Detection of nitrosylated epitopes in Trypanosoma brucei gambiense by polyclonal and monoclonal anti-conjugated-NO-cysteine antibodies

Activated macrophages with the Calmette/Guerin bacillus (BCG) have a cytoto xic/cytostatic effect on the extracellular parasite, Trypanosoma brucei gam biense. This effect was inhibited when the NO-synthase inhibitor NG-monomet hyl-L-arginine (NMMA; 0.5 mM) was added to the culture media. Using an immu nocytochemical method with rabbit polyclonal or mouse monoclonal antibodies directed against conjugated nitroso-epitopes (anti-conjugated-NO cysteine) , nitrosylated antigens were visualized in fixed trypanosomes. These result s suggest that NO was synthesized by the activated macrophages and that it reacted with some parasitic proteins containing cysteine. The release of NO bound to parasitic proteins may cause the killing of trypanosomes. The imm unoreactivity was positive when the trypanosomes were obtained from the sup ernatant of the BCG-activated macrophages that contains BSA (4 mg/mL). In c ontrast, the parasites cocultured with non-activated macrophages remained c ompletely viable, and, the immunoreactivity was completely negative. ((C) A cademie des sciences / Elsevier, Paris.)