What causes acute poststreptococcal glomerulonephritis (APSGN) after a streptococcal infection?

Acute poststreptococcal glomerulonephritis (APSGN) occurs as a result of an immune response following infection with β-hemolytic Streptococcus bacteria, typically after pharyngitis or skin infections. In this condition, the body's immune system generates antibodies to the streptococcal antigens. When these antibodies bind to the antigens, immune complexes form, which can deposit in the glomeruli of the kidneys. This deposition triggers an inflammatory response, leading to the characteristic features of APSGN such as hematuria, proteinuria, and edema.

The involvement of immune complex formation is critical in the pathogenesis of APSGN, distinguishing it from other renal conditions. The underlying mechanism reveals how the infection can lead to renal impairment well after the initial streptococcal infection has resolved, highlighting the immune system's role in causing damage rather than direct bacterial action.

Understanding this aspect clarifies the disorder's development following specific infections and provides insight into potential preventive measures, such as prompt treatment of streptococcal infections to reduce the risk of developing APSGN.