A second discriminator for biological false positive results in enzyme-linked immunosorbent assays for antibodies to human immunodeficiency virus (HTLV-III/LAV).

Two commercially available enzyme-linked immunosorbent assays (ELISA) were compared in screening a large population of volunteer blood donors. One ELISA utilized the human T-lymphotropic virus, Type III (HTLV-III) grown on National Institutes of Health T-lymphocyte cell line, H-9, as antigen source; the second used lymphadenopathy associated virus (LAV) grown on Pasteur Institutes' T-lymphocyte cell line, CEM-F. Biological false positives (BFP) occurred at a rate of approximately 0.5 percent using each antigen source. However, distinct populations of BFP donors were detected when the two antigen sources were compared. Results indicate that at least two separate sets of antigens are recognized in ELISA by our normal population and result in BFP. Sequential utilization of tests using these distinct sources adds a second discriminator to identification of BFP, with the potential for decreasing the requirement for Western blot analysis.