Circulating IgG antibodies against factors IX and VIII in multiple sclerosis.

A 64-year-old man with multiple sclerosis developed a circulating anticoagulant. Three immunoglobulin fractions (I = IgG; II =IgG+IgA; III = IgM) were separated from patient serum by 33-percent ammonium sulfate precipitation and DEAE-52 cellulose column chromatography. Fractions I (IgG) and II (IgG+IgA) had factor VIII inhibitory activity on incubation. Fraction I (IgG) possessed, in addition, immediate anti-IX activity which did not require incubation. Absorption studies characterized the VIII inhibitors as IgG-gamma in fraction I and IgG-gamma+IgG-lambda in fraction II. Immediately reactive IgG anti-IX antibodies associated with kinetically distinct IgG anti-VIII antibodies have not been described previously.