G Grilli

Cytogenetic evidence for a clonal selection of leukemic-cells in culture

Abstract Cytogenetic analysis of bone marrow leukemic cells of 33 patients was performed in direct preparation and in short term liquid culture. In eight patients a clonal selection of abnormal clones was observed in the short term liquid culture. This finding is consistent with the hypothesis that leukemic cells with the most pronounced chromosomal abnormality have a growth advantage compared to the more “normal” cells.

VARIATIONS IN ERYTHROID AND MYELOID PROGENITOR CELL NUMBERS IN NORMAL HUMAN PERIPHERAL BLOOD

Barrett et al(1979) have recently reported on the variability of blood CFU-c concentrations in healthy donors. Blood samples were taken once every week for 10 weeks and a 3-4 week cyclical change in CFU-c/l was found. Kreutzmann & Fliedner (1979) found in the peripheral blood of three healthy individuals in whom blood was taken three times a week for 10 weeks, systematic fluctuations with periods of 19.5, 22.7 and 25.3 d. Early erythroid precursors (BFU-e) have also been found in the peripheral blood by several authors (Ogawa et al, 1977; Clarke & Housman, 1977), but serial studies have not been performed. We wish to report on studies that were performed to characterize the normal variations in both the blood BFU-e and CFU-c concentrations, and to establish correlations between the two populations. Venous blood from three healthy individuals was collected in a heparinized syringe at 08.0O-09.00 hours on every second day for 36 d. After Ficoll-Isopaque separation loh mononuclear cells (MNC) were plated in 3.5 cm plastic Petri dishes in 1 ml Iscove’s modified Dulbecco’s medium (GIBCO) and containing 0.8% methylcellulose, 30% fetal calf serum (FCS), 1 % deionized and delipidated bovine serum albumin, 360 p g human transferrin saturated with iron, M alphathyoglycerol and 1 U anaemic sheep plasma erythropoietin (Connaught) or 0.07 ml ofhuman placenta conditioned medium (HPCM) 4-fold concentrated prepared by the method of Schlunk & Schleyer (1979). In order to eliminate any loss of activity, FCS, erythropoietin and HPCM were frozen in small amounts so that only the required amount was thawed for every experiment. Duplicate cultures of CFU-c were counted after 10 d and of BFU-e after 14 d of incubation in fully humidified air with 4% CO2. The average levels of BFU-e and of CFU-c/ml blood are shown in Table I. BFU-e values were higher than CFU-c values during the whole experiment. The BFU-e/CFU-c ratio expresses the average number of BFU-e that we have found for 1 CFU-c in every donor. BFU-e and CFU-c average numbers of donor 2 were significantly different from those of donors 1 and 3 ( P <0.001). CFU-c average number was also significantly different between donors 1 and 3 ( P ~0.001). The BFU-e/CFU-c ratio ofdonor 1 was significantly different from that of donors 2 and 3 ( P cO-001). The fluctuations of BFU-e and CFU-c/ml blood in the three donors are shown in Fig 1. The degree of correlation between BFU-e and CFU-c fluctuations in every individual is weakly significant (P c0.05 in donors 1 and 3, and P <0.01 in donor 2). The results of this study suggest that BFU-e and CFU-c are regular elements in the population of blood mononuclear cells. The average BFU-e and CFU-c blood concentrations appear to be characteristic of the single individual as well as the ratio between BFU-e and CFU-c. However, systematic cyclical oscillations of the CFU-c and BFU-e blood concentrations could not be detected since this study was too short to confirm the findings mentioned above. Although no relationship was found between the blood monocyte concentration and the frequency of erythropoietic or granulocytopoietic colonies, it is not possible to exclude that