#{149}

Covalent binding of y chains of lgG, whole IgA, and j chains of 1gMon polytunctional hydrophilic microspheres (MS) yields MS-lg conjugates, usable as reagents in new microparticle-enhanced nephelometric immunoassays (Nephelia#{174}).The principle of the assays is inhibition by free analyte (lgG, IgA, and 1gM) of agglutination of the MS-lg conjugate with specific antiserum, the light scat-tered by the aggregates being measured with a nephe-lometer. The immunoglobulin assays developed are easy to perform (single-step assays, no washing or phase separation) and sensitive (high dilution of biological sam-ples to exclude interferences and pretreatment). Analyti-cal recovery results (95.4-i 01.2%) and correlations with generally used commercial assays (r = 0.86-0.98) indi-cate that the assays are accurate for large concentratio