IL-4, IL-10 and IFNγ production in TGFβ1-null mice fed low doses of OVA

Previous studies by others have indicated that feeding low doses of antigen induces active suppression, mediated by the release of inhibitory cytokines, particularly TGFβ1. However, we have recently shown that low dose oral tolerance can be generated in the absence of TGFβ1 using TGFβ1 null mutant mice. In the present study, the level of IL-4, IL-10 and IFNγ was examined in cell supernatants of TGFβ1 null mutant mice fed low doses of OVA. Neonates identified as either control (+/+ or +/-) or TGFβ1-null (-/-) mice were given injections of anti-CD11α (anti-LFA-1) every other day from day 2 after birth until weaning. Anti-CD11α has previously been shown to extend the life of TGFβ1-null mice. Mice were then gavaged with either water or 1 mg of OVA for three days. Eight days after the last feeding, all mice were immunized in the tail base and footpad with OVA in IFA. Eleven days later, mice were sacrificed and lymphocytes from the spleen and popliteal lymph nodes were incubated in vitro for 48 hours with either OVA or medium alone; supernatants from each group of mice were then harvested, pooled and stored at -70°C. Levels of IL-4, IL-10 and IFNγ, were determined using antigen capture ELISA. Results indicated that in all TGFβ1-null mice fed OVA, concentrations of IL-4, IL-10 and IFNγ were decreased compared to water fed controls. Similar results were found for wild-type control mice. These results imply that Th2 as well as Th1 cells are tolerized in mice fed low doses of OVA.