause of human grafts rejection  Cause fast and strong rejection

24. 24 2. Minor histocompatibility antigens  Also cause grafts rejection, but slow and weak  Mouse H-Y antigens encoded by Y chromosome  HA-1 ～ HA-5 linked with non-Y chromosome

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26. 26 3. Other alloantigens  Human ABO blood group antigens  Some tissue specific antigens Skin ＞ kidney ＞ heart ＞ pancreas ＞ liver Skin ＞ kidney ＞ heart ＞ pancreas ＞ liver VEC antigen (vascular endothelial cell) VEC antigen (vascular endothelial cell) SK antigen SK antigen

27. 27  Why alloantigens can elicit strong rejection reactions ?  Alloantigens elicit both cell-mediated and humoral immune responses, eventually leading to the disruption of grafts.

28. 28  Many T cells can recognize allogeneic MHC molecules. T cells of the recipient recognize the allogenetic MHC molecules  10 -5 -10 -4 of specific T cells recognize conventional antigens.  1%-10% of T cells recognize allogeneic MHC molecules.

29. 29  Direct Recognition  Indirect Recognition T cells of the recipient recognize the allogeneic MHC molecules

30. 30 Direct Recognition  T cell recognizes an intact allogeneic MHC molecule on graft.

31. 31 Indirect recognition  Uptake and presentation of allogeneic donor MHC molecules by recipient APC in “normal way”  Recognition by T cells like conventional foreign antigens

32. 32 Difference between Direct Recognition and Indirect Recognition Direct Recognition Indirect Recognition Allogeneic MHC molecule Intact allogeneic MHC molecule Peptide of allogeneic MHC molecule APCs Recipient APCs are not necessary Recipient APCs Roles in rejection Acute rejection Chronic rejection Degree of rejection VigorousWeak

33. 33  As mentioned above, alloreactive T cells in the recipient can be activated by both pathways, and these T cells will migrate into the graft.  What role will these activated T lymphocytes play in the rejection response?

34. 34 Role of CD4 ＋ T cells in the rejection response  Activated CD4+T by direct and indirect recognition  CK secretion  MΦ activation and recruitment  Damage grafts by reactions that resemble delayed-type hypersensitivity (DTH)

35. 35  Activated CD8 + T by direct recognition can directly Kill the graft cells, which express the allogeneic calss I MHC molecules. Role of CD8 ＋ T cells in the rejection response

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37. 37  Important role in hyperacute rejection (Preformed antibodies) (Preformed antibodies)  Complements activation  Antibody-dependent cellular cytotoxicity (ADCC)  Opsonization Humoral immunity in rejection response Humoral immunity in rejection response

38. 38 KIR can’t recognize allogeneic MHC on graft KIR can’t recognize allogeneic MHC on graft CKs secreted by activated Th cells can promote NK activation CKs secreted by activated Th cells can promote NK activation Role of NK cells Role of NK cells

39. 39 Classification and Effector Mechanisms of Allograft Rejection

40. 40  Host versus graft reaction (HVGR) Conventional organ transplantation Conventional organ transplantation  Graft versus host reaction (GVHR) Bone marrow transplantation Bone marrow transplantation Immune cells transplantation Immune cells transplantation Classification of Allograft Rejection

41. 41 I. Host versus graft reaction (HVGR)  Chronic rejection Hyperacute rejection  Hyperacute rejection Acute rejection  Acute rejection

42. 42  Occurrence time – Occurs within minutes to hours after host blood vessels are anastomosed to graft vessels  Pathology – Thrombotic occlusion of the graft vasculature – Ischemia, denaturation, necrosis 1. Hyperacute rejection

43. 43 – Preformed antibodies Antibody against ABO blood type antigen Antibody against ABO blood type antigen Antibody against VEC antigen Antibody against VEC antigen Antibody against HLA antigen Antibody against HLA antigen Mechanisms – Complement activation Endothelial cell damage Endothelial cell damage – Platelets activation Thrombosis, vascular occlusion, ischemic damage Thrombosis, vascular occlusion, ischemic damage 1. Hyperacute rejection

44. 44 1. Hyperacute rejection

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46. 46  Hyperacute rejection of a kidney allograft with endothelial damage, platelet and thrombin thrombi, and early neutrophil infiltration in a glomerulus. 1. Hyperacute rejection

47. 47  CD4 + T cells, CD8 + T cells and antibodies may contribute to acute rejection. 2. Acute rejection  Occurrence time  Occurs within days to 2 weeks after transplantation, 80-90% of cases occur within 1 month.  Pathology  Acute rejection is a process of vascular and parenchymal injury mediated by T cells and antibodies.

48. 48  Antibodies can also mediate acute rejection if a graft recipient mounts a humoral immune response to vessel wall antigens.  The antibodies that are produced bind to the vessel wall and activate complement. Mechanisms  DTH-like reaction mediated by CD4 + Th1  Killing of graft cells by CD8 + Tc  Parenchymal cell damage  Vasculitis 2. Acute rejection

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50. 50  Acute rejection of a kidney with inflammatory cells in the interstitium and between epithelial cells of the tubules. 2. Acute rejection

51. 51  Occurrence time – Develops months or years after acute rejection reactions have subsided  Pathology – Fibrosis and vascular abnormalities with loss of graft function 3. Chronic rejection

52. 52 – Not clear – Extension and results of cell necrosis in acute rejection – Chronic inflammation mediated by CD4+T cell/M Φ – Organ degeneration induced by non immune factors Mechanisms 3. Chronic rejection

53. 53 1.Macrophage-T cell mediated 2. Chronic DTH reaction injury of vessel wall 3. Proliferation of smooth muscle cell and luminal occlusion

54. 54 Kidney Transplantation----Graft Rejection

55. 55  Chronic rejection in a kidney allograft with arteriosclerosis 3. Chronic rejection

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57. 57 II.Graft versus host reaction (GVHR)  Graft versus host reaction (GVHR) – Allogeneic bone marrow transplantation – Rejection to host alloantigens – Mediated by immune competent cells in bone marrow A disease caused by GVHR, which can damage the host  Graft versus host disease (GVHD )

58. 58  Graft versus host disease II.Graft versus host reaction (GVHR)

59. 59 Conditions  Enough immune competent cells in grafts  Immunocompromised host  Histocompatability differences between host and graft II.Graft versus host reaction (GVHR)

60. 60  Bone marrow transplantation  Thymus transplantation  Spleen transplantation  Blood transfusion of neonate  In most cases the reaction is directed against minor histocompatibility antigens of the host. II.Graft versus host reaction (GVHR)

61. 61 1. Acute GVHD  Endothelial cell death in the skin, liver, and gastrointestinal tract  Rash, jaundice, diarrhea, gastrointestinal hemorrhage  Mediated by mature T cells in the grafts

62. 62  Acute graft-versus-host reaction with vivid palmar erythema  Acute graft-versus-host reaction with vivid palmar erythema

63. 63 2. Chronic GVHD  Fibrosis and atrophy of one or more of the organs without evidence of acute cell death.  Eventually complete dysfunction of the affected organ and may be fatal.

64. 64  Early, chronic graft-versus-host reaction with widespread, almost confluent hyperpigmented lichenoid papules and toxic epidermal necrosis-like appearance on knee.  Late, chronic graft-versus-host reaction with hyperpigmented sclerotic plaques on the back.

65. 65 Prevention and Therapy of Allograft Rejection

66. 66 Tissue Typing Tissue Typing Immunosuppressive Therapy Immunosuppressive Therapy Induction of Immune Tolerance Induction of Immune Tolerance

67. 67 I. Tissue Typing ABO and Rh blood typing ABO and Rh blood typing Crossmatching (Preformed antibodies) Crossmatching (Preformed antibodies) HLA typing HLA typing – HLA-A and HLA-B – HLA-DR

68. 68 II. Immunosuppressive Therapy Cyclosporine(CsA), FK506 Cyclosporine(CsA), FK506 – Inhibit NFAT transcription factor Azathioprine, Cyclophosphamide Azathioprine, Cyclophosphamide – Block the proliferation of lymphocytes Ab against T cell surface molecules Ab against T cell surface molecules – Anti-CD3 mAb----Deplete T cells Anti-inflammatory agents Anti-inflammatory agents – Corticosteroids----Block the synthesis and secretion of cytokines

69. 69 Removal of T cells from marrow graft

70. 70 III. Induction of Immune Tolerance Inhibition of T cell activation Inhibition of T cell activation – Soluble MHC molecules – CTLA4-Ig – Anti-IL2R mAb Th2 cytokines Th2 cytokines – Anti-TNF- α ， Anti-IL-2 ， Anti-IFN- γ mAb Microchimerism Microchimerism – The presence of a small number of cells of donor, genetically distinct from those of the host individual

71. 71 Part IV Xenotransplantation

72. 72 Lack of organs for transplantation Lack of organs for transplantation

73. 73 From which animals are we able to transplant organs 1. The Chimpanzee: Its DNA sequence differs from ours by only 2% 2. The Baboon: Its organs are too small for a large adult human 3. The Pig: Surprisingly similar to our anatomy and physiology

74. 74 Hyperacute xenograft rejection (HXR) Hyperacute xenograft rejection (HXR) – Human anti-pig nature Abs reactive with Gal α 1,3Gal – Construct transgenic pigs expressing human proteins that inhibit complement activation Delayed xenograft rejection (DXR) Delayed xenograft rejection (DXR) – Acute vascular rejection – Incompletely understood T cell-mediated xenograft rejection T cell-mediated xenograft rejection

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