Normal Human Serum Derivatives That Inhibit the Tanned Cell Hemagglutination Test for Rheumatoid Arthritis and Other Reactions

Abstract

With the exception of albumin, the major Cohn plasma fractions and the derivatives of normal human serum obtained by ultracentrifugation in high density salt solutions and by electrophoresis on Geon inhibit the tanned cell reaction with rheumatoid serum. Native γ-globulin is a poor inhibitor but heating increased its inhibitory activity 4000-fold. The most potent inhibitors were those rich in low-density (β) lipoprotein; lipoprotein-poor α- and β-globulins also possessed appreciable inhibitory activity. A large proportion of inhibition found in normal serum was recovered in the middle fraction obtained by ultracentrifuging β-lipoprotein-depleted serum in a 1.21 density salt solution; a slowly sedimenting (small molecule?) component of great inhibitory activity may therefore also be present. Inhibition by the unheated fractions is not specific for the rheumatoid reaction; serum and several of its ultracentrifugal and electrophoretic fractions were examined and found to inhibit the tanned cell test for trichinosis. Inhibition by serum and several derivatives of lectin agglutination of sheep cells further demonstrated the nonspecificity of the inhibition.