Which condition is an example of a type IV hypersensitivity reaction?

A type IV hypersensitivity reaction, also known as delayed-type hypersensitivity, is characterized by the immune system's response mediated by T cells rather than antibodies. This type of reaction typically takes hours to days to manifest and involves the accumulation of T lymphocytes and macrophages at the site of the stimulus, leading to inflammation and tissue damage.

Sarcoidosis is indeed an example of a type IV hypersensitivity reaction. It is characterized by the formation of granulomas, which are clusters of immune cells that form in response to persistent antigens. In sarcoidosis, T cells respond to unknown antigens, resulting in the formation of these granulomas primarily in the lungs, but potentially affecting other organs as well. This immune response can cause significant organ dysfunction and is often determined by the presence of activated T cells and macrophages in affected tissues.

In contrast, the other conditions listed involve different mechanisms of immune response. Rheumatoid arthritis is primarily classified as an autoimmune condition with a strong component of type III hypersensitivity. Systemic lupus erythematosus predominantly involves type III hypersensitivity as well, with the formation of immune complexes leading to tissue damage. Goodpasture syndrome is an example of a type II hypersensitivity reaction where antibodies attack the basement membranes in