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

What kind of rejection involves both T cells and B cells in response to a donor organ?

1. Chronic rejection

2. Hyperacute rejection

3. Acute rejection

4. Allergic reaction

The correct answer is: Acute rejection

The type of rejection that involves both T cells and B cells is acute rejection. This form of rejection typically occurs days to weeks after transplantation and results from the recipient’s immune system recognizing the donor tissue as foreign. In acute rejection, T cells (cell-mediated immunity) play a crucial role by attacking the transplanted cells directly, while B cells contribute by producing antibodies against donor antigens, leading to further injury of the transplanted tissue. This response can occur in two phases: a sensitization phase, where the immune system recognizes foreign antigens, and an effector phase, where an aggressive immune attack is mounted against the transplant. In contrast, hyperacute rejection occurs almost immediately after transplantation and is primarily due to pre-existing antibodies in the recipient that react against donor antigens, leading to rapid organ failure without the involvement of T cells and B cells in a synchronous manner. Chronic rejection involves a gradual process driven mostly by T cell activity over months or years, with a complex interplay of immune and non-immune factors, resulting in tissue fibrosis and functional decline. Allergic reactions are not related to organ transplantation and involve responses typically mediated by antibodies against environmental antigens, not specifically in the context of organ transplants.