Lack of binding between cryoimmunoglobulins, immunoglobulins and fibronectin: implications for immune complex vasculitis

Abstract

SI MMARYImmunc-complex-mcdialed vasculitis is a frequent comptication of rheumatoid arthritis and sysicmtc lupus cr\'thematosus. The mechanism ofdeptisliion olimmunc complexes wtlhin the vessel wall in these diseases remains unknown, bul probably involves other proteins. Fibronectin is a likely candidate since it possesses the ability to bind to collagen, endothelial cells, and pos.sibly itnmunoglobulins and immune tomple.xes. In this study, the binding ortibroneetin to IgG and IgM eryoglobiilins. cold soluble IgM. IgCi. IgG subclasses and IgG fragments was invesiiyatcd in the solution phase. Static light scattering, fluorescence anisotropy. fluorescence intensity, and PHCi precipitation studies were used to investigate binding under ditfcreni conditions of temperature and ionic strength. These studies failed to demonstrate signitieani binding between tibronectin and IgM. IgG. IgG subclasses and IgG fragments under the eonditions studied These findings argue against solution phase binding of Rbroneclin and immunoglobulins contributing to immune complex vasculitis. The possibility of important surface interactions between these proteins has not been ruled out. KeyworcU libronectin eryoimmunoglohulins protein protein interactions

Cryoglobulins and the immunopathological manifestations of autoimmune disease

“…Obviously the in vivo complexes formed between cryoprecipitable IgG3 in general and cryoprecipitable rheumatoid factor of this subclass are still more difficult to dissect. However, it seems likely that immunoglobulin interactions are likely to be more important than fibronectin binding, as was formerly postulated [20]. It is also important to determine the extent to which cryoglobulin production is autonomous or responsive to antigen stimulation by, for example, lipopolysaccharides, since this has implications for the management of human disease [21].…”