Table 4.

Correlations between sputum inflammatory cell counts and sputum biomarkers in all subjects

Inflammatory cells	Sputum
	IL-8	IL-6	MMP-9	TNF-α
Absolute number
Total cells	−0.28	−0.27	0.20	−0.10
Neutrophils	−0.34	−0.31	0.22	−0.13
Macrophages	0.56c	0.48b	0.19	0.49b
Cell differentiation
Percentage of neutrophils	−0.69e	−0.63d	0.18	−0.41a
Percentage of macrophages	0.72e	0.64d	−0.12	0.49b

Notes:

^aP<0.05,

^bP<0.01,

^cP<0.005,

^dP<0.0005, and

^eP<0.0001 (correlation between variables, by Spearman’s rank correlation coefficient).

Abbreviations: IL-8, interleukin-8; IL-6, interleukin-6; MMP-9, matrix metalloproteinase-9; TNF-α, tumor necrosis factor-alpha.