In immune complex associated vasculitis, immune complexes are ______ and extremely ____

In immune complex associated vasculitis, immune complexes are ______ and extremely ____

• A. Identifiable, high
• B. Unidentifiable, low
• C. Unidentifiable, high
• D. Identifiable, low

Answer: (B)

In immune complex–mediated vasculitis the immune complexes form and deposit in small vessel walls, triggering inflammation through complement activation. Because these complexes rapidly leave the circulation to lodge in tissues and are cleared, circulating immune complexes are not easily detectable and exist at very low levels. Tissue usually shows the deposits (IgG/IgM and C3) on biopsy, even though blood tests often fail to reveal high, identifiable complexes. That’s why the correct description is that immune complexes are unidentifiable and extremely low.

In immune complex–mediated vasculitis the immune complexes form and deposit in small vessel walls, triggering inflammation through complement activation. Because these complexes rapidly leave the circulation to lodge in tissues and are cleared, circulating immune complexes are not easily detectable and exist at very low levels. Tissue usually shows the deposits (IgG/IgM and C3) on biopsy, even though blood tests often fail to reveal high, identifiable complexes. That’s why the correct description is that immune complexes are unidentifiable and extremely low.