Korean J Parasitol.  2012 Mar;50(1):29-35. 10.3347/kjp.2012.50.1.29.

T Regulatory Cell Responses to Immunization with a Soluble Egg Antigen in Schistosoma mansoni-Infected Mice

Affiliations
  • 1Department of Immunology, Theodor Bilharz Research Institute, Imbaba, Giza, Egypt.
  • 2Department of Parasitology, Theodor Bilharz Research Institute, Imbaba, Giza, Egypt. ibrahimshalash@yahoo.com
  • 3Department of Hematology, Theodor Bilharz Research Institute, Imbaba, Giza, Egypt.
  • 4Department of Biology, American University in Cairo, Cairo, Egypt.

Abstract

The aim of the study is to characterize the phenotypes of CD4+ CD25+ T regulatory cells within the liver granulomas and association with both Foxp-3 gene expression and splenic cytokines. Naive C57BL/6 mice were intravenously injected with multiple doses of the soluble egg antigen (SEA) 7 days before cercarial infection. The immunized and infected control groups were sacrificed 8 and 16 weeks post-infection (PI). Histopathology, parasitological parameters, splenic phenotypes for T regulatory cells, the FOXP-3 expression in hepatic granuloma using real-time PCR, and the associated splenic cytokines were studied. Histopathological examination of the liver revealed remarkable increase in degenerated ova within hepatic granuloma which decreased in diameter at weeks 8 and 16 PI (P<0.01). The percentage of T regulatory cells (CD4+ CD25+) increased significantly (P<0.01) in the immunized group compared to the infected control at weeks 8 and 16 PI. The FOXP-3 expression in hepatic granulomas increased from 10 at week 8 to 30 fold at week 16 PI in the infected control group. However, its expression in the immunized group showed an increase from 30 at week 8 to 70 fold at week 16 PI. The splenic cytokine levels of pro-inflammatory cytokines, IFN-gamma, IL-4, and TNF-alpha, showed significant decreases (P<0.05) compared to the infected control group. In conclusion, the magnitude and phenotype of the egg-induced effects on T helper responses were found to be controlled by a parallel response within the T regulatory population which provides protection in worm parasite-induced immunopathology.

Keyword

Schistosoma mansoni; T regulatory cell; soluble egg antigen; Foxp-3 gene
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