Quis Custodiet Ipsos Custodes? Regulation of Cell-Mediated Immune Responses Following Viral Lung Infections

Viral lung infections are leading causes of morbidity and mortality. Effective immune responses to these infections require precise immune regulation to preserve lung function after viral clearance. One component of airway pathophysiology and lung injury associated with acute respiratory virus infection is effector T cells, yet these are the primary cells required for viral clearance. Accordingly, multiple immune mechanisms exist to regulate effector T cells, limiting immunopathology while permitting clearance of infection. Much has been learned in recent years about regulation of T cell function during chronic infection and cancer, and it is now clear that many of these mechanisms also control inflammation in acute lung infection. In this review, we focus on regulatory T cells, inhibitory receptors, and other cells and molecules that regulate cell-mediated immunity in the context of acute respiratory virus infection.