γδ T cells regulate mucosally induced tolerance in a dose-dependent fashion

Abstract

We used gammadelta TCR-deficient (TCRdelta(-/-)) mice to examine the role of gammadelta T cells for induction of mucosal responses and systemic tolerance to high versus low doses of oral antigen. When either TCRdelta(-/-) or TCRdelta(+/+) mice were immunized orally with a high dose of ovalbumin (OVA) prior to parenteral challenge, systemic IgG and IgE antibody responses were markedly reduced in both types of mice, while mucosal IgA responses were reduced only in the TCRdelta(-/-) mice. Reduced T cell proliferative responses and delayed-type hypersensitivity were seen in TCRdelta(-/-) and TCRdelta(+/+) mice given the high dose of OVA. Antigen-induced T(h)1 and T(h)2 cytokine production by splenic CD4(+) T cells was severely inhibited in orally tolerized TCRdelta(-/-) and TCRdelta(+/+) mice. In contrast, while oral tolerance associated with increased levels of IL-10 synthesis was induced by a low dose of OVA in TCRdelta(+/+) mice, the TCRdelta(-/-) mice were not tolerized and failed to produce IL-10. Our findings indicate that gammadelta T cells play a significant immunoregulatory role in IL-10-mediated, low-dose oral tolerance induction, but are not essential participants in the induction of systemic tolerance to orally introduced antigens given in larger doses.

Peyer's patches are required for oral tolerance to proteins

“…Briefly, PBS (20 l) containing 10 g of OVA was injected into the left ear pinna of the mice, whereas the right ear pinna received PBS as control (30,31). In studies of TNP-specific responses, 0.8% of TNCB solution (20 l) was painted on the left ear pinna.…”

“…The spleen was removed aseptically and single-cell suspensions were prepared in RPMI 1640 medium (Cellgro Mediatech, Washington, DC) containing Hepes buffer, nonessential amino acids, sodium pyruvate, L-glutamine, penicillin, streptomycin, and gentamycin (incomplete medium; refs. 27,30,31,33). CD4 ϩ T cells were purified by the magnetic activated cell sorter system (Miltenyi Biotec, Auburn, CA) as described (27,(30)(31)(32).…”

“…27,30,31,33). CD4 ϩ T cells were purified by the magnetic activated cell sorter system (Miltenyi Biotec, Auburn, CA) as described (27,(30)(31)(32). Cells were passed through the magnetized column after incubation with biotin-labeled anti-CD4 mAb (GK 1.5) and streptavidin-conjugated microbeads.…”

“…To establish systemic unresponsiveness to a high dose of oral protein, a standard protocol was used as described (30,31). Mice were intubated gastrically with 25 mg of hen egg white OVA (Sigma) dissolved in 0.25 ml of PBS.…”

“…Seven days later, mice were immunized via the s.c. route with 100 g of OVA in 100 l of complete Freund's adjuvant (CFA) (OVA͞CFA; Difco). OVA-specific T and B cell responses were determined 14 days after s.c. immunization (30,31). In other experiments, mice were fed 0.25 ml of PBS or PBS containing 10 mg of the hapten TNBS (Research Organics) on days 0 and 7 to induce hapten-specific systemic unresponsiveness (32).…”