A microELISA Raji cell assay to detect immune complexes

The Raji cell assay to detect immune complexes has been modified to a microtiter ELISA system. Raji cells were fixed to microplate wells, then reacted with serum samples or aggregated human IgG. Horseradish peroxidase-conjugated anti-human IgG was used to detect bound complexes. There was a linear relationship between aggregated IgG added and optical density reading, with less than 2 micrograms/ml of aggregated IgG readily detected. When applied to human serum this technique gave results comparable to those obtained with the standard Raji cell assay. The Raji micro-ELISA is simpler to perform than the standard assay, is equally reliable, and avoids the hazards of radioactivity.