The temporal relationship among anti-parasite immune elements expressed during the early phase of infection of the rat with Trichinella spiralis

Immunological parameters were measured during the first 20 days of infection with Trichinella spiralis in the rat. Expulsion of adult worms was complete by day 15 postinfection. Eosinophil and neutrophil numbers rose in the blood of infected rats above preinfection levels on days 3 and 6, respectively, and remained high to day 20 postinfection. Release of cytokines by Trichinella-antigen-stimulated mesenteric lymph node cells was measured, and a significant elevation in interferon (IFN)-gamma release was detected during the early stage of infection. Although initiated later, interleukin (IL)-10 release showed a pattern similar to IFN-gamma. Biphasic release of IL-5 was seen with significant elevation above the preinfection level on day 3 and after day 6 postinfection to the end of the study. IL-4 and IL-2 showed biphasic secretion as well, with the level of IL-4 high in the early and middle part of infection, while the level of IL-2 was detectable only at days 2, 3 and 6 postinfection. Serum anti-parasite IgE rose above preinfection levels after day 6 postinfection. Anti-parasite Ig-positive mesenteric lymph node (MLN) cells were evident by day 3 postinfection for IgM, and day 9 postinfection for IgA and total IgG. The number of Ig-positive MLN cells for all antibody classes returned to preinfection levels by day 20 postinfection. Evaluation of the temporal interactions of the key anti-parasite immune components with which the host engages Trichinella shows a complex interplay between Th1 and Th2 helper subsets.