Question

Nude mice are not resistant to xenografts because of the absence of which cells?

• A. B cells
• B. T cells
• C. Both B and T cells
• D. None

Hint:

Athymic mice lack maturation of which lymphocyte needed for graft rejection?

Answer 1

The Correct Option is B

Step 1: Nude mice carry a mutation that leaves them without a functional thymus, so they cannot generate mature T lymphocytes. Step 2: Without T cells they cannot mount adaptive responses that need CD4 helper and CD8 cytotoxic cells, including graft rejection. Step 3: Because graft rejection of both allografts and xenografts requires CD4+ and CD8+ T cells, the absence of T cells lets transplanted (xenograft) tumours grow without rejection. Step 4: B cells are largely present and the defect is not of both lineages, so the correct answer is absence of T cells.