Detection of soluble immune complexes by their binding to Fc receptors on mastocytoma cells

Abstract

A mastocytoma cell test for the detection and quantitation of circulating immune complexes is described which is based on the binding of immune complexes to the Fc receptors on the surface of murine mastocytoma cells. Mastocytoma cells were incubated with various dilutions of tested sera or immune complexes prepared in vitro. The cells were subsequently incubated with sheep erythrocytes sensitized by a subagglutinating dose of rabbit anti-sheep erythrocyte serum and then rosette-forming cells were counted. The inhibition of rosette formation indicated the presence of immune complexes in the tested serum. Using this test, we have detected immune complexes prepared in vitro and also soluble immune complexes present in various murine sera. Comparable results were obtained using the Raji cell assay. The mastocytoma cell test is a sensitive and reproducible procedure with several advantages over other currently used procedures.