Demonstration of circulating and tissue-fixed immune complexes in cutaneous necrotizing vasculitis.

Simultaneous demonstration of circulating and tissue-fixed immune complexes was attempted in 22 patients with cutaneous necrotizing vasculitis (7 anaphylactoid purpura, 9 cutaneous allergic vasculitis, 2 livedo reticularis, 1 thrombophlebitis, 2 erythema elevatum diutinum and 1 acute generalized pustular bacterid). In 16 out of the 22 patients, particularly patients with anaphylactoid purpura and cutaneous necrotizing vasculitis, there was a high Clq-binding activity. Decreased levels of C3 and C4 were seen in 2 and 3 patients, respectively. In 11 out of 16 skin lesions, the granular deposits of immunoglobulins and/or complement were demonstrated in the blood vessel walls of the dermis. IgA deposit was seen in anaphylactoid purpura, and IgM deposit in other types of vasculitis. C3 deposit was the most frequently noted. There was no definite correlation between Clq-binding activity and tissue deposits.