Strongyloides ratti infection induces transient nematode-specific Th2 response and reciprocal suppression of IFN-gamma production in mice.

Over one-third of the world population is infected with parasitic helminths, Strongyloides ssp. accounting for approximately 30-100 million infected people. In this study, we employ the experimental system of murine Strongyloides ratti infection to investigate the interaction of this pathogenic nematode with its mammalian host. We provide a comprehensive kinetic description of the immune response to S. ratti infection that was reflected by induction of antigen-specific IgM and IgG1, mast cell activation and a Th2-like cytokine response. T cells derived from infected mice displayed an increased IL-3, IL-4, IL-5, IL-13 and IL-10 response to CD3-engagement in comparison with T cells derived from naïve mice. The IFN-gamma response to CD3-engagement that was well detectable in T cells derived from naïve mice, however, was suppressed in T cells derived from infected mice. Both, the induction of the S. ratti-specific Th2 response and the suppression of pro-inflammatory cytokines were transient and observed in strict correlation to the course of infection and the number of infective larvae used. Finally, comparing artificial infections induced by subcutaneous injection of larvae to natural infections, we observed similar antigen-specific T cell responses although the natural infection led to a significantly lower worm burden.