PARASITOLOGICAL, HISTOPATHOLOGICAL AND IMMUNOLOGICAL CHANGES IN NON-IMMUNIZED, IMMUNIZED AND IMMUNOSUPPRESSED MICE EXPERIMENTALLY INFECTED WITH T. SPIRALIS
MAHMOUD A. EL-SHAFEY*, HANY A. AFIFY AND ASHRAF S. METWALLY.
Departments of Clinical Pathology* and Parasitology, Faculty of Medicine, Zagazig university, Zagazig, Sharkia Governorate, Egypt.
Objective: The aim of the present study was to evaluate the parasitological, histopathological and immunological changes that occurr in non-immunized, immunized and immunosuppressed Swiss albino mice experimentally infected with T. spiralis.Methodology:Three hundreds Swiss albino mice were divided into four groups :The first group (50 mice) was the normal healthy control.The second group (50 mice) was immunized with T. spiralis larval antigen (100 g/intraperitoneal injection mouse with equal volume of complete Freund's adjuvant) for 3 times with 2 weeks intervals, then one week after the last dose, all immunized mice were infected orally with 250-300 T. spiralis larvae/mouse.The third group (50 mice) was normal non-immunized mice infected orally with 250-300 T. spiralis larvae/mouse.The fourth group (150 mice) was infected with 250-300 T. spiralis larvae/mouse then subdivided into three subgroups to be immunosuppressed by Kenacort (subgroup A), endoxan (subgroup B) and cyclosporine (subgroup C).Five mice from each group and subgroup were sacrificed weekly starting from one week after infection to the 10th week post infection for :Collection and counting of adult worms in the intestine of the infected mice.Counting of larvae in muscle samples (after peptic digestion) of eviscerated carcasses of infected mice (starting from the 5th to 10th week post infection).Intestinal & skeletal muscle specimens were prepared for histopathological study.Collection of blood samples to be tested immunologically by ELISA technique for the presence of specific IgG antibodies.Results:At the end of the 1st week post infection, the mean number of adult worms detected in the small intestine of immunized infected mice was lower when compared with non-immunized infected mice.In addition; the mean number of intestinal adult worms showed gradual reduction till the end of the 10th week post infection regarding subgroups A & B ; while that of subgroup C was gradually reduced till complete expulsion of adult worms by the end of the 4th week post infection.Histopathological examination revealed marked reduction in both intestinal inflammatory infiltrates & muscular encystation of larvae in mice immunosuppressed with cyclosporine when compared with those immunocompromized with endoxan & kenacort.Lastly by using ELISA; specific IgG antibodies could be detected one week post infection in sera of all infected mice.Conclusion:Immunization with T. spiralis larval antigen gave highly significant induction of humoral & cellular immune responses that led to rapid expulsion of adult worms and reduction of larval burden. On the other hand; usage of immunosuppressive agents compromised the immunopathological response to the parasite.