Differential measurement by ELISA of free and IgA bound α1-microglobulin in human serum without prior fractionation

Two solid phase enzyme immunoassays for the measurement of alpha1-microglobulin (alpha1m) in biological fluids are reported. These assays are complementary and allow the separate determination of free alpha1m and alpha1m bound to IgA without fractionation of the fluids. Specificity, reproducibility and sensitivity of the assays are reported. Differential measurements on normal or pathological sera were compared to the measurements obtained by chromatographic separation of free and bound alpha1m before assay. Results obtained with the enzyme immunoassays were significantly correlated with those obtained by radioimmunoassay.