Poorer NF-kB signaling by microfilariae in macrophages from BALB/c mice affects their ability to produce cytotoxic levels of nitric oxide to kill microfilariae

Abstract

Upon activation with microfilariae (mf), macrophages from C57Bl/6 mice showed higher nuclear factor-kB (NF-kB) but lower activating protein 1 DNA-binding activity as compared to BALB/c macrophages. The C57Bl/6 macrophages produced cytotoxic levels of nitric oxide (NO) to kill Setaria cervi mf as compared to BALB/c macrophages. Inhibition of the NF-kB signal by pyrrolidine dithiocarbamate (PDTC) blocked NO production and microfilaricidal activity of C57Bl/6 macrophages and inclusion of the exogenous NO generator (SNP) in the PDTC treated C57Bl/6 macrophage cultures induced mf cytotoxicity. These results underscore that the NF-kB signal (induced in response to mf) is important for the NO-mediated microfilaricidal activity of macrophages.