Induction of the expulsion of Strongyloides ratti and retention of Nippostrongylus brasiliensis in athymic nude mice by repetitive administration of recombinant interleukin-3

A repetitive administration of recombinant interleukin-3 (rIL-3), which can induce the expulsion of Strongyloides ratti in athymic nude mice, did not affect the expulsion of Nippostrongylus brasiliensis. Nude mice infected with N. brasiliensis were injected i.p. with a total of 6.8 x 10(5) U rIL-3 or medium twice a day from Day 5 to Day 11 post-infection. The kinetics of expulsion estimated by egg excretion in faeces up to Day 20 post-infection and adult worm burden on Day 21 was not affected by the IL-3 administration. A similar administration with a higher dose (total 10.6 x 10(5) U) of rIL-3 did not alter the adult worm burden on Day 13. The number of intestinal mucosal mast cells on Day 13 was markedly increased by the treatment, although the number of intestinal goblet cells was comparable between the treated and control mice. When nude mice were infected concurrently with N. brasiliensis and S. ratti and then injected repeatedly with rIL-3 (total 2.2 x 10(5) U) from Day 5 to Day 11, adult worms of S. ratti were expelled from the small intestine by Day 13; however adult worms of N. brasiliensis were retained. Again in the concurrent infection, the number of intestinal mucosal mast cells was significantly increased but that of intestinal goblet cells was not altered by the rIL-3 administration. These results indicate that the expulsion of S. ratti is dependent on IL-3 whereas that of N. brasiliensis is less dependent on IL-3.