Study objectives: BAL induces alveolar inflammation,
but its effects on intrapulmonary cytokines and the mechanisms causing
inflammation are uncertain. The objectives of this study were: (1) to
characterize cytokine response in the lungs to BAL, and (2) to
determine whether endotoxin is introduced into the lungs during BAL,
which could promote BAL-induced inflammation.
methods: We performed two BAL procedures in healthy volunteers
separated by 4 (n = 6), 24 (n = 5), or 72 h (n = 3). The
initial BAL was performed in the right middle lobe (RML) and the second
BAL was performed in the same location and the lingula. Concentrations
of interleukin-8 (IL-8), interleukin-1β (IL-1β), and transforming
growth factor-β were measured by enzyme-linked immunosorbent assay
and tumor necrosis factor-α (TNF-α) bioactivity was determined.
Endotoxin contents of saline (10 and 20 mL) infused through
bronchoscopes as well as BAL fluids recovered from six subjects were
assessed by limulus amebocyte assay.
4 h after the initial lavage, but not at later times, BAL fluid
recovered from the RML contained increased concentrations of IL-8 and
IL-1β, and increased TNF-α bioactivity. BAL fluid recovered from
the lingula contained increased concentrations of TNF-α only at
4 h. All BAL samples tested contained detectable endotoxin as did
all saline aliquots instilled through bronchoscopes.
Conclusions: There is intrapulmonary accumulation of the
cytokines TNF-α, IL-8, and IL-1β in the lavaged lung within 4
h after BAL; this accumulation resolves by 24 h. Endotoxin
contamination of the lungs during bronchoscopy may contribute to
BAL-induced lung inflammation.
Abbreviations: EU = endotoxin unit;
IL-1β = interleukin-1β; IL-8 = interleukin-8; RML = right
middle lobe; TGF-β = transforming growth factor-β;
TNF-α = tumor necrosis factor-α