Lectin-induced nitric oxide production

Considering that nitric oxide (NO) may be involved in anti-tumoral and anti -parasite lectin effects, in this report we investigated whether lectin ind uces NO production. Lectins from Canavalia brasiliensis, Dioclea grandiflor a, Pisum arvense (PAA), and concanavalin A induced murine peritoneal cells to produce NO in vitro. PAA induced similar levels to that obtained with li popolysaccharide plus interferon-gamma. NO production by adherent cells was significantly lower than that of unfractionated cells, suggesting a combin ation of lectin stimuli directly on macrophages and via lymphocyte stimulat ion. Ex vivo experiments showed that cells stimulated in vivo could maintai n NO production in vitro without further stimuli. NO synthesis blockage in vivo can significantly increase cell numbers in draining lymph nodes after lectin injection compared to unblocked controls, suggesting an in vivo asso ciation of lectin stimuli and NO production. Taken together these data show that lectins can induce NO production both in vitro and in vivo.