The influence of metronidazole and its two main metabolites on murine in vitro lymphocyte transformation.

In a study of the immunomodulating properties of metronidazole and its two main metabolites, metronidazole and 1-(2-hydroxyethyl-2-hydroxymethyl)-5-nitro-imidazole (hydroxy metabolite) were seen to enhance the phytohaemagglutinin-A-stimulated mitogenic transformation of murine lymphocytes. The stimulation was observed at suboptimal phytohaemagglutinin concentrations. The lymphocyte transformation was suppressed by 1-acetic acid-2-methyl-5-metronidazole (acid metabolite). The enhancement by metronidazole and its hydroxy metabolite was observed at concentrations corresponding to human serum levels following a normal dosage of metronidazole. Considering the normal serum concentrations of the three substances, the stimulating effect of the hydroxy metabolite may be at least as important as that of metronidazole itself.