Helper T cell subset induction was examined within a single inbred strain of mouse (B10.D2/n) where individuals varied in their ability to expel the nematode parasite Trichuris muris. In this mouse strain approximately half of infected individuals resist
infection whilst half are unable to expel the parasite and harbour chronic mature adult worm
infections. We here assess various T cell and serological parameters in individual B10.D2/n mice infected with T. muris in relation to the number of parasites harboured. Worm burdens showed very significant negative correlations with five different parameters indicative of the selective expansion within the host of helper T cells of the Th2 subset. Thus, in vitro
IL-5 and
IL-9 production by restimulated mesenteric lymph node cells, total
IgE levels, the early parasite-specific
IgG1 response (all P < 0.01) and intestinal
eosinophilia (P < 0.05), were all significantly negatively correlated with worm burden. In addition, levels of
IL-3 were significantly greater in mice resistant to
infection (P < 0.01). In contrast there was a significant positive correlation between worm burden and parasite-specific
IgG2a levels (P < 0.05),
IgG2a production being under the tight control of the Th1-specific
cytokine IFN-gamma and thus a reliable marker for in vivo Th1 cell activation. The data demonstrates that an individual infected with T. muris is capable of mounting either a protective Th2-type response or an inappropriate Th1-type response.(ABSTRACT TRUNCATED AT 250 WORDS)