Competitive survival/proliferation of normal and Ph1-positive haemopoietic cells.

Bone marrow (BM) cells from 10 patients with Ph1-positive chronic granulocytic leukaemia (CGL) were placed in long-term cultures in the presence of fetal calf serum (FCS) and horse serum (HoS), or in the presence of human AB serum. The long-term cultures were started with three different cell combinations: (1) CGL BM cells (four cases), (2) CGL BM cells + normal BM cells (1:1 ratio) from an HLA identical sex-matched sibling (five cases), (3) CGL BM cells + normal BM cells (1:1 ratio) from an HLA identical sex mismatched sibling (five cases). Cytogenetic studies were performed at weeks 0, 3, 4 and 5 of culture. The results of this study can be summarized as follows: (a) Ph1-positive cells could be detected at any time of culture in all three of the described cell combinations; (b) a population of Ph1-negative cells of patient origin could be detected after 3-5 weeks of culture; (c) there was a trend for a better survival of Ph1-negative cells in cultures supplemented with FCS + HoS and, conversely, of Ph1-positive cells in cultures containing human serum. These results warrant further studies on the possibility of manipulating survival and proliferation of normal and leukaemic cells by varying the culture conditions.