Quantitation of soluble immune complexes by a microplate Raji cell-ELISA method

A Raji cell microplate-ELISA method has been devised for the detection and quantitation of putative immune complexes present in human sera. The Raji cells immobilized with glutaraldehyde (final concentration 0.67%) were conveniently utilized in the solid phase system. The specific binding of AHG diluted in PBS (without complement) increased linearly in the range of 0.1 to 5 micrograms. The purified human IgG showed some low-affinity binding which was 7-to 14-fold lower than the binding of AHG. The circulating immune complexes positive sera were found to have values above the mean of 11.95 +/- 4.09 micrograms/ml AHG equivalent for normal human sera (n = 72). The method is sensitive, reproducible and it can be performed with simplicity and rapidity.