Stability evaluation of CNBr-Sepharose 4 B for using as solid matrix in immunoradiometric assay antibodies coupling

The present work verifies the stability of a CNBr-Sepharose 4 B product (Pharmacia) stored at our laboratory one year after its expire date in view of its application as solid phase antibodies in the development of an immunoradiometric assay for measurement of serum human proinsulin. From rabbit IgG antiserum previously purified and concentrated by ultrafiltration (Publication IPEN 294, 1990) the antibodies were isolated by affinity chromatography. Sheep antiserum anti-rabbit IgG were coupled to cyanogen bromide activated Sepharose 4 B and the rabbit IgG which were bound to the immunosorbent could be obtained by elution with stepwise pH gradient from pH 7.0 to pH 2.5. The complying efficiency of the sheep antiserum to this solid phase material was 97%. The elution profile obtained shows identify of the sample related to the antiserum anti-rabbit IgG by affinity chromatography. These results suggest that this CNBr-Sepharose 4 B lot can be used satisfactorily to attach antibodies for use in the two-site immunoradiometric assay. (author). 7 refs., 1 fig