Reactivity of Globulins from Rheumatoid Sera in the Latex-Fixation Test.

Abstract

Approximately 2/3 of the test rheumatoid sera (62), found to be positive by the latex-fixation test when diluted 1:20, failed to react as whole sera. The removal of albumin by Na2SO4 precipitation restored the demonstrable activity to the reconstituted globulins without reduction of titer. Thus, it was assumed that the inhibiting property of albumin is related to its content in whole serum. Dilution of serum in buffered saline reduced or eliminated this effect so that the flocculating factor or factors present in rheumatoid sera now were measurable. Of equal significance was the observation that reconstituted globulins of 10 sera negative by the conventional latex-fixation test (serum dilution of 1:20) did not react. Although this number of sera is admittedly small, it suggests that the sensitivity of the conventional test is not impaired by the initial 1:20 dilution of serum. Electrophoretic patterns of representative sera substantiated the proposed role of albumin in the reactivity of undiluted sera since the albumin content of the reactive sera was reduced over that recorded for the non-reactive sera (when measured as undiluted serum).