A kidney transplant recipient stops immunosuppressive therapy three years after his surgery. Shortly after stopping therapy, he demonstrated clinical manifestations of kidney failure. Which type of reaction does this represent?

A.    Cushing's Syndrome: This is a condition caused by prolonged exposure to high levels of cortisol, a hormone produced by the adrenal glands. It is not related to kidney transplant or immunosuppressive therapy.

B.    Hypersensitivity Reaction Type I: Also known as an immediate hypersensitivity reaction or an allergy, this type of reaction involves the immune system's exaggerated response to an allergen. Symptoms can range from mild to severe and occur quickly after exposure to the allergen. While allergies can cause various symptoms, they do not specifically represent rejection of a transplanted organ.

C.    Chronic Graft Versus Host Rejection: This term is commonly associated with bone marrow or stem cell transplants. It occurs when immune cells from the donated tissue recognize the recipient's body as foreign and attack various organs or tissues. This process typically happens over a more extended period and is not directly related to the scenario described.

D.    Acute Host Versus Graft Rejection: This occurs when the recipient's immune system recognizes the transplanted organ as foreign and launches an immune response against it. It can happen shortly after transplantation if the recipient's immune system is not adequately suppressed. In this case, stopping immunosuppressive therapy can trigger acute rejection, leading to the failure of the transplanted organ.