Replacement of serum by hemolysate as growth promoter for murine leukemic and normal hemopoietic progenitor cells in culture.

The present study was undertaken to test whether lysates prepared from rat erythrocytes can replace serum as in vitro growth promoters for murine leukemic and normal hemopoietic progenitor cells (CFU-C). Normal bone marrow and three leukemic cell lines (P-1081, L-1210 and P-815) were used in all the experiments. The soft agar technique for cloning hemopoietic cells was used to quantitate cell proliferation. Addition of hemolysate to the agar medium at a final concentration of 4% promoted the growth of a maximal number of leukemic colonies, similar to the number of colonies obtained when 20% serum was added to the soft agar. As for normal CFU-C, addition of 10% hemolysate or 40% horse serum promoted the growth of comparable numbers of colonies. Rat hemolysate can therefore replace horse serum as a growth promoter of leukemic and normal CFU-C present in culture. It was also shown that rat hemolysate cannot substitute for the colony stimulating factor (CSF) needed for the cloning of CFU-C. However, addition of hemolysate, CSF and serum to the soft agar cultures promoted a potentiated rather than an additive growth of CFU-C.