PROPHYLACTIC AND THERAPEUTIC IMMUNE RECONSTITUTION OF SCID MICE INFECTED WITH ENCEPHALITOZOON-CUNICULI

Severe combined immunodeficient (SCID) mice develop lethal infections, resembling opportunistic microsporidioses of immunocompromised patien ts, after intraperitoneal (i.p.) inoculations of spores of Encephalito zoon cuniculi. In the present study, SCID mice reconstituted i.p. with 5x10(7) spleen cells from naive adult BALB/c mice 14 days prior to th e i.p. injection of 10(7) spores were completely resistant to the infe ction, whereas control infected SCID mice developed clinical disease a nd died within 17 days post infection (DPI). In another experiment, SC ID mice infected i.p. with 10(7) spores of E cuniculi and after that ( on DPI 7) injected i.p. with 5x10(7) spleen lymphocytes isolated from immune adult BALB/c mice were partially protected against the parasite (40% of the reconstituted mice survived). In both experiments, high l evels of parasite-specific serum antibodies (mostly of the IgG-isotype ) were detected in the infected immunocompetent BALB/c mice, whereas v irtually no antibodies were found in the infected SCID mice. However, SCID mice reconstituted with either naive spleen cells or immune lymph ocytes revealed humoral immune responses comparable with those of immu nocompetent mice.