Lymphoblastic Leukemia Cells at Diagnosis Establishment of Continuous Cultures of T-Cell Acute

ABSTRACTWe have devised methods facilitating the establishment of continuouscultures of T-cell blasts from patients with acute lymphoblastic leukemiaof T-cell type at diagnosis. The cultured cells closely resemble those ofthe patients at the time of diagnosis with respect to surface markers,karyotype, and T-cell receptor gene rearrangements. Cultured T-cellacute lymphoblastic leukemia (diagnosis) cells (a) are lymphocytes witha convoluted nucleus; (b) have doubling times of 24-48 h; (c) aredependent for growth on interleukin 2; (d) are reverse transcriptasenegative; (<•)do not form colonies in methyl cellulose; and (/) are clonalwith respect to T-cell receptor 0 chain rearrangements. Three T-cellacute lymphoblastic leukemia cultures had a normal diploid karyotype,and one had a 6q- deletion which was also present at the time ofdiagnosis.INTRODUCTIONChildhood T-cell acute lymphoblastic leukemias comprisesome 15% of the heterogeneous group of the acute lymphoblastic leukemias (1). At diagnosis the patients often have aperipheral WBC of greater than 108/ml, extensive bone marrowinvolvement (80-90% blasts), and a rapidly dividing populationof relatively immature, monoclonal or oligoclonal T-lympho-blasts. The patients have a poor prognosis and a short survivalunless treated without delay. Even when treated, relapse is acommon occurrence in T-ALL.1Little is known about the mechanism underlying the development of T-ALL. Progress in the cytogenetic characterizationof the disease has been limited, in contrast to the case of the B-cell leukemias and lymphomas where many of the specificchromosomal changes associated with lymphoid malignancieshave been identified. Recurrent chromosomal abnormalitiesinvolving the a or AŸchains of the T-cell receptor or deletionsin the short arm of chromosome 6 are seen in only about one-third of T-ALL cases. However, a surprisingly large percentageof cases (30-50% depending on stage, Ref. 2; or 3 of 4 cases,Ref. 3) show apparently normal karyotype. Acquisition of autocrine growth properties or activation of specific oncogenesmay play a role in the early phases of the disease (3-7).However, difficulties in maintaining cultures of leukemic cellsfrom patients at diagnosis have impeded the study of theinduction of T-ALL.A number of leukemia or lymphomacell lines of T-cell originhave been established from patients in relapse (3,8-13). Successhas, until recently, been limited to patient samples provided atthe time of relapse; even in these cases only a small fraction of