Nitric oxide production by chicken macrophages activated by acemannan, a complex carbohydrate extracted from Aloe Vera

Cultures of normal chicken spleen cells and HD11 line cells produce nitric oxide (NO) in response to Acemannan, a complex carbohydrate derived from the Aloe vera plant. Neither cell type produced detectable amounts of NO in response to similar concentrations of yeast mannan, another complex carbohydrate. Nitric oxide production was dose dependent and inhibitable by the nitric oxide synthase inhibitor N^G-methyl-l-arginine. In addition, the production of NO was inhibited by preincubation of ACM with concanavalin A in a dose-dependent manner. These results suggest that ACM-induced NO synthesis may be mediated through macrophage mannose receptors, and macrophage activation may be accouantable for some of the immunomodulatory effects of ACM in chickens.