In vitro effects of lithium on granulocyte colony formation in normal men, in hematological disorders and in small-cell carcinoma of the lung.

In a two-layer soft agar system the indirect effect of lithium via colony stimulating factor and/or its direct effect on the granulocyte progenitor cells of bone marrow of healthy volunteers, patients with different hematological disorders, and with small-cell carcinoma of the lung, were evaluated. A significant increase in the number of myeloid colonies was found with a concentration of 0.1 mmol/l lithium carbonate in the feeder layer in all patient groups except those with overt acute myelomonocytic leukemia (AMMoL). No effect was seen if lithium was added to the overlayer. The increment of colonies cultured with lithium in the feeder layer was directly related to the initial number of colonies cultured without lithium (correlation coefficient 0.96). The former colonies had a 1.5- to 2-times larger size than the latter, and cell cycle analysis showed a significant increase in the percentage of cells in S, G2 and M phase. No such effects were seen in AMMoL on the number and size of the colonies and the characteristic growth pattern. In this study lithium has an indirect effect on the number and size of bone marrow myeloid colony formation in healthy people as well as patients with different hematologic cell disorders and small-cell carcinoma of the lung, while no such influence was observed with overt AMMoL patients.