Which is a criterion involving biological compatibility for organ allocation?

• A. Tissue and blood type compatibility
• B. Donor's age
• C. Recipient's height
• D. Hair color

Answer: (A)

The essential idea is immune compatibility in organ transplantation. Tissue typing and ABO blood type matching are used to prevent the recipient’s immune system from attacking the donor organ, which is the main factor that determines whether an organ will be accepted long-term. Blood type compatibility ensures antibodies don’t target donor cells, while tissue compatibility (often assessed through HLA typing and a crossmatch) further reduces the risk of rejection and improves graft survival.

Other factors like the donor’s age, the recipient’s height, or hair color do not influence immunologic compatibility or the likelihood of a successful transplant, so they are not the criteria used for organ allocation based on biological fit.