Expression of the Lymphocyte Chemokine XCL1 in Lung Tissue of COPD Mice, and Its Relationship to CD4(+)/CD8(+) Ratio and IL-2.

We tested the role of the lymphocyte chemokine XCL1 in a murine model of chronic obstructive pulmonary disease (COPD). COPD was instigated in mice by a 12-week exposure to cigarette smoke. Some COPD animals additionally received intranasal injections of recombinant XCL1. We demonstrated that the expression of CD4(+) T cells diminished, while CD8(+) counts increased in the lungs of COPD mice, and that these changes were further aggravated by exogenous XCL1. The levels of XCL1 negatively correlated with CD4(+)/CD8(+) ratio (r = -0.945, p < 0.05). In addition, the levels of this chemokine negatively correlated with the levels of interleukin-2, the lymphokine that is produced by activated CD4(+). This observation further supported negative association between XCL1 and CD4(+) response in an experimental model of COPD. In conclusion, murine model of COPD is characterized by elevated levels of XCL1, increased counts of CD8(+) T cells and diminished ratio of CD4(+)/CD8(+) cells, and decreased activity of CD4(+) T cells. This indicates that XCL1 is involved in chronic inflammatory processes in COPD and may be an important pharmacological target in this disease.