Persistence of Lung CD8 T Cell Oligoclonal Expansions upon Smoking Cessation in a Mouse Model of Cigarette Smoke-Induced Emphysema

The role of adaptive immunity in the development or progression of chronic obstructive pulmonary disease (COPD) remains undefined. Recently, the presence of autoantibodies and autoreactive T cells has been demonstrated in COPD patients. In addition, oligoclonal expansions of lung T cells have been observed in COPD patients, but the overlapping incidence of infections, tumors, and cigarette smoke exposure obscures the antigenic stimulus. We analyzed the TCR V beta repertoire of CD4 and CD8 T cells purified from the lungs and spleens of mice chronically exposed to cigarette smoke. In a mouse model of COPD, we demonstrate that chronic cigarette smoke exposure causes oligoclonal expansions of T cells isolated from the lungs, but not spleens. TCR V beta repertoire analyses revealed oligoclonal expansions predominantly occurred in lung CD8 T cells, with preferential usage of V beta 7, V beta 9, V beta 13, and V beta 14. Using nucleotide sequence analysis based on J beta analyses, we demonstrate selection of CDR3 amino acid motifs, which strongly suggests Ag-driven oligoclonal T cell expansion. Analysis of the lung TCR V beta repertoire of mice with cigarette smoke-induced emphysema, which had undergone smoking cessation for 6 mo, revealed that oligoclonal expansions persisted. This study formally demonstrates that chronic cigarette smoke exposure, alone, causes a persistent adaptive T cell immune response. These findings have important implications for therapeutic approaches in the treatment of COPD, and provide insight into potential mechanisms involved in disease pathogenesis. The Journal of Immunology, 2008, 181: 8036-8043.