Multiparameter characterization of L3 leukemia cell populations

Multiparameter analysis of 14 consecutive patients with L3 cell populations (FAB classification) in bone marrow showed consistently high mean cellular RNA content but heterogeneity with respect to percent cels in S- and G2M-phases of the cell cycle, cell surface phenotype, cytogenetic abnormalities, cellular DNA content, and nuclear activities of terminal deoxynucleotidyl transferase. Five of the 14 patients had the characteristic profile of L3 leukemia with high RNA content, a typical t(8;14) or t(8;22) translocation, low Tdt, B-cell surface phenotype, pseudodiploid modal number of chromosomes, high proliferation and normal DNA index. The remaining 9 patients had features thought to be unusual and they were very heterogeneous. Median survival time from time of diagnosis was 115 days with no patient alive after 474 days. The survival times exhibited excellent correlation with a parametric model assuming exponential distribution. Accordingly, the presence of abnormal DI predicted for decreased, and the presence of t(8;14) or pseudodiploidy was associated with increased survival rates. However, due to the small number of patients in this study, generally applicable conclusions should be drawn only from a collection of larger numbers of cases of this rare type of leukemia.