Normal values for bronchoalveolar lavage (BAL) differential cell count and lymphocyte subpopulations

Abstract

Bronchoalveolar lavage (BAL) cytology is frequently used in diagnostic work-up but normal values for differential cell count derive only from small cohorts. We analysed lymphocyte differentiation from BAL of 83 healthy individuals to establish normal values. Female and male (w:m=1:1,1), smokers and non-smokers (s:ns=1:3) in the age of 15-74 years were analysed. The role of smoking, age, gender, recovery and BAL volume was tested for correlation with BAL differential cell count and lymphocyte immunophenotyping employing CD3, CD4, CD8, and the CD4/CD8-ratio. Immunophenotyping for CD57, CD1a, CD25 and CD20 was available for 34 individuals. In the herein analyzed healthy cohort, immunophenotyping identified 55% of CD3+ lymphocytes as CD4+ (IQR 44,5-68,5), 29% as CD8+ (IQR 19.3-39.0%) and a CD4/CD8 ratio of 1.9 (IQR 1.2-3.3). 1% of cells were CD20+ (IQR 0-2), 9% were CD57+ (IQR 4-13) and 3% CD25 positive (IQR 2-5). CD1a was 1% (IQR 0-1). Smokers tend to have a lower CD4/CD8 ratio (Median=1,9, IQR 1,1-2,3) than non-smokers (Median=2, IQR 1,2-3,9, p=0,36). Age and gender did not influence immunophenotyping in our cohort, however we observed a higher CD4/CD8 obtained by BAL with higher volume (Median=2,95 IQR:1,9-4,8 for lavage volume >300 ml, Median=1,6, IQR:1,1-2,2 for lavage volume <=300 ml, p=0,0009). In summary, we provide normal values for differential cell count in one of the largest cohorts of healthy individuals. Smoking status and lavage volume may influence normal values. The next step is the investigation of their clinical usefulness.