Reaction of Rheumatoid Sera with Fragments of Papain-Digested Rabbit Gamma Globulin.

Abstract

Comparison of fragments obtained from chromatography of papain-digested rabbit gamma-globulin on CM-cellulose (FI, FII, FIII in order of chromatographic elution) for reactivity with sera from rheumatoid arthritics indicates that the order of reactivity is FIII > FII > FI. Hemagglutination tests using tanned sheep RBC coated with the proteins gave titers of < 128 for cells coated with FI or FII and a titer of 1:448 for Fin-coated RBC as compared to 1:896 for cells coated with intact gamma-globulin. In hemagglutination-inhibition tests using RBC coated with undigested gamma-globulin and the soluble proteins as inhibitors, FIII produced complete inhibition using 0.01 mg while 0.5 mg of FII produced only partial inhibition and 0.5 mg of FI produced no detectable inhibition. The results indicate that FIII, which contains most of the antigenic determinants of rabbit gamma-globulin, also contains almost all of the structural groupings responsible for reactivity with rheumatoid sera.