Question

The major molecules responsible for rejection of transplant is

• A. \( \text{B cells} \)
• B. \( \text{T cells} \)
• C. \( \text{MHC molecule} \)
• D. \( \text{Antibodies} \)

Hint:

Identical twins have the exact same MHC molecules, which is why they can donate organs to each other with zero risk of rejection.

Answer 1

The Correct Option is C

Concept: Organ transplantation success depends on the body's ability to recognize the new tissue as "self" or "non-self."
• This recognition is handled by a set of surface proteins found on almost all nucleated cells.
• These proteins act as identification tags for the immune system.

Step 1: Defining the Identification Proteins.
The proteins responsible are called the Major Histocompatibility Complex (MHC) molecules. In humans, these are also known as Human Leukocyte Antigens (HLA).

Step 2: Mechanism of Rejection.
If the MHC molecules of the donor organ do not match the MHC molecules of the recipient, the immune system detects an "invader." T-cells specifically recognize these foreign MHC molecules and initiate a destructive immune response. Therefore, MHC molecules are the primary molecules that dictate transplant compatibility. Final Answer: The major molecules responsible for the rejection of transplants are MHC molecules.