Effects of leukotriene C4 on eotaxin production by human lung fibroblasts

Cysteinyl leukotrienes (CysLTs) play important roles in the pathogenesis of bronchial asthma, and induce not only the increase of mucus secretion and smooth muscle contraction but also eosinophil recruitment into airways. However, mechanism of eosinophil recruitment by CysLTs has not been thoroughly elucidated. In this study, we examined the LTC4 on eotaxin production by human lung fibroblasts. The fibroblasts were cultured with chemical mediators including LTC4 in the absence or presence of IL-4 for up to 48h. At the end of the culture period, eotaxin in the supernatants was measured by ELISA. IL-4 clearly enhanced eotaxin production by fibroblasts. LTC4 alone had no effect on eotaxin production. When fibroblasts were cultured with IL-4 plus LTC4, eotaxin production was significantly enhanced in comparison with IL-4 alone. These results suggest that CysLTs may increase eotaxin production by fibroblasts in the presence of IL-4 and that CysLTs may induce eosinophil recruitment into airways through the effect on eotaxin production by fibroblasts in allergic inflammation.