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

Mycophenolate mofetil has effects on which type of immune cells primarily?

1. B cells

2. T cells

3. Both B and T cells

4. Natural killer cells

The correct answer is: Both B and T cells

Mycophenolate mofetil is an immunosuppressive drug that exerts its effects primarily by inhibiting the proliferation of lymphocytes, which includes both T cells and B cells. The active metabolite, mycophenolic acid, acts by selectively inhibiting an enzyme called inosine monophosphate dehydrogenase (IMPDH). This enzyme is crucial in the de novo pathway of purine synthesis, which is particularly important for lymphocytes because they rely heavily on this pathway for rapid proliferation. T cells and B cells both require the synthesis of nucleotides for cell division and growth, especially when responding to antigens. Mycophenolate mofetil's effects on inhibiting lymphocyte proliferation make it particularly effective in preventing graft rejection and managing autoimmune diseases, where both T and B cells play significant roles. On the other hand, natural killer cells, which are a component of the innate immune system, primarily rely on different pathways for their function and proliferation. Therefore, mycophenolate mofetil does not have a primary effect on them, making the answer that it affects both B and T cells the most accurate representation of its immunosuppressive capabilities.