The frequency of lung NK cells, but not lung CD56+ T cells, co-expressing CD8 correlates with FEV₁ % predicted.

<p>(<b>A–C</b>) NK cells; (<b>D–F</b>) CD56+ T cells. (<b>A</b>) Representative staining for CD8 on CD56+ CD3− NK cells from a smoker without COPD (left panel) and a COPD subject (right panel); blue line, CD8+ staining; grey line, isotype control. (<b>B</b>) Subjects were categorized by pulmonary function (x-axis) versus the percentage of NK cells that co-express CD8 (y-axis); x, smokers without COPD (<i>n</i> = 5); □, mild COPD (<i>n</i> = 9); Δ, severe COPD (<i>n</i> = 9); Kruskal-Wallis one-way ANOVA testing was used to determine significance. (<b>C</b>) The percentage of NK cells that co-express CD8 (y-axis) versus FEV₁ % predicted (x-axis). Spearman correlation was used to determine the p-value. (<b>D</b>) Representative staining for CD8 and CD4 on CD56+ CD3+ T cells from a smoker without COPD (left panel) and a COPD subject (right panel). The numbers in the quadrants are the % of each subset among all lung CD56+ T cells. (<b>E</b>) CD4 single-positive (brown bars), CD8 single-positive (orange bars), and CD8/CD4 double-negative (grey bars) are shown as the percentage of lung CD56+ T cells for individual subjects. No difference was seen between groups. (<b>F</b>) The percentage of lung CD56+ T cells (y-axis) that express CD4 (brown symbols) or CD8 (orange symbols) versus FEV₁ % predicted (x-axis); x, smokers without COPD (<i>n</i> = 5); □, mild COPD (<i>n</i> = 9); Δ, severe COPD (<i>n</i> = 9).