Correlation of bronchoalveolar lavage lymphocyte count with the extent of lung fibrosis and with plethysmographic lung volumes in patients with newly recognized hypersensitivity pneumonitis

Introduction
Hypersensitivity pneumonitis (HP) is an increasingly recognized interstitial lung disease, presenting with elevated total cell counts and high percentage of lymphocytes in bronchoalveolar lavage fluid (BALF). Despite many publications, there is no consensus in the literature concerning BALF cellular composition in patients with prolonged course of HP.

Aim
The aim of the present retrospective study was to investigate the influence of disease duration, smoking habits, and the extent of lung fibrosis on BALF cells’ population in patients with newly recognized HP.

Material and methods
In total, 94 patients (49 females, 45 males), mean age 52 (±12) years, with HP recognized according to recently proposed criteria, were enrolled into the present study. Chest CT scans were retrospectively reviewed by two independent radiologists. BALF evaluation was performed as a part of routine diagnostics according to recent recommendations.

Results
Percentage of lymphocytes in BALF was significantly lower in patients with lung fibrosis (stage 1 and 2) comparing to those without lung fibrosis (stage 0). Significant correlation was also found between the percentage of BALF lymphocytes and plethysmographic lung volumes, but not with lung transfer capacity for carbon monoxide (TLCO% pred). Smoking did not influence BALF results in our study group.

Conclusions
BALF lymphocytosis correlated with the presence and the extent of lung fibrosis on chest CT as well as with plethysmographic lung volumes but did not with TLCO and smoking habits in newly recognized HP pneumonitis.