Transplant rejection occurs when the immune system of a transplant recipient attacks and rejects the donated organ or tissue. There are four types of grafts based on genetic relationship between donor and recipient: autografts, isografts, allografts, and xenografts. For successful transplantation without rejection, matching major histocompatibility locus antigens between donor and recipient is important. Rejection can be avoided by tissue typing to ensure donor and recipient tissues are as similar as possible.

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.

5. • 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.

6. • 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.

7. 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.

8. 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.

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

10. 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.

11. 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.

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

13. 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

14. 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.

15. 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.

16. 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.

17. 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.