Free radical generation during primary infections with Nippostrongylus brasiliensis

The production of free radicals during infection of the rat with Nippostrongylus brasiliensis was investigated. Lipid peroxidation, which is the best documented effect of free radicals, was monitored in the small intestines of infected rats by measurement of malonyldialdehyde and was found to be increased at the time of worm rejection. The capacity of peritoneal leucocytes to produce free radicals, as measured by chemiluminescence, was monitored in rats infected with different doses of N. brasiliensis. Rejection of N. brasiliensis from rats infected with 6000 third-stage larvae (L3) began 2 days earlier than in rats infected with only 600 L3. Maximal free radical generation also occurred 2 days earlier and was quantitatively greater in rats infected with 6000 L3. Free radical generation by leucocytes in response to live adult N. brasiliensis was enhanced by plasma from infected rats indicating the existence of a plasma-borne factor responsible for the initiation of free radical generation in response to N. brasiliensis.