Studies on the involvement of prostaglandins and their precursors in the rejection of Nippostrongylus brasiliensis from the rat

In vitro incubation of 6-day Nippo-strongylus brasiliensis in the presence of PGE₁ at 1000 ng/ml and PGE₂ at 500–10,000 ng/ml of medium did not affect worm motility nor in vivo survival of worms implanted into the small intestine of recipient rats. The intraduodenal injection of 250 and 500 μg PGE₁ or PGE₂ did not lead to expulsion of worms from infected rats. An in vitro exposure to precursor fatty acids of PGE₁ and PGE₂, dihomo-γ-linolenic acid and arachidonic acid, respectively, at concentrations of 1000–15,000 ng/ml of medium also failed to inhibit worm motility and in vivo worm survival. These results are at variance with some earlier reports and do not suggest that prostaglandins are directly involved in the immune rejection of N. brasiliensis. No prostaglandins could be demonstrated in worm homogenates.