Prophylaxis of cyanobacterial and mushroom cyclic peptide toxins

The pathogenicity of virulent cyclic peptide toxins of the cyanobacterium, Microcystis aeruginosa, and the mushroom, Amanita phalloides, was prevented in mice by pretreatment with a variety of chemically unrelated agents including hydrocortisone, shellac, certain diazo and triazine dyes and cyclosporine. A. Despite the diverse nature of the protective agents, a feature commonly associated with protection was the ability to impair hepatic uptake of 51Cr-labeled sheep erythrocytes, a function of hepatic macrophages (Kupffer cells). In addition, several of the protective agents are known to affect other aspects of reticuloendothelial cell function. Therefore it seems likely that the hepatic macrophage is involved in the observed protection, although by what mechanism(s) is unknown. The most remarkable prophylaxis was seen with a single injection of Trypan red, which provided nonimmunologic protection against a lethal dose of a cyanobacterial toxin, cyanoginosin-LR, for periods up to 3 months.