The role of gammadelta T cells in the airways.

Based on their T cell receptor expression two distinct T cell populations have been identified and designated as alphabeta and gammadelta T cells. While the specific role of alphabeta T cells is well understood, the specific function of gammabeta T cells remains elusive. Despite the limited knowledge on what gammadelta T cells exactly recognize as their antigen or antigens, several studies have clearly demonstrated that gammadelta T cells are important regulators of immune responses. Studies on gammadelta T cells in the lung have shown that gammadelta T cells influence B and T cell responses. For instance, gammadelta T cells modulate CD4+alphabeta 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 gammadelta T cells regulate airway function independently of alphabeta T cells. This novel finding provides an opportunity to review previous studies on gammadelta T cells in the lung of mice and humans. The examination of these data demonstrates that understanding the role of the various subsets of gammadelta T cells will be critical in elucidating their function as "immunosurveillance cells" of the lung.