Expulsion of Nippostrongylus brasiliensis from the intestine of rats. Collaboration between humoral and cellular components of the immune response.

The role played by immune lymph node cells in expulsion of normal, damaged and adapted adult worms (Ogilvie and Hockley, 1968) from the small intestine of the rat was studied. Sensitized mesenteric lymph node cells caused the rapid and complete expulsion of worms which had previously been damaged by the action of antibodies. Over the same time, about 50 per cent of normal worms were expelled from cell recipients, and there was a ten-fold reduction in egg production by these worms. Adapted worms were markedly less susceptible than normal worms to the immunological attack mounted by the transferred cells. These results confirm and extend those of Jones and Ogilvie (1971) and Keller and Keist (1972) and show that worm expulsion occurs in two steps (1) antibody action followed by (2) cellular action and that cells are not effective until step (1) has occurred. It seems that worm expulsion is caused by a rate limiting factor which is triggered by interaction of antigen with sensitized lymphocytes. These results are related to previous studies of immunity to this and other nematodes.