The immunomodulation effects of minoxidil were investigated using various parameters. Minoxidil did not cause any modulation of in vitro antibody response to lipopolysaccaride(LPS), DNP-Ficoll and sheep red blood cell (SBRC). But minoxidil increased mitogen, LPS and concanavalin A (Con A), - induced lymphoproliferation at relatively low concentration and did not have any increase of phytohemagglutinin (PHA)-induced proliferative response.
Meanwhile the coculture with rat hepatocytes was used to elucidate immunomodulation of metabolites minoxidil which could be produced by hepatocytes. In coculture system, minoxidil enhanced T-dependent antibody response to SRBC by dose-dependence but lost enhancing effect in in vitro mitogen - induced lymphoproliferative assay. In addition, in vivo exposure of minoxidil to mice did not caused any immunomodulation effects which were presented in vitro coculture system.
These results suggest that metabolites of minoxidil have immunomodulation on T-cell specific response and minoxidil itself affect mitogen - induced proliferative response although mechanism of immunomodulation is not well-known.
