Cytogenetic and in vitro culture studies on chronic myelomonocytic leukemia.

Six cases of chronic myelomonocytic leukemia were studied with cytogenetic and colony-formation techniques. Chromosome studies on bone marrow cells with the Q-banding method revealed cytogenetic changes in three of the six patients; +5, +8, +21, -13, -X, +1q, and 7q-. Chromosome changes among cases showed no particular correlation with survival or with the tendency to develop the acute phase. In vitro culture studies in the three cases showed that most of the hematopoietic precursors in the patients were considered to be myelomonocytic cells, with a variable number of colonies. Adherent cells from the patient's marrow had inhibitory effects for colony formation; on the other hand, patient serum showed elevated colony-stimulating activity.