Studies on vasculitis. VII. C-reactive protein as a substance perpetuating chronic vasculitis. Occurrence in lesions and concentrations in sera.

Previous findings were confirmed that C-reactive protein (C-RP) occurs in some vasculitis lesions, particularly those infiltrated mainly by neutrophils (necrotizing vasculitis). The C-RP was usually in lesions also containing complement C1 or C3c, and in some, IgG was present. Using a procedure that reliably detected 200 ng C-RP/ml serum, C-RP was found in sera of many normal persons, and the amount was influenced by the occupation of the donor. Sera of thirty-one persons with vasculitis with mainly mononuclear cell-infiltrated lesions had about four-fold more C-RP (mean 28, 200 ng/ml serum) than found in normal persons, and sera of thirty-nine persons with mainly neutrophil-infiltrated lesions had eight times the normal amount (mean 56,400 ng C-RP/ml). The amount of C-RP was influenced by the severity, extent and duration of the disorder in most patients. Experimental data suggests that C-RP may contribute to the perpetuation of inflammation in chronic vasculitis.