CD8A and influenza: Previous studies have shown that heterosubtypic immunity (i.e., cross-protective across multiple influenza A strains) induced in the mucosal tissue of the respiratory tract by influenza infection is mediated by CD8 cytotoxic T lymphocyte (CTL) responses [64] and by broadly non-neutralizing antibodies (bNA) through antibody-dependent phagocytosis by alveolar macrophages [65].