A study of the relation of seronegative and seropositive rheumatoid arthritis to each other and to necrotizing vasculitis

Abstract

A clinical-laboratory correlation was made in 136 patients with arthritis diagnosed as rheumatoid arthritis by American Rheumatism Association criteria. Twenty-nine patients were seronegative and 107 seropositive for anti-IgG globulins. The frequency distribution for positive and negative titers for anti-IgG activity suggested that seropositive and seronegative patients may belong to truly distinct serologic populations. Other corollary differences existed in the groups: the IgG level in seropositive patients was most closely correlated with the IgA level, whereas in seronegative patients with arthritis it was most closely correlated with the IgM level; the hemolytic complement titer was lower in the seropositive than in the seronegative patients; and the quantity of precipitable euglobulin was greater in seropositive than in seronegative patients. In the seropositive patients the titer of latex anti-IgG activity showed a weak negative correlation with complement titer. Necrotizing vasculitis occurred exclusively among seropositive patients with higher titers. Serum complement activity was significantly lower in the patients with vasculitis. It seems probable that necrotizing vasculitis is an extreme manifestation of seropositive rheumatoid arthritis, and that necrotizing vasculitis occurs seldom if at all in seronegative rheumatoid arthritis.