a) To assess the use of "panning" procedures for the detection of antibodies to sperm. b) To develop and use human monoclonal antibodies for the analysis of human transplantation antigens."Panning" assays were developed. The procedures and their use in the analysis of mouse monoclonal antibodies to human sperm are described. B-lymphocytes from individuals sensitized by pregnancy, graft rejection, or blood transfusion were immortalized with Epstein-Barr virus (EBV). Selected sublines producing antibodies to human leukocyte series A (HLA) antigens were fused with mouse myeloma cells and selected clones of hybrid cells secreting monoclonal antibodies were selected.The results of panning assays correlated with those of agglutination assays, but not immunofluorescence or enzyme-linked immunosorbent assays (ELISA). Monospecific and cross-reactive human monoclonal antibodies to HLA antigens were produced.Panning assays can be used for the detection of antibodies to sperm and can be useful where target sperm are of poor motility. The assays may be more sensitive for antibodies to superficial antigens. Human monoclonal antibodies may be used for investigating the identity of, and responses to, transplantation antigens.