Question

In which situation would the tissue from a donor not be rejected?

a. Known exposure of the donor within the last 12 months to HIV
b. Documented diagnosis of Hepatitis A
c. Current diagnosis of Hepatitis B
d. Donor known to have received transplant of human dura mater.

Answer 1

A donor's tissue would not be rejected in the case of an isograft between monozygotic twins, due to their genetically identical MHC proteins, reducing the risk of transplant rejection.

Step-by-step explanation:

The tissue from a donor would not be rejected in the specific case of an isograft, where tissue from one monozygotic (identical) twin is transplanted to another. Since the twins are genetically identical, their major histocompatibility complex (MHC) proteins, also referred to as human leukocyte antigens (HLAs), are the same. Therefore, the transplanted tissue would not be recognized as foreign by the recipient's immune system, which significantly reduces the risk of transplant rejection.

Under normal circumstances, the recipient's immune system may recognize donor tissue that expresses different MHC molecules as foreign, triggering an immaaiune response. This leads to the rejection of the transplanted organ or tissue. The cytotoxic T cells of the immune system will attack the donated tissue if it does not closely match the MHC of the recipient. To avoid this, matching MHC types and immunosuppressive therapy are critical in transplant procedures.