Reproducibility of neutrophil percentages in pooled and non-pooled nasal lavage samples

Results The mean (±SEM) neutrophil percentage was not significantly different between the two methods (80 ±12 for SSL, 86 ±8 for MSL, p=0.2). At a minimum total cell count (TCC) cutoff of ≥20, the neutrophil percentage intraclass correlation (ICC) was similar but not sufficiently reproducible for SSL at 0.588 compared to MSL at 0.641. For samples with TCC≥100, the neutrophil percentage ICC of SSL was 0.93 (excellent correlation) and that of MSL was 0.676 (satisfactory). The evaluable samples for TCC≥100 were 60/84 for SSL and 67/84 for MSL. We previously demonstrated in the same experiment that a minimal TCC cutoff of ≥100 cells gave excellent eosinophil percentage ICC for both methods (>0.8). Conclusion SSL ICC was superior to MSL in measuring nasal lavage neutrophil percentage. This method could be used to assess the effects of inhalant stimuli on the nasal cavity.