DEMONSTRATION OF HUMAN T-LYMPHOTROPIC VIRUS TYPE-I (HTLV-I)-SPECIFIC T-CELL RESPONSES FROM SERONEGATIVE AND POLYMERASE CHAIN REACTION-NEGATIVE PERSONS EXPOSED TO HTLV-I

Human T lymphotropic virus type I (HTLV-I) is a human retrovirus etiol ogically linked to adult T cell leukemia and the progressive chronic n eurologic disease HTLV-I-associated myelopathy/tropical spastic parapa resis. Described is a method that measures the production of interleuk in-2 from HTLV-I synthetic peptide-stimulated peripheral blood lymphoc ytes (PBL) of HTLV-I-infected persons. The peptides correspond to immu nogenic regions of the HTLV-I Env and Tax proteins. Significantly, thi s assay demonstrated T cell responses to these HTLV-I peptides from co ded PBL samples in 7 of 19 HTLV-I-seronegative polymerase chain reacti on-negative persons known to have been exposed to HTLV-I but in none o f 16 matched controls without risk factors for exposure (P = .007). Th e implications of this finding are discussed.