Effects of the Rheumatoid Factor and Antigen-Antibody Complexes on the Vessels of the Rat Mesentery

Abstract

Summary The localization and vascular effects of rheumatoid factor, and of antigen-antibody complexes, have been studied in the exposed, living, rat mesentery following intravenous injection of fluoresceinated and unfluoresceinated preparations of these agents, both alone and in combination. Following injection of rheumatoid euglobulin, thrombosis and hemorrhage were observed in the exposed mesentery. Following injection of a chromatographically separated, fluoresceinated 19 S γ-globulin fraction of rheumatoid serum, the vascular changes described were accompanied by a visible layer of fluorescence along the intimal surface of vessel walls. These changes did not occur after injection of a fluoresceinated preparation of Waldenström's macroglobulin. Although soluble antigen-antibody complexes produced no gross vascular changes, a persistent layer of fluorescence was observed along the intimal surface of vessel walls after injection of fluorescent preparations of such complexes. This localization of fluorescence was prevented by prior injection of normal euglobulin, but not rheumatoid euglobulin. When rheumatoid euglobulin preparations and fluorescent antigen-antibody complexes were injected together, the injected fluorescent complexes appeared to be bound in the resulting thrombus, as indicated by fluorescence of the thrombus. Fluorescence due to complexes was not observed in a thrombus produced by application of local mechanical pressure on a vessel. The results described indicate that soluble antigen-antibody complexes and rheumatoid factor, when injected either alone or in combination, are localized at the intimal surface of the vessels of the exposed mesentery. Localization of the complexes is blocked by euglobulin obtained from normal serum but not by rheumatoid euglobulin. These findings suggest that rheumatoid factor and antigen-antibody complexes may play a role in the development of the vascular abnormalities observed in some patients with rheumatoid arthritis.