Comparative studies on the levels of serum IgG1 and IgG2a in susceptible B10.BR mice infected with different strains of the intestinal nematode parasite Trichuris muris.

Comparative studies were carried out on the levels of serum IgG1 and IgG2a in susceptible B10.BR mice infected with different strains of Trichuris muris (E-J and S strains). As infection proceeded, levels of IgG1 and IgG2a increased in mice infected with either strain until at least day 32 post-infection (p.i.). There were no differences in the IgG1 levels on days 14, 20, and 25 p.i. between mice infected with either E-J or S strain, whereas IgG2a levels on days 20, 25, and 32 p.i. were higher in S-infected mice than those in E-J-infected mice. Isotype switching to IgG2a is entirely dependent on interferon gamma (IFN-gamma) and, according to our previous results, the period of high IFN-gamma production in S-infected B10.BR mice is long compared to E-J-infected B10.BR mice. Thus, increased levels of IFN-gamma may sustain high levels of serum IgG2a in S-infected mice. Taken together, levels of serum IgG2a are useful markers of IFN-gamma production in T. muris infection.