Lead and catechol hematotoxicity in vitro using human and murine hematopoietic progenitor cells

In vitro cloning assays for hematopoietic myeloid and erythroid precursor cells have been used as screening systems to investigate the hematotoxic potential of environmental chemicals in humans and mice. Granulocyte-monocyte progenitors (CFU-GM) from human umbilical cord blood and from mouse bone marrow (Balb/c and B6C3F1) were cultured in the presence of lead and the benzene metabolite catechol. Erythroid precursors (BFU-E) from human umbilical cord blood were cultured in the presence of lead. The in vitro exposure of the human and murine cells resulted in a dose-dependent depression of the colony numbers. The concentration–effect relationship was studied. Results showed that: (1) Based on calculated IC50 values, human progenitors are more sensitive to lead and catechol than are murine progenitors. The dose that caused a 50% decrease in colony formation after catechol exposure was 6 times higher for murine cells (IC50 = 24 μmol/L) than for human cord blood cells (IC50 = 4 μmol/L). Lead was 10–15 times more toxic to human hematopoietic cells (IC50 = 61 μmol/L) than to murine bone marrow cells from both mice strains tested (Balb/c, IC50 = 1060 μmol/L; B6C3F1, IC50 = 536 μmol/L). (2) A lineage specificity was observed after exposure to lead. Human erythroid progenitors (hBFU-E) (IC50 = 3.31 μmol/L) were found to be 20 times more sensitive to the inhibitory effect of lead than were myeloid precursors (hCFU-GM) (IC50 = 63.58 μmol/L). (3) Individual differences in the susceptibility to the harmful effect of lead were seen among cord blood samples. (4) Toxicity of lead to progenitor cells occurred at environmentally relevant concentrations. This revised version was published online in July 2006 with corrections to the Cover Date.