Schistosoma mansoni antigens modulate the activity of the innate immune response and prevent onset of type 1 diabetes.

Infection with Schistosoma mansoni (S. mansoni) or exposure to eggs from this helminth inhibits the development of type 1 diabetes in NOD mice. In this study we show that soluble extracts of S. mansoni worm or egg completely prevent onset of type 1 diabetes in these mice but only if injection is started at 4 weeks of age. T cells from diabetes-protected mice make IL-10 in recall responses to parasite antigens. These cells are furthermore impaired in their ability to transfer diabetes to NOD-SCID recipients. Bone marrow dendritic cells derived from NOD mice are found to make more IL-10 and less IL-12 following culture with S. mansoni soluble egg antigens in conjunction with lipopolysaccharides. NOD mice are deficient in NKT cells. Soluble worm and egg antigens increase the numbers of V alpha 14i NKT cells in NOD mice. These effects of schistosome antigens on the innate immune system provide a mechanism for their ability to prevent type 1 diabetes in NOD mice.