Amino acid conferred protection against melphalan: comparison of amino acids which reduce melphalan toxicity to murine bone marrow precursor cells (CFU-C) and murine L1210 leukemia cells.

The effect of the naturally occuring amino acids upon melphalan (L-phenylalanine mustard, L-PAM) toxicity to a host sensitive tissue, the granulocyte and macrophage precursor cells of murine bone marrow (CFU-C), was investigated. At physiological concentrations the L isomers of leucine and glutamine were found to be the most effective of the naturally occurring amino acids in reducing drug toxicity. Tyrosine, phenylalanine and methionine also protected murine CFU-C from melphalan toxicity although the amount of protection provided by these amino acids at physiological concentrations was less than that provided by leucine and glutamine. Little difference was observed in the pattern of amino acid protection of murine CFU-C and murine L1210 leukemia cells. Murine CFU-C however were more sensitive to melphalan both in the absence and presence of amino acids.