SEMINAL FLUID ANTISPERM ANTIBODIES MEASURED BY DIRECT FLOW-CYTOMETRY DO NOT CORRELATE WITH THOSE MEASURED BY INDIRECT FLOW-CYTOMETRY, THE INDIRECT IMMUNOBEAD TEST, AND THE INDIRECT MIXED ANTIGLOBULIN REACTION

Objective: To compare the direct flow cytometric (FCM) measurement of sperm-bound antibodies with the indirect FCM measurement of unbound an tisperm antibodies in seminal plasma of the same ejaculates. To compar e the FCM measurements with the indirect mixed antiglobulin reaction ( MAR) and the indirect immunobead test (IBT) performed on the same semi nal plasmas. Setting: University hospital-based infertility service. P atients: Eleven infertile men with a positive immunoglobulin (Ig) G di rect MAR test and antibody positivity on the direct FCM measurements. Four control patients with a negative IgG-direct MAR test. Main Outcom e Measures: The proportion of spermatozoa positive for IgG and IgA ant ibodies as measured by various tests. Results: The direct and indirect FCM measurements for sperm-bound antibodies from seminal plasma did n ot correlate with each other. In general, IgG antibodies were not dete ctable by indirect FCM whereas IgA were detected in lower proportions than by direct FCM measurements. Weak correlation was observed between the indirect FCM, indirect MAR, and indirect IBT measurements. Conclu sion: Nearly all of the IgG and some of the IgA antisperm antibodies i n seminal fluid bind to spermatozoa. Thus, indirect tests to measure a ntisperm antibodies from seminal plasma are likely to miss the presenc e of antisperm IgG antibodies while detecting some cases of IgA antibo dies.