MAST-CELL AND HISTAMINE INVOLVEMENT IN FARMERS LUNG-DISEASE

The aim of this study was to evaluate the cellular and biochemical cha racteristics of the bronchoalveolar lavage (BAL fluid in patients with farmer's lung disease (FLD). Total cell numbers in BAL fluids from pa tients with FLD (n=30) were significantly higher than in normal subjec ts (n=7; p<0.01), and differential cell counts were significantly diff erent. Lymphocytes were the most numerous cell type in BAL fluids from patients with FLD (65.4 +/- 2.5 percent vs 6.8 +/- 0.5 percent), and analysis of lymphocyte subsets revealed increased percentages of CD3() and CD8(+) cells (91.8 +/- 0.9 percent vs 68.8 +/- 3 percent, p<0.01 , and 54.3 +/- 3.1 percent vs 30.1 +/- 3.2 percent, p<0.01, respective ly). A marked increase in mast cell numbers, as revealed by the specif ic alcian blue/safranin staining, was observed in patients with FLD (4 .2 +/- 0.57 percent, n=12, vs 0.18 +/- 0.04 percent, n=7, p<0.001). Hi stamine levels in BAL supernatants were increased in patients with FLD (mean=SEM, 4.4 +/- 0.8 ng/ml vs 0.9 +/- 0.1 ng/ml; median, 2.4 ng/ml vs 0.9 ng/ml, p<0.01), and correlated positively with mast cell number s and percentages (r =+0.63, p<0.03, and r=+0.69, p<0.02, respectively ); conversely, a negative correlation was found between histamine leve ls and CD8(+) lymphocyte percentages.(r= -0.48, p<0.01). Raised neutro phil percentages (5.1 +/- 0.8 vs 0.5 +/- 0.18, p<0.05) and albumin con centrations (29.2 +/- 3.9 mg/dl vs 3.4 +/- 1.3 mg/dl, p<0.01) were als o found in patients with FLD. These findings show that increased numbe rs of mast cells, lymphocytes, and neutrophils can be found in BAL flu ids of patients with FLD. The increased histamine levels in the supern atants of BAL fluids indicate that mast cells are activated. These dat a allow us to postulate a role for mast cell accumulation and histamin e release in the inflammatory process of FLD.