Kinetics of intraepithelium and lamina propria lymphocyte responses during Giardia lamblia infection in mice.

The responses of intestinal T-cell subsets and immunoglobulin containing cells were assessed during the course of experimental Giardia lamblia infection in inbred NMRI mice. Quantitation of T-cell subsets in intraepithelium (IEL) and lamina propria (LPL) revealed increased influx of Lyt 2.2+ (suppressor/cytotoxic) T cells and Thy 1.2+ T cells during the establishment (3-5 days post-inoculation) and peak (9-11 days post-inoculation) phases of infection. The influx of these cells reduced as the parasite load declined. In contrast, no significant change was noticed in lamina propria and intraepithelial L3 T4+ (helper/inducer) T cells during the establishment or acute phases. However, these cells increased significantly in the decline phase (17-21 days post-inoculation) of infection. The lamina propria IgA-containing cells significantly declined during the establishment and acute phases of infection, and increased significantly as the parasite load in the jejunum declined. Helper/inducer ratios of 0.4 for IEL and 2.0 for LPL accompanied the decline of G. lamblia trophozoites in the gut. Our data thus suggest that induction of helper/inducer T cells during the decline phase of infection concomitant with an increase in lamina propria IgA-containing cells resulted in elimination of G. lamblia trophozoites from the gut.