Mast cells, eosinophils and antibody-mediated cellular cytotoxicity are not critical in resistance to Trichuris muris

The murine intestinal nematode Trichuris muris provides an invaluable model of human infection with T, trichiura, Hence, analysis of the immunological responses in the mouse may elucidate the mechanisms of immunity to trichur iasis in man. The work described here investigates the roles of eosinophils , mast cells and antibody-dependent cell-mediated cytotoxicity (ADCC) in th e elimination of T. muris from the host gut. Following ablation of IL-5, an d hence eosinophilia, mice usually resistant to T. muris infection remained so. Further, blocking the stem cell factor receptor, c-kit, to facilitate complete ablation of mast cells over the period of parasite expulsion in re sistant mice had no effect on the development of protective immunity. There fore it can be deduced that eosinophils and mast cells are not critical in resistance. In addition to these studies, the role of antibody-mediated cel lular cytotoxic mechanisms was investigated via the analysis of an infectio n time course in Fc gamma R-/- mice. These animals, on a resistant backgrou nd, were fully immune and expelled the parasites before development of the adult stage. Thus this model provides evidence against a major role for ADC C in resistance to infection with T. muris, The studies described here have eliminated some of the major effector mechanisms traditionally associated with helminth infection, and work continues to elucidate the critical immun e responses associated with resistance.