Methods: Uniform methods for induction (3, 4, 5%, 21 minutes) and processing (plug selection with DTT) were used on normals (N=148), asthmatics (N=97), COPD (N=200), atopics (N=195), otherwise healthy smokers (N=43), atopic smokers (N=45) and ex-smokers (N=47). Endpoints examined included initial raw sample weight, selected plug weight, total and differential cell counts, cell viability, induction success, slide quality score and slide readability.
Results: COPD subjects produced significantly less raw sputum (2667mg) and selected plug material (1320 mg) but yielded significantly (p<0.05) higher total cell counts (4.7x106 cells; 6420 cells/mg) and PMN levels (80%; 5831 pmn/mg) vs all other subject cohorts. Percent PMN levels in normals and asthmatics were equal (28%) but asthmatics had the lowest absolute PMN/mg count (259 PMN/mg) vs all subjects. Interestingly, COPD subjects demonstrated the highest and lowest % Eos (2.2%) and % Lym (0.3%), respectively vs all subjects. Cell viability was lowest among atopics (65%) and highest among COPD (78%). Asthmatics demonstrated the poorest ability to produce sputum (71% success rate) and smokers were the best (95%). Slide quality score and slide readability did not differ significantly among the subject cohorts analyzed.
Conclusions: Baseline sputum parameters differ among healthy and diseased subjects. These differences can inform important decisions regarding subject recruitment, study design and optimal application of sputum.