An improved immunobead test procedure for detecting sperm antibodies in serum

In order to improve the efficiency of IBT screening of sera for sperm antibodies, the use of immunobeads with attached rabbit antibodies directed against whole human immunoglobulin (IBT-GAM) was investigated and compared with the use of separate immunobeads specific for each of the main immunoglobulin classes (IBT-IgG, IBT-IgA, IBT-IgM). Sera found positive by the IBT-GAM procedure were then tested by IBT-IgG, -IgA, and -IgM procedures to determine the immunoglobulin class or classes of the sperm antibody. The new procedure is much more efficient for screening larger batches of sera and gives results identical with those from the old procedure when greater than or equal to 50% sperm coating is used as criterion of positivity. We now use the IBT-GAM procedure for initial screening of all sera, followed by further testing of positive sera on the same preparation to determine the immunoglobulin class or classes of the antibody.