Long-term persistence of false positive antibody reactivity in HIV western blot testing of sera from a healthy blood donor.

HIV-Western blot (WB) testing of sequential sera from a blood donor revealed identical bands in the p24 and p55 positions. Additional testing using indirect immunofluorescence antibody technique, radioimmunoprecipitation assay and an HIV p24 antigen immunoassay were negative. During a 5-year follow-up period the blood donor has remained apparently healthy and no signs of disease have developed. We conclude that sera from this blood donor show a false positive HIV WB reactivity. The nature of this reactivity remains obscure but has practical implications for the routine HIV screening of blood donors.