Questions: A nurse recalls that an example of an immune-complex-mediated disease is: contact dermatitis. rheumatoid arthritis. bronchial asthma. serum sickness.

The answer is the fourth one (D): serum sickness.

Explanation for each option:

1. Contact dermatitis: This is a type of delayed hypersensitivity reaction (Type IV), not an immune-complex-mediated disease. It occurs when the skin comes into contact with an allergen, leading to an inflammatory response.

2. Rheumatoid arthritis: While rheumatoid arthritis involves immune complexes, it is primarily classified as an autoimmune disease with a significant component of Type III hypersensitivity (immune complex-mediated) and Type IV hypersensitivity (cell-mediated). However, it is not the best example of a pure immune-complex-mediated disease.

3. Bronchial asthma: This is primarily a Type I hypersensitivity reaction, which involves IgE antibodies and mast cells. It is not an immune-complex-mediated disease.

4. Serum sickness: This is a classic example of an immune-complex-mediated disease (Type III hypersensitivity). It occurs when immune complexes (antigen-antibody complexes) are formed in the bloodstream and deposited in various tissues, leading to inflammation and tissue damage.

Summary: Serum sickness is the best example of an immune-complex-mediated disease among the options provided.