Detection of circulating immune complexes with a modified Raji cell technique.

A modification of the Raji cell technique for the detection of circulating immune complexes is described. Raji lymphoid cells bind immune complexes via the C 3 receptor. Prior to incubation with the test serum it is necessary to block the IgG Fc receptor which would interfere with the assay. In the present modification the IgG Fc receptor is blocked with monoclonal IgG myeloma proteins thereby facilitating the detection of C 3 bound immune complexes with fluoresecein-conjugated anti-light chain serum. This modification is presently used in a survey of immune complexes in a number of autoimmune diseases.