Biological immunomodulators are routinely evaluated as a natural source of molecules with profound effects on the immune system. They belong to a group of physiologically active compounds, collectively termed biological response modifiers. Most of the studies were focused on immune system stimulation. Recently, they have become the focus of studies seeking molecules that are able to overcome negative effects of various immunotoxins. This paper concentrates on the effects of a glucan/resveratrol/vitamin C combination on immunosuppressive effects of mercury and perfluorinated hydrocarbons. Effects described in this review have strong clinical potential, as environmental contaminants have adverse effects on all aspects of the immune system and represent a serious threat to the health of both humans and animals.