Cysteinyl leukotriene receptor antagonist (LTRA) is a widely used medicine for
asthma. Cysteinyl
leukotrienes (cysLTs) are involved in the regulation of dendritic cell (DC) function. However, the effects of LTRA on DC-related antimicrobial immunity against harmful respiratory pathogens remain unknown. The purpose of this study was to examine the effects of LTRA administered in vivo on DC function against representative respiratory pathogens in vitro. Pulmonary DCs were isolated from four groups of mice: control, mite
allergen sensitized (AS), and AS mice treated with the
corticosteroid dexamethasone (Dex) or with the LTRA
pranlukast (Prl). These DCs were incubated with mite
allergen,
lipopolysaccharide (LPS), Aspergillus fumigatus, or respiratory syncytial virus (RSV).
IL-10 and
IL-12 production was then determined. Dex treatment significantly inhibited
lipopolysaccharide (LPS)-induced
IL-10 and
IL-12 production as well as baseline
IL-12 production in AS mice. The Prl did not significantly inhibit LPS-induced
IL-10 and
IL-12 production in AS mice. More importantly, Prl significantly increased
IL-10 and
IL-12 in AS mice after
RSV infection. This study shows that LTRA that is used for
asthma potentially up-regulates antimicrobial immunity through modulation of DC function against some
respiratory infections without immunosuppression.