Transmission of human T-lymphotropic virus type I by blood components from a donor lacking anti-p24: a case report. The Transfusion Safety Study Group.

The present criteria for confirmation of human T-lymphotrophic virus types I and II (HTLV-I/II) infection in blood donors are based on seroreactivity to p24 (gag) and gp46 and/or gp61 (env) on Western blot (WB) and radioimmunoprecipitation assays (WB/RIPA). Any single band and other combinations are classified as indeterminate. This case report documents infection in a donor with a repeatedly indeterminate pattern. The blood donor was anti-HTLV-I/II positive on enzyme-linked immunoassay, and two sera taken 5 years apart were WB/RIPA-indeterminate (p19 and gp68 only). His donations in the interval were associated with transmission of HTLV-I to four of the six recipients available for study. Other recipients of blood from donors whose WB/RIPA results were indeterminate by present criteria should be examined to determine if additional patterns are at least occasionally associated with transmission. The likelihood that such donors are infected is important to those who are counseling them and making decisions concerning recipients of their bloody.