Question

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

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

Hint:

Athymic nude mice lack mature T cells, so they cannot reject grafts.

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: Graft rejection of allografts and xenografts is driven by T cells (both CD4 and CD8). Without mature T cells, the animal cannot mount this cell-mediated rejection, so transplanted foreign tissue is accepted rather than destroyed. Step 3: Their B cell compartment is largely intact, but antibody responses to most antigens also need T cell help, so the dominant defect remains the missing T cell. Step 4: Because the question asks why xenografts are not rejected, the single best answer is the absence of T cells, not B cells or both lineages. This is why nude mice are widely used to grow human tumor xenografts.