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 etiologically linked to adult TcellleukemiaandtheprogressivechronicneurologicdiseaseHTLV-I-associatedmyelopathy/tropical spastic paraparesis. Described is a method that measures the production of interleukin-2 from HTLV-I synthetic peptide-stimulated peripheral blood lymphocytes (PBL) of HTLV-I-infected persons. The peptides correspond to immunogenic regions of the HTLV-I Env and Tax proteins. Significantly, this assay demonstrated T cell responses to these HTLV-I peptides from coded PBL samples in 7 of 19 HTLV-I-seronegative polymerase chain reaction-negative persons known to have been exposed to HTL V-I but in none of 16 matched controls without risk factors for exposure (P =.007). The implications of this finding are discussed.