A novel technique to explore the functions of bronchial mucosal T cells in chronic obstructive pulmonary disease: application to cytotoxicity and cytokine immunoreactivity

Summary Bronchial mucosal CD8 + cells are implicated in chronic obstructive pulmo- nary disease (COPD) pathogenesis, but there are few data on their functional properties. We have developed a novel technique to outgrow these cells from COPD patients in sufficient numbers to examine effector functions. Endo- bronchial biopsies from 15 COPD smokers and 12 ex-smokers, 11 control smokers and 10 non-smokers were cultured with anti-CD3/interleukin (IL)- 2 IL-15. Outgrown CD3 + T cells were characterized in terms of phenotype (expression of CD4, 8, 25, 28, 69 and 56), cytotoxicity and expression of COPD-related cytokines. Compared with IL-2 alone, additional IL-15 increased the yield and viability of biopsy-derived CD3 + T cells (12-16-day culture without restimulation) without alteration of CD4 + /CD8 + ratios or expression of accessory/activation molecules. Biopsy-derived T cells, princi- pally CD8 + /CD56 + cells, exhibited statistically significantly greater cytotoxic activity in current or ex-smokers with COPD compared with controls (P < 0·01).Elevated percentages of CD8 + T cells expressed interferon (IFN)-g, tumour necrosis factor (TNF)-a and IL-13 (P < 0·01) in current COPD smokers compared with all comparison groups. It is possible to perform functional studies on bronchial mucosal T cells in COPD. We demonstrate increased CD8 + CD56 + T cell cytotoxic activity and expression of remodelling cytokines in smokers who develop COPD.