To assess whether mast cell and eosinophil (EOS) degranulation occurs in the airway of subjects with moderately symptomatic
asthma, we have measured levels of preformed mast cell-derived mediators (
histamine and
tryptase) and EOS-derived mediators (major basic
protein and EOS-derived
neurotoxin) in bronchoalveolar lavage fluid (BALF) obtained from patients with symptomatic (N = 14) and asymptomatic
asthma (N = 9) and patients without
asthma (N = 6). Both the FEV1 (1.52 +/- 0.33 L:55% +/- 15% of predicted FEV1) and the forced expiratory flow at 50% (FEF50) (1.11 +/- 0.62 L/sec:26% +/- 14% of predicted FEF50) in the patients with symptomatic
asthma were significantly lower than the corresponding values for FEV1 (3.16 +/- 0.45
L:86% +/- 10% of predicted FEV1) and the FEF50 (4.04 +/- 1.54 L/sec:71% +/- 25% of predicted FEF50) in the patients with asymptomatic
asthma. Levels of
histamine (4.8 +/- 5.0 ng/ml versus 0.2 +/- 0.2 ng/ml) (p = 0.05), EOS-derived
neurotoxin (420.6 +/- 959.4 ng/ml versus 12.6 +/- 7.7 ng/ml) (p = 0.05), major basic
protein (31.4 +/- 46.6 ng/ml versus less than 9 ng/ml) (p = 0.05), and percent EOSs (10.6% +/- 7.0% versus 1.1% +/- 0.9% of BAL cells) (p = 0.0006) were all significantly elevated in BALF from symptomatic compared to asymptomatic patients with
asthma. The elevated levels of
tryptase (13.2 +/- 14.8 ng/ml versus 3.9 +/- 3.9 ng/ml) in BALF from symptomatic compared to asymptomatic patients with
asthma approximated, but did not reach, statistical significance. Spontaneous histamine release from BAL mast cells of symptomatic patients with
asthma was 46% +/- 5% compared to 5% +/- 2% in asymptomatic patients with
asthma. In response to antihuman
IgE, histamine release from BAL mast cells recovered from asymptomatic patients with
asthma increased to 25% +/- 10%, whereas in BAL mast cells of symptomatic patients with
asthma, no
anti-IgE potentiation of histamine release occurred. This study suggests that mast cell and EOS degranulation is ongoing in the airway of patients with moderately symptomatic
asthma.