In cases of cytotoxic antibody-mediated reactions, which condition is an example?

In cytotoxic antibody-mediated reactions, the immune system produces antibodies that target and damage specific cells or tissues, leading to various conditions. Goodpasture syndrome exemplifies this mechanism, as it involves the production of autoantibodies against type IV collagen in the basement membrane of the kidneys and lungs. This results in glomerulonephritis and pulmonary hemorrhage, showcasing the direct cytotoxic effects of these antibodies on the tissues involved.

Goodpasture syndrome is characterized by the presence of anti-glomerular basement membrane antibodies, which bind to the collagen and trigger complement activation, leading to inflammation and damage. This condition highlights the classic example of a type II hypersensitivity reaction, where the antibodies directly attack and destroy the target cells.

In contrast, the other options represent different mechanisms of immune responses. Allergic rhinitis is primarily mediated by IgE antibodies and is an example of type I hypersensitivity. Contact dermatitis is a delayed-type hypersensitivity response, typically mediated by T cells and not by antibodies. Systemic lupus erythematosus, while it involves autoantibodies, predominantly represents complex-mediated tissue damage rather than direct cytotoxicity. Therefore, Goodpasture syndrome stands out as the clear example of a cytotoxic antibody-mediated reaction.