American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which cytotoxic effect does not typically associate with Mycophenolate mofetil?

1. Impaired thymocyte development

2. Reduced platelet count

3. Increased lymphocyte proliferation

4. Decreased antibody production

The correct answer is: Increased lymphocyte proliferation

Mycophenolate mofetil (MMF) is an immunosuppressive medication primarily used in the context of organ transplantation and autoimmune diseases. Its mechanism of action is largely attributed to the inhibition of lymphocyte proliferation, particularly T and B lymphocytes, by blocking de novo purine synthesis. It specifically inhibits the enzyme inosine monophosphate dehydrogenase (IMPDH), which is crucial for the proliferation of lymphocytes that rely on this pathway for their nucleotide synthesis. Given this, the correct answer cites the cytotoxic effect that does not align with the pharmacological profile of MMF. In fact, MMF suppresses rather than promotes lymphocyte proliferation. This inhibition can lead to effects that might include impaired thymocyte development, a reduced platelet count (thrombocytopenia), and decreased antibody production as a result of lower B cell activity. Thus, the correct answer highlights that mycophenolate mofetil does not associate with increased lymphocyte proliferation, as this contradicts its mechanism of action, which is fundamentally aimed at reducing the immune response, particularly through the limitation of lymphocyte growth and activity.