RAPID EXPULSION OF THE INTESTINAL TREMATODES ECHINOSTOMA-TRIVOLVIS AND ECHINOSTOMA-CAPRONI FROM C3H HEN MICE AFTER INFECTION WITH NIPPOSTRONGYLUS-BRASILIENSIS/

The number of goblet cells in the small intestines of C3H/HeN mice inc reased rapidly following their infection with about 500 third-stage la rvae (L(3)) of the intestinal nematode Nippostrongylus brasiliensis. T he number of goblet cells reached its peak on day 9 postinfection (p.i .). Worm burdens in the hosts' small intestines were determined follow ing a challenge infection with encysted metacercariae of the intestina l trematodes Echinostoma trivolvis or E. caproni on days 8 and 16 afte r primary infections with N. brasiliensis. All metacercariae of E. tri volvis or E. caproni used to challenge the hosts on day 8 p.i. were ex pelled. Considerable numbers of E. trivolvis (48.6%) and E. caproni (6 7.1%) remained in the intestines of hosts challenged with these echino stomes on day 16 p.i. All the controls used for E. trivolvis and E. ca proni infections without primary infections with N. brasiliensis showe d recovery rates greater than 70%. An enzyme-linked immunosorbent assa y (ELISA) showed that the IgM titer rose remarkably and plateaued on d ay 11 p.i. No marked rise in the IgG or IgA titer occurred during the experiment. These results indicate that mucins increased by hyperplast ic goblet cells associated with primary infections with N. brasiliensi s are responsible for a rapid expulsion of the worms of the challenge infection with E. trivolvis or E. caproni from the mouse host.