GROWTH-CHARACTERISTICS IN-VITRO OF MYELOID LEUKEMIC-CELLS WITH T(6-9)

We report an analysis of in vitro growth characteristics of leukaemic cells from five patients with t(6;9)(p23;q34). Consistent with other r eports of this abnormality, our patients were comparatively young (med ian age at diagnosis, 29 years), and responded poorly to conventional treatment (median survival from diagnosis, 10 months). During active d isease the CFU-GM growth patterns were characterized by an abundance o f granulocytic aggregates (mostly 20-100 cells in size) whose leukaemi c origin was confirmed by cytogenetic analysis. During remission induc tion, colonies derived from regenerating normal progenitor cells colon ies could be distinguished from those derived from persisting leukaemi c cells on the basis of differences in size, morphology, in situ stain ing characteristics, and karyotype. Remission growth patterns were tho se of a normal bone marrow. Our findings add to a growing recognition that the t(6;9) identifies a subset of leukaemic patients with distinc tive clinical, haematologic, molecular, and in vitro growth characteri stics for whom conventional treatment offers little hope of cure or lo ng survival.