Transplant rejection

Transplant rejection

1. TRANSPLANT REJECTION Presented by: Dr. D. Vamshikrishna MD (H)

2. What is Transplant rejection? Transplant rejection  is process in which the transplanted tissue (of donor) is rejected by the recipient's immune system and may result in fatal illness if not treated/removed early.

3. Based on genetic relationship between donor and recipient there are four types of Grafting methods: 1. Autografts are grafts in which the donor and recipient is the same individual. 2. Isografts are grafts between the donor and recipient of the same genotype. 3. Allografts are those in which the donor is of the same species but of a different genotype. 4. Xenografts are those in which the donor is of a different species from that of the recipient.

4. For any successful tissue transplant without immunological rejection, matched Major Histocompatibility Locus Antigens (HLA) between the donor and recipient are of paramount importance. The greater the genetic disparity between donor and recipient in HLA system, the stronger and more rapid will be the rejection reaction.

5. All types of grafts have been performed in human beings but xenografts have been found to be rejected invariably due to genetic disparity. Most commonly practiced grafting are: Skin grafting Kidney Bone marrow transplantation .

6. Exceptions in Rejections: Cornea transplants are rarely rejected because the cornea has no blood supply. Also, transplants from one identical twin to another are almost never rejected.

7. Graft versus Host Reaction In some cases esp. when the transplanted tissue is bone marrow, a peculiar illness arises besides rejection of the transplanted bone marrow called GRAFT Vs HOST REACTION. The intensity of GVH reaction depends upon the extent of genetic disparity between the donor and recipient.

8. The clinical features of Graft Vs Host reaction include: Fever, Weight Loss, Anaemia, Dermatitis, Diarrhoea, Intestinal Malabsorption, Pneumonia, Hepatosplenomegaly.

9. MECHANISMS OF GRAFT REJECTION Except for autografts and isografts, an immune response against allografts is inevitable/unavoidable. The development of immunosuppressive drugs has made the survival of allografts in recipients possible. Rejection of allografts involves both cell-mediated and humoral immunity.

10. 1. CELL-MEDIATED IMMUNE REACTIONS Mainly responsible for graft rejection and are mediated by T cells (mainly by cytotoxic T cells) . T cells attack the graft and destroy it.

11. 2. HUMORAL IMMUNE REACTIONS In addition to the cell-mediated immune reactions, humoral antibodies cause certain rejection reactions.

12. TYPES OF REJECTION REACTIONS Based on the underlying mechanism and time period, rejection reactions are classified into 3 types: 1- Hyperacute Rejection 2- Acute Rejection 3- Chronic Rejection

13. 1. HYPERACUTE REJECTION Hyperacute rejection appears within minutes to hours of placing the transplant and destroys it. It is mediated by Humoral system antibodies. This type of rejection is seen when a recipient is given the wrong type of blood. For example, when a person is given type A blood when he or she is type B.

14. 2. ACUTE REJECTION This usually becomes evident within a few days to a few months of transplantation. Acute graft rejection may be mediated by cellular or humoral mechanisms.

15. 3. CHRONIC REJECTION Chronic rejection may develop slowly over a period of months to a year or so. The underlying mechanisms of chronic rejection may be immunologic or ischaemic . Patients with chronic rejection of renal transplant show progressive deterioration in renal function as seen by rising serum creatinine levels.

16. How to overcome transplant rejection? Tissue typing is done to prevent transplant rejection Here both the organ donor and the person who is receiving the organ tissue typing is done to ensure that the organ or tissue is as similar as possible to the tissues of the recipient. The more similar the antigens are between the donor and recipient, the less likely that the organ will be rejected. No match is usually 100 percent identical. No two people, except identical twins, have identical tissue antigens.