The Influence of IgE-Enhancing and IgE-Suppressive γδ T Cells Changes with Exposure to Inhaled Ovalbumin

It has been reported that the IgE response to allergens is influenced by gamma delta T cells. Intrigued by a study showing that airway challenge of mice with OVA induces in the spleen the development of gamma delta T cells that suppress the primary IgE response to i.p.-injected OVA-alum, we investigated the gamma delta T cells involved. We found that the induced IgE suppressors are contained within the V gamma 4(+) subset of gamma delta T cells of the spleen, that they express V delta 5 and CD8, and that they depend on IFN-gamma for their function. However, we also found that normal nonchallenged mice harbor IgE-enhancing gamma delta T cells, which are contained within the larger V gamma 1(+) subset of the spleen. In cell transfer experiments, airway challenge of the donors was required to induce the IgE suppressors among the V gamma 4(+) cells. Moreover, this challenge simultaneously turned off the IgE enhancers among the V gamma 1(+) cells. Thus, airway allergen challenge differentially affects two distinct subsets of gamma delta T cells with nonoverlapping functional potentials, and the outcome is IgE suppression. The Journal of Immunology, 2009, 183: 849-855.