FIG. 3.

Oral OVA induces systemic Th1 responses and oral tolerance in transgenic mice. (A to F) Proliferation and IFN-γ secretion by T cells from spleens (A to C) and PLN (D to F) of unfed OT.II mice and mice fed 1 mg of OVA 2 or 10 days earlier. Proliferation data are represented as counts per minute in response to titrating doses of OVA in vitro (A and D) and as SI (B and E) at a representative dose of OVA. The proliferation curves of cells from fed and unfed mice were significantly different for both tissues at both time points (P < 0.04). IFN-γ curves were significantly different for splenic cultures at day 2 (C) (P < 0.04) but not at day 10 and were significantly different for PLN cultures at day 10 (F) (P < 0.02) but not at day 2. A 490, absorbance at 490 nm; NS, not significant. (G to I) Oral tolerance in fed OT.II mice. (G) Proliferation of draining PLN cells of OT.II mice fed 1 mg of OVA (+/+) or PBS (−/+) and immunized s.c. 10 days later with 10 μg of OVA (P < 0.004). The response of PLN cells from unmanipulated OT.II mice (−/−) is also shown. (H) Proliferation data are also shown as SI for a representative dose of OVA. (I) IFN-γ in culture supernatants from replicate cultures (P < 0.03 for fed versus unfed groups). Cultures were set up 7 days after s.c. immunization. Data are representative of those from two experiments.