Oral administration of CT increases the number of antigen-specific CD4⁺ T cells without altering their migration pattern <i>in vivo</i>.

<p>GFP^+/− OT-II lymphocytes (5×10⁶) were adoptively transferred to C57BL/6 recipient mice and one day later the mice were orally immunized with PBS (A, C) or 10 µg CT (B, D). One (A–B) and five days (C–D) after oral immunization, the number of GFP^+/− OT-II cells (identified as GFP⁺CD4⁺) present in the spleen (SPL), mesenteric lymph nodes (MLN), peripheral lymph nodes (PLN), Peyers patches (PP), gut, intraepithelial lymphocyte compartment (IEL) and stomach (STO) was determined by flow cytometry. The lymphocyte preparations from the IEL, STO and PP of mice were pooled to obtain sufficient numbers of cells. Represented are the results from individual mice, as well as the average number of lymphocytes per group (dash, n = 3). Lymphocytes from the PP of mice were pooled (n = 3 each). Results are representative of one out of three independently performed experiments. E–G: GFP^+/− OT-II lymphocytes (5×10⁶) were adoptively transferred to C57BL/6 recipient mice. One day later, recipient mice were orally immunized with either PBS, 10 µg CT, 15 mg OVA or 15 mg OVA with 10 µg CT. Five days after oral immunization, the number of transgenic GFP^+/− OT-II (GFP, Vα2, CD4⁺) cells present in MLN (E), spleen (F) and PP (G) was determined by flow cytometry. E–F: Symbols represent results from individual mice obtained in 2 independently performed experiments, the columns represent the mean of each treatment group. G: symbols represent the results from three independent experiments each performed with PP cells pooled from 3 mice, the column represents the mean of the 3 experiments. *denotes <i>P</i><0.05 (one way ANOVA).