Leucovorin protection on pluripotent hemopoietic stem cells in mice treated with high-dose methotrexate

Haematologic effects of delayed 16 h administration of leucovorin (LV) following high-dose methotrexate (HDMTX) were analyzed in C57Bl X C3H F1 mice. Results show that 16 h administration of LV significantly reduces the toxic effects of HDMTX on hemopoietic progenitors and bone marrow cells. At 12 days after HDMTX administration, the bone marrow level of CFUs was significantly higher in HDMTX-LV treated mice than in HDMTX treated animals. In comparison with previous data obtained when LV was injected 2 h after HDMTX, the delay in administration of LV does not appear to reduce the protective effect of the vitamin.