ABSTRACT
Free radicals, molecules with one or more unpaired electrons, are used by the phagocytic cells of the immune system to aid in the killing of pathogens and tumor cells. Free radicals initiate the liberation of arachidonic acid from phospholipids from cellular membranes. Products of the arachidonic acid cascade are synthesized during free radical chain reactions. Antioxidants have the capacity of lowering the free radical burden either by interfering with the initiation of free radical formation or by inactivating the radicals once they are formed. The critical importance of vitamin A in lowering the morbidity of viral infections, such as measles, has been recently linked to the requirement of macrophages for cell-mediated responses to this and other potentially pathogenic microbes. Research in this area is encouraged, since the antioxidant vitamins have been shown to be safe at levels well beyond 10 times the recommended daily allowance.
