Abstract
FUKUDA, K., SEINO, J., KINOSHITA, Y., SUDO, K., HORIGOME, I., SAITO, T., FURUYAMA, T. and YOSHINAGA, K. Circulating Immune Complex-Like Materials Which Bind to Heat Inactivated Clq Interfere with the Clq Solid Phase Assay for Immune Complexes. Tohoku J. exp. Med., 1985, 146 (4), 449-456, - Clq solid phase assay (Clq SP) was devised based on the fact that immune complexes (IC) and aggregated human globulin (AHG) bind to Clq. Neither IC nor AHG was found to bind to heat inactivated Clq. On the other hand, circulating immune complex (CIC)-like materials in patients' sera were able to bind to heat inactivated Clq, indicating that these CIC-like materials are not true CIC. Gel filtration analysis showed that molecular size of such CIC-like materials was almost the same as monomeric IgG, while Lure CIC were in heavy fractions. True CIC did not bind to heat inactivated Clq but bind only to native Clq. The CIC-like activity is not due to rheumatoid factors. About 2/3 of CIC positive sera by Clq-SP are not really CIC positive but are due to interference by the CIC-like materials.
