The role of γδ T cells in the airways

Based on their T cell receptor expression two distinct T cell populations have been identified and designated as alpha beta and gamma delta T cells. While the specific role of alpha beta T cells is well understood, the specific function of gamma delta T cells remains elusive. Despite the limited knowledge on what gamma delta T cells exactly recognize as their antigen or antigens, several studies have clearly demonstrated that gamma delta T cells are important regulators of immune responses. Studies on gamma delta T cells in the lung have shown that gamma delta T cells influence B and T cell responses. For instance, gamma delta T cells modulate CD4(+)alpha beta T cells in tuberculosis, and in allergic inflammation they support IgE production. Furthermore, a recent study on their role as part of the innate immune response has demonstrated that gamma delta T cells regulate airway function independently of alpha beta T cells. This novel finding provides an opportunity to review previous studies on gamma delta T cells in the lung of mice and humans. The examination of these data demonstrates that understanding the role of the various subsets of gamma delta T cells will be critical in elucidating their function as "immunosurveillance cells" of the lung.