Short report: total serum levels of the nitric oxide derivatives nitrite/nitrate during microfilarial clearance in human filarial disease.

Nitric oxide (NO) has recently been shown to be cytotoxic to both microfilariae and adult Brugia malayi in vitro and in a murine model, as well against Onchocerca lienalis microfilariae in vitro. We studied the kinetics of nitrite/nitrate, both stable end products of NO, by high-pressure liquid chromatography during microfilaricidal chemotherapy in four filariasis (three Loa loa, and one Onchocerca volvulus) patients. High serum levels of nitrite/nitrate were released during microfilarial clearance and sustained elevated levels were observed six months after chemotherapy, suggesting a role of NO in the elimination of microfilariae in human filariasis.