Background: The diagnosis of Adult T-cell leukemia/lymphoma ATLL subtypes in human T-lymphotropic virus type I (HTLV-I) carriers based in morphology and immunophenotype of lymphocytes can be challenger. We propose that polymerase chain reaction (PCR) amplification of the rearranged TCR gene in HTLV-I healthy carriers would be a convenient method for establishing the nature of the circulating T lymphocytes in asymptomatic HTLV-I carriers, presenting only mild and inconclusive signals of deviation from normality.
Methods: Using PCR, we analyzed the genetic recombination pattern of the T-cell beta-chain receptor gene (TCR-beta) in order to identify clonal expansion of peripheral blood T lymphocytes in 17 HTLV-I-positive healthy carriers and in nine normal HTLV-I-negative blood donors. To evaluate the performance of PCR in detection of clonality, we also analyzed 18 patients with post-thymic/mature T-cell malignancies presenting circulating abnormal lymphocytes.
Results: Seven of the 17 HTLV-I positive individuals presented circulating abnormal lymphocytes; monoclonal or oligoclonal expansion of T-cells was detected in five of the 17 HTLV-I-positive individuals, all of them presenting abnormal lymphocytes. Clonal expansion was not detected in any of the negative controls or in any of the 12 remaining healthy carriers. All patients in the positive control group tested positive by PCR and Southern blots. Southern blots were negative for all 17 healthy carriers.
Conclusions: PCR amplification of segments of rearranged TCR-beta is reliable for allowing early detection of small populations of clonal T cells in blood samples from asymptomatic HTLV-I carriers, providing an additional alert in the follow-up of carriers with abnormal circulating lymphocytes.