PROTECTION OF MICE PREVIOUSLY INFESTED WITH PLASMODIUM-VINCKEI AGAINST SUBSEQUENT SALMONELLA-ENTERITIDIS INFECTION IS ASSOCIATED WITH NITRIC-OXIDE PRODUCTION CAPACITY

When mice previously cured of a Plasmodium vinckei infection were subs equently infected with Salmonella enteritidis the course of bacterial infection was significantly retarded, showing increased survival durat ion as compared with control infections in naive mice. Moreover, on st imulation with lipopolysaccharide and/or interferon-gamma, spleen cell s from malaria-cured mice showed an increased capacity to produce tumo r necrosis factor, interleukin 6, and reactive nitrogen intermediates as compared with spleen cells from naive mice. However, no significant variation in the capacitiy of spleen cells to release reactive oxygen intermediates was observed between previously malarious and naive mic e. The most significant increases were observed in the capacity for re active nitrogen intermediate production after P. vinckei malaria. Thes e results suggest that the observed protection of mice against salmone llosis in the convalescent phase after malaria may be mediated by nitr ic oxides.