Surfactant protein A exhibits inhibitory effect on eosinophils IL-8 production

Eosinophils are believed to be one of the important sources of cytokines su ch as IL-8 at the site of allergic inflammation. It has been demonstrated t hat pulmonary surfactant protein A (SP-A) plays a potential role in modifyi ng inflammation and the immune function. To verify the regulating effect of SP-A on eosinophil cytokine generation, we studied the effect of SP-A by d etermining of IL-8 production and expression stimulated with sIgA or PMA SP -A purified from surfactant recovered from patients with alveolar proteinos is was added to eosinophils isolated by the negative selection method with immunomagnetic beads, and cultured for 24 h. The concentrations of IL-8 in the cell-free supernatants and cell lysates were then measured by ELISA. We also used a semiquantitative reverse transcriptase-polymerase chain reacti on assay to detect the effect of SP-A on IL-8 mRNA expression. SP-A inhibit ed the secretion of IL-8 in a dose dependent fashion. Suppression of IL-8 p roduction by SP-A was significantly inhibited by SP-A antibody (PE10). SP-A also attenuated expression of IL-8 mRNA in eosinophils. These results indi cate that SP-A might have the potential role to modify allergic inflammatio n by inhibiting IL-8 expression and production from eosinophils. (C) 2000 A cademic Press.