Transplant Rejection and Immunity

The correct answer is E.

 
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"ABO incompatibilities are hazardous because of the presence of natural anribodies in recipients and the normal expression of A and B blood group substances on endothelium, resulting in immediate vascular injury."

Types of graft rejection:

Hyperacute -extremely rapid rejection (hours) occlusion of graft vessels
Hyperacute rejection is mediated by pre-existing antibodies against donor antigens

Acute - days to weeks after transplant cell-mediated immune response
Acute rejection is based on development of an adaptive immune response


Chronic -months to years after transplant graft vascular disease


The patient is suffering from hyperacute rejection due to the preformed anti-B ABO blood group antibody found in all type A positive individuals. Hyperacute rejection occurs within minutes to a few hours of the time of transplantation, and is due to the destruction of the transplanted tissue by preformed antibodies reacting with antigens found on the transplanted tissue that activate complement and destroy the target tissue. Preformed antibodies can also be due to presensitization to a previous graft, blood transfusion, or pregnancy.


Acute rejection due to antibody-mediated immunity (choice A) is incorrect because this patient suffered from hyperacute rejection (immediate) occurring within minutes to hours, rather than days.

Acute rejection due to cell-mediated immunity (choice B) will not occur until several days or a week following transplantation. Acute rejection is due to type II and type IV reactions.


Chronic rejection, due to the presence of cell-mediated immunity to minor HLA antigens (choice C), occurs in allograft transplantation months to even years after the transplant. Chronic rejection is generally caused by both humoral and cell-mediated immunity.

An accelerated acute rejection, occurring in 3-5 days, can be caused by tissue infiltration and destruction by presensitized T lymphocytes and macrophages (choice D) and/or antibody-dependent, cell-mediated cytotoxicity (ADCC). Note that this is not a hyperacute reaction.

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