| The IgE response of infected rats and its relationship to protection against Trichinella spiralis infection is the focus of the research in this work. The results demonstrate that T. spiralis infection stimulates a strong IgE response in the intestine. Analysis of IgE turnover showed that over 99% of the total IgE produced at 10 days post-infection (dpi) entered the intestinal lumen, indicating that the intestine is capable of mounting an IgE response which is largely secretory.; The parasite specific IgE response appears earlier and is stronger in the intestine than it is in serum. Furthermore, at 14 dpi, 60% of total intestinal IgE but only 10% of total serum IgE could be absorbed by T. spiralis muscle larvae and adult antigens. The kinetics of the specific intestinal IgE response are similar to the intestinal IgA response, the classical secretory immunoglobulin of the intestine.; IgE immunoprecipitated from the intestinal wash of 14 day infected rats reacted with a series of high molecular weight proteins (90-200 kDa) present in T. spiralis adult metabolic antigens (adult ESA) that are unreactive with 14-day serum IgE. The appearance of adult ESA specific IgE in the intestine of different strains of rats coincides with the ability of each strain to eliminate the adult worm from the intestine. For example, Lewis rats, a strain capable of eliminating the intestinal parasite before 14 dpi, showed strong intestinal IgE reactivity against adult ESA at 12 dpi, while PVG rats, which eliminate the parasite later, show the same reaction against adult ESA only after 14 dpi.; Evidence that strengthened the case for a direct role of IgE in adult worm rejection was derived from an in vitro assay that quantified worm invasion in monolayers of a cell line (IEC-G) derived from gut epithelium of rats. When bound to IL-4 stimulated IEC-G cells, intestinal IgE, but not serum IgE, prevented invasion by adult worms.; Additional studies in Nippostrongylus brasiliensis and Heligmosomoides polygyrus infected rats showed that the total level of IgE increased in the intestinal lumen during H. polygyrus infection, but not during N. brasiliensis infection, therefore an intestinal IgE response is not a general phenomenon in gastrointestinal parasite infection. |
