Serum IL-6, TNF, and C-reactive protein levels. For each subject, serum levels of A) IL-6 and B) TNF were quantified by ELISA. C) Serum CRP levels were quantified by high sensitivity nephelometry. Columns represent mean ± SEM. *p = 0.002; **p = 0.0003. Normal non-smokers (white), normal smokers (black), and emphysematous smokers (grey).