CD68 and chronic obstructive pulmonary disease: In subjects with COPD only, those subjects with higher sub-CD8+ and CD20+ counts on day 7 postinfection had significantly greater peak breathlessness scores (r = 0.58 and 0.50, P = .017 and .033, respectively, Fig E2, A and B) and sub-CD68+ counts on day 7 correlated positively with peak lower respiratory tract symptom scores recorded between day 9 and 14 (r = 0.58, P = .021, Fig E2, C).