T-cell suppression prevents transplant rejection

Steps:

• Transplant rejection occurs when the recipient's immune system identifies the donor organ as foreign.
• T-lymphocytes (T-cells) are key players in cell-mediated immunity that attack non-self tissues.
• Immunosuppressive drugs target T-cell activity to block this response.
• This allows the organ to be accepted while balancing infection risk through controlled suppression.

Why D is correct:

• T-lymphocytes drive acute rejection via cytotoxic T-cells that directly kill foreign cells, so their suppression (e.g., via drugs like cyclosporine) prevents organ damage per immunological principles of adaptive immunity.

Why the others are wrong:

• A: B-lymphocytes produce antibodies for humoral immunity, which can contribute to rejection but aren't the primary target for prevention.
• B: Natural active immunity builds long-term protection against pathogens, not transplants, and would worsen rejection.
• C: Natural passive immunity transfers pre-formed antibodies (e.g., from mother to child), irrelevant to suppressing transplant responses.

Final answer: D