Chronic rejection after transplantation is characterized by which features?

• A. Hyperacute rejection: preformed antibodies
• B. Acute rejection: CD8+ T cells
• C. Chronic rejection: cell-mediated and humoral components with fibrosis months to years after transplant
• D. Graft-versus-host disease: donor T cells attack host

Answer: (C)

Chronic rejection is driven by ongoing low-level immune injury that involves both T cells and antibodies, which over months to years leads to fibrosis and vascular changes in the graft. This combination of cell-mediated and antibody-mediated damage causes progressive scarring and hardening of the transplanted tissue, ultimately impairing function. This is distinct from hyperacute rejection, which happens within minutes to hours due to preformed antibodies causing immediate graft loss, and from acute rejection, which occurs in the weeks to months after transplant and is primarily driven by T cells (with possible antibody involvement). Graft-versus-host disease is a different problem that occurs when donor T cells attack the recipient in bone marrow transplantation.