Influence of Humoral Regulators on Proliferation and Maturation of Normal and Leukemic Cells¹

Factors that influence the proliferation of marrow elements can be detected in sera. To determine the function and to compare the effect of these factors, cells were obtained from patients with normal and leukemic bone marrows. The effects of drug-induced stimulatory and inhibitory sera and leukemic pretreatment sera over time (0 to 6 days) on proliferation and granulocytic morphology of normal and leukemic bone marrow cells in culture were evaluated. Increased proliferation was associated with stimulatory sera, while inhibitory and leukemic pretreatment sera retarded proliferation of both normal and malignant cells. Exposure of normal proliferative cells to inhibitory or leukemic pretreatment sera yielded the greatest increase in mature granulocyte forms. In contrast, although the proliferative response of leukemic cells to these sera was similar to normal, maturation was minimal. These data suggest that leukemic pretreatment sera are similar to inhibitory sera and are not leukemogenic. Both retard proliferation of normal and leukemic bone marrow cells while enhancing maturation of normal cells. Leukemic myeloblasts, however, cannot be made to mature by these humoral regulators.