IMMUNOLOGICAL RELATIONSHIPS DURING PRIMARY INFECTION WITH HELIGMOSOMOIDES-POLYGYRUS (NEMATOSPIROIDES-DUBIUS) - DOWN-REGULATION OF SPECIFIC CYTOKINE SECRETION (IL-9 AND IL-10) CORRELATES WITH POOR MASTOCYTOSIS AND CHRONIC SURVIVAL OF ADULT WORMS

Mice were infected either with Trichinella spiralis (day 0), Heligmoso moides polygyrus (day - 14) or concurrently with both species and were killed in groups, together with naive control mice, on 2 occasions (d ay 8 and 15 post infection with T. spiralis, corresponding to days 22 and 29 p.i. with H. polygyrus). The expulsion of T. spiralis was slowe d significantly in concurrently infected mice and this was associated with a reduced mastocytosis and lower serum mucosal mast cell protease levels. Mesenteric lymph node (MLN) lymphocytes from all three experi mental groups secreted IL-3 and IL-4 in copious amounts when stimulate d in vitro by Concanavalin A (Con-A), but the secretion of high levels of IL-9 and IL-10 was essentially confined to mice infected with T. s piralis alone. It is suggested that adult H. polygyrus selectively mod ulate cytokine secretion by Th2 cells within the MLN during infection and that this is brought about as a direct consequence of the mechanis m employed by H. polygyrus to depress mucosal inflammatory responses i n order to facilitate its own survival.