A Two‐Component System of Human Serum Agglutinating Gelatine‐Coated Erythrocytes

Abstract

Summary In normal and pathologic human sera a heat‐labile Anti‐Gelatine Factor could be demonstrated, which agglutinates red cells coated with parent gelatine. In several properties it differs from the collagen antibody observed in rheumatoid arthritis sera and from the experimentally induced rabbit antibody against parent gelatine. By fractionation procedures it could be demonstrated that the Anti‐Gelatine Factor is a two‐component system, consisting of an agglutinator and an activator. The two components showed different solubilities in ammonium sulfate solution. The heat‐labile agglutinator shows in immunoelectrophoresis and gelfiltration properties corresponding to Immunoglobulin M, and precipitates as euglobulin. It possesses a lower agglutinating activity as the whole serum. The serologic reactivity between agglutinator and parent gelatine can be significantly increased by addition of the heat‐stable activator, which by itself possesses no agglutinating activity. It can activate agglutinators from different human sera. Various methods for the inactivation of hemolytic complement had no influence upon the agglutinating activity of the Anti‐Gelatine Factor.