Low‐level infection with Trichuris muris significantly affects the polarization of the CD4 response

Abstract

Resistance and susceptibility to the intestinal nematode Trichuris muris has been shown to be dependent upon the induction of T helper type 2 (T_h2) or T_h1 cells, respectively. This study demonstrates that in a normally resistant strain of mouse, i.e. BALB/K which mounts a dominant T_h2 response, sub‐threshold levels of infection (< 40 eggs) can survive and become sexually mature adult worms (10–20 adults). The immunological basis of this phenomenon was found to be a dramatically altered polarization of the CD4 response. The T_h2‐response characteristic of this strain of mouse infected with T. muris was shown to be significantly down‐regulated as assessed by in vitro cytokine production [interleukin (IL)‐4, IL‐5 and IL‐9]. In contrast, T_h1 parameters of infection such as in vitro interferon‐γ production and the presence of parasite‐specific IgG2a were greatly up‐regulated in these mice.