CD4 and chronic obstructive pulmonary disease: In this regard, we and others have demonstrated the role and pathogenicity of activated IFN-γ and IL-17-secreting subsets of CD4+ and CD8+ T lymphocytes including Th1, Th17, and Tc1 cells in clinical isolates and in mice with COPD (Lu et al., 2015; You et al., 2015; Shan et al., 2009; Lee et al., 2007; Kheradmand et al., 2023).