Background: T lymphocytes are important components of the bronchial inflamm
atory cell infiltrate in asthma, Because lymphocytes activated in the respi
ratory tract recirculate to remote glandular and mucosal sites, we previous
ly studied the histologic features of minor salivary glands (MSGs) in bronc
hial asthma and found an airway-like inflammation with T-lymphocyte infiltr
ation, the presence of mast cells that were often degranulated, and basemen
t membrane thickening but no eosinophil infiltration.
Objective: We sought to investigate the cellular infiltration and cytokine
profile in MSGs from untreated asthmatic subjects, steroid-treated asthmati
c subjects, and control subjects and to compare these values with those fou
nd in bronchial biopsy specimens.
Methods: The cellular infiltration was studied by using immunohistochemistr
y. Cytokine messenger (m)RNA expression for IL-4, IL-5, and IFN-gamma was d
etermined by using in situ hybridization and cytokine immunoreactivity with
immunohistochemistry.
Results: A significant increase in CD4 and IL-4 mRNA(+) cells was observed
in MSGs from asthmatic patients (both untreated and steroid-treated subject
s) when compared with control subjects, which correlated with the clinical
severity of asthma (FEV1 and Aas score). In contrast to the bronchi, no IL-
5 mRNA expression was observed in MSGs, and no difference was observed for
MSG IFN-gamma mRNA between the groups. At the level of MSG protein expressi
on, the 3 cytokines were seen, with a significant increase in IL-4 protein
expression in steroid-treated asthmatic subjects compared with untreated as
thmatic subjects and control subjects, but there were no differences betwee
n the groups in IL-5 and IFN-gamma protein expression.
Conclusion: The cytokine mRNA expression pattern observed in the MSGs of as
thmatic subjects was different from that found in the bronchi, suggesting a
different local immune regulation.