Radioimmunoassay of class-specific antibodies (RIACA): chicken antibodies to DNP.

A radioimmunological method for the quantitation of class-specific antibodies has been developed. The method allows the quantitation of nanogram per ml concentrations of IgG- and IgM-anti-DNP antibodies without any physical or chemicadioimmunoassay of class-specific antibodies (RIACA) against BSA (Viljanen et al., 1975) developed recently by us. DNP was coupled covalently to a cyanogen bromide activated paper disk with the augmentation of lysine molecule. Anti-DNP antibodies were allowed to react with the coupled DNP and then quantitated by their capacity to bind 125I-labeled anti-chicken-mu or anti-chicken-gamma. The inter-assay variation coefficients ranged from 8.1 to 14.7% and the mean standard deviations of duplicate determinations were about 11%. The combination of this method with the exact immunoradiometric quantitation of the total serum IgM and IgG, and with an immunoabsorption technique, makes possible to quantitate class-specific antibodies in weight units.