An example of immune injury due to deposition of antigen-antibody complexes is which condition?

• A. Acute glomerulonephritis
• B. Bee-sting allergy
• C. Contact dermatitis
• D. Penicillin allergy

Answer: (A)

Immune injury from deposition of antigen–antibody complexes is a type III hypersensitivity reaction. Circulating immune complexes form in response to an antigen and can trap in tissues like the glomeruli of the kidney. Once deposited, they activate complement and recruit inflammatory cells, leading to inflammation and damage to the glomerular structures. This mechanism is classically seen in acute glomerulonephritis, especially poststreptococcal glomerulonephritis, where immune complexes containing streptococcal antigens and antibodies deposit in the glomeruli and cause nephritic inflammation. Hence, acute glomerulonephritis is the best example among these options.

Bee-sting allergy is an IgE-mediated immediate hypersensitivity reaction. Contact dermatitis is a T-cell–mediated delayed-type hypersensitivity. Penicillin allergy is typically an IgE-mediated reaction, though it can involve other pathways, but it does not illustrate immune complex deposition in tissues.