Effect of levamisole on granulopoiesis in agar culture.

We studied the effect of levamisole on the proliferation of granulocyte-committed progenitor cells (CFU-c) in the agar system. Media conditioned by pooled human peripheral blood mononuclear cells served as source of colony-stimulating activity (CSA). Levamisole at concentrations ranging from 0.1 to 10.0 micrograms/ml had no detectable stimulatory or inhibitory effect on granulopoiesis in vitro. Levamisole added to culture media neither enhanced nor reduced the release of mononuclear cells of CSA. We conclude that the cases of granulocytopenia, occasionally severe, associated with levamisole therapy are more likely to be due to individual idiosyncrasy or hypersensitivity then to dose-related myelotoxicity.