MHC class I-dependent Vgamma4+ pulmonary T cells regulate alpha beta T cell-independent airway responsiveness.

Mice exposed to aerosolized ovalbumin (OVA) develop increased airway responsiveness when deficient in gammadelta T cells. This finding suggests that gammadelta T cells function as negative regulators. The regulatory influence of gammadelta T cells is evident after OVA-sensitization and -challenge, and after OVA-challenge alone, but not in untreated mice. With aerosolized Abs to target pulmonary T cells, we now demonstrate that negative regulation of airway responsiveness is mediated by a small subpopulation of pulmonary gammadelta T cells. These cells express Vgamma4 and depend in their function on the presence of IFN-gamma and MHC class I. Moreover, their effect can be demonstrated in the absence of alphabeta T cells. This novel type of negative regulation seems to precede the development of the adaptive, antigen-specific allergic response.