Figure 4.

Determination of nitric oxide (NO) production in culture supernatants. Peritoneal exudate cells (PEC) from 1-month-infected mice were left unstimulated (–) or were stimulated in vitro with lipopolysaccharide (LPS) or parasite VF- and Em2(G11)-antigen. White bars refer to non-infected control mice, black bars to wild-type (WT) mice and striped bars to inducible nitric oxide synthase-knockout (iNOS-KO) mice. Each point was measured in quadruplicate. Supernatants were harvested after 24, 48 and 72 hr (LPS) or 96 hr (VF-antigen and Em2(G11)-antigen), respectively; nitrite (NO₂⁻) accumulation was assessed using the Griess method. This is one representative out of four independent experiments with similar patterns of NO production.