T-LYMPHOCYTES IN CHRONIC MYELOGENOUS LEUKEMIA (CML) - NO EVIDENCE OF THE BCR/ABL FUSION GENE DETECTED BY FLUORESCENCE IN-SITU HYBRIDIZATION IN 14 PATIENTS

Previous studies designed to identify the Ph chromosome in T lymphocytes from patients with chronic myelogenous leukaemia (CML) were mostly based on small numbers of patients. To examine the possibility that the occasional CML patient might have major penetration of the T-cell compartment by the leukaemic clone, we studied interphase T cells from the blood of 11 CML patients conventionally treated in chronic phase and three in relapse after allogeneic bone marrow transplant (BMT) by fluorescence in situ hybridization using BCR and ABL cosmid probes. Granulocytes from the same patient and cells from the SD-1 CML cell line served as positive controls. Cells with juxtaposition of BCR and ABL signals or with the two signals up to one signal diameter apart were scored as positive. In each CML patient the incidence of 'positive' T cells was much less than in positive controls and similar to that found in negative controls (mean values +/- 1 SD: 7.7 +/- 3.6; 91.2 +/- 3.1, and 5.6 +/- 2.2, respectively). We conclude that none of the patients studied by this technique had any appreciable proportion of BCR/ABL-positive T cells in the circulation.