ABSTRACT
Objective To compare a potential role of dendritic cells (DCs) and macrophages in inducing protective immunity against infection with Schistosoma japonicum. Methods DCs and macrophages were pulsed in vitro with soluble egg antigen (SEA) of S. japonicum. BALB/c mice were injected three times with DCs or macrophages, either antigen-pulsed or not,and challenged with 40 ± 2 cercariae of S. japonicum per mouse. Worms were collected 42 days later by portal perfusion of the mice and egg number of liver was calculated. To evaluate whether protective immunity had been induced by preparations of DCs or macrophages, the worm burden and fertility ( eggs per female per mouse liver) were compared between the groups of mice. The antibody level against SEA was detected by ELISA. Results With respect to mice injected with untreated cells, numbers of worms and eggs per female worms were significantly reduced in the groups of mice having received pulsed DCs (26. 3% and 37.9%, respectively), or pulsed macrophages (22. 0% and 30.7%). Untreated DCs and macrophages induced no significant effects. The antibody level against SEA rose in sera of all groups of mice up to 42 days after the challenge, but most pronounced in those immunized with pulsed DCs, although this was not significantly different from other groups. Conclusion The results suggest that the protective immunity against S. japonicum might be induced by DCs to a higher extent than by macrophages after in vitro pulsing with egg antigen.
ABSTRACT
Objective To study the expression of inducible nitric oxide synthase (iNOS) in livers of mice infected with Schistosoma japonicum. Methods The livers of NMRI mice infected with S. japonicum were collected on day 21, 28, 38, 45 post infection(p.i.), total RNA of livers were extracted and kinetics of the mRNA expression of iNOS were detected by RT-PCR, the protein expression of iNOS was then confirmed by Western blotting and the distribution of iNOS in the infected liver was determined by immunohistochemical methods. Results The mRNA expression of iNOS was not detectable in the uninfected liver, iNOS mRNA expression was detected on day 21 p.i, the expression increased on day 28 p.i and peaked on day 38 p.i, then decreased slightly on day 45 p.i. Western blotting showed an iNOS expression in the livers only on day 38, 45 p.i. IFA test showed that the expression of iNOS was maily distributed in the granuloma of the livers. Conclusion S. japonicum infection can induce the expression of iNOS in a time-dependent manner in the liver of the host,and eggs may be the main factor in inducing the expression.
ABSTRACT
Objective To detect the infection of Schistosoma japonicum in mice with a novel test based on agglutination of hybridoma cells and to study the mechanism of the hybridoma cells agglutination. Methods The procedure was developed with a murine cell line H226 producing a monoclonal antibody specific to schistosome 31/32 kDa antigen and sera collected from mice infected with different numbers (10,30,50) of S. japonicum cercariae in different period. Immunofluorescent test was carried out with the hybridoma cells and schistosome-infected sera. Results The circulating antigen was detected by the test as early as 2 weeks after a heavy infection and all mice showed positive results in the test by 5 weeks after infection. The titers of antigen rose along with the lime post infection, and the tilers of sera from heavy infection were statistically higher than that from the mice receiving a lower number of cercariae. Specific yellowish green fluorescence appeared on the membrane of the hybridoma cells; no signal was detected inside. Conclusion Hybridoma cell agglutination test (HCAT) may become useful to diagnose schistosomiasis.