Plasma anaphylatoxin concentrations in inflammatory skin diseases.

To study the possible involvement of the complement system in inflammatory skin disorders, we measured the concentrations of C3a and C4a anaphylatoxins in the peripheral blood of 148 patients with various inflammatory skin disorders and 48 healthy control subjects by radioimmunoassay. Significant increases in mean levels of both C3a and C4a anaphylatoxins were found in 59 patients with psoriasis. Remarkable increases in both C3a and C4a anaphylatoxins were also noted in some patients with leukocytoclastic vasculitis, urticarial vasculitis or unspecified toxic erythema. On the other hand, elevation of C4a alone was noted in a case of systemic lupus erythematosus. In contrast, using the mean of the normal control +/- 2 S.D., no significant anaphylatoxin elevation was found in 16 patients with pustulosis palmaris et plantaris, 7 with pityriasis rosea, 3 with erythema multiforme, and 3 with erythema nodosum or autoimmune bullous dermatoses.