Hemopoietic stem cells in nude mice transplanted with colony-stimulating-factor-producing tumors.

When pieces of a human pulmonary carcinoma which was producing colony-stimulating factor (CSF) were transplanted into nude mice a marked granulocytosis of 10(6)/mm3 was observed in the nude mice 4 weeks after the transplantation. In order to elucidate the control mechanism of hemopoiesis, we studied the kinetics of the hemopoietic stem cells of these mice. The number of GM-CFC, CFUE, Meg-CFC and CFUS in the whole body increased to 6 times, 8 times, 6 times and 36 times as much respectively as those of the control mice. The increase in the number of these progenitors occurred mainly in the spleen. The sera of these mice contained only CSF. The cycling fraction of GM-CFC and CFUS determined by thymidine suicide technique was increased. From these findings, it could be considered that CSF produced in these mice acted directly or indirectly on CFUS inducing their differentiation into committed stem cells.