Pulmonary Surfactant Protein A Enhances the Host-defense Mechanism of Rat Alveolar Macrophages

作者：Freek van Iwaarden, Berris Welmers, J. Verhoef, Henk P. Haagsman, LAMBERT M. G. VAN GOLDE · 发表于：American Journal of Respiratory Cell and Molecular Biology · 年份：1990 · DOI：10.1165/ajrcmb/2.1.91 · 被引用次数：370 · 研究领域：Neonatal Respiratory Health Research、Immune Response and Inflammation、Antimicrobial Peptides and Activities

Abstract The effects of surfactant, surfactant lipids, and surfactant protein A (SP-A) on the surface phagocytosis of [3H]thymidine-labeled Staphylococcus aureus (SAE) by rat alveolar macrophages were studied. Alveolar macrophages only ingest SAE when the bacteria are opsonized with rat serum prior to incubation with alveolar macrophages. Preincubation or “opsonization” of the bacteria with surfactant did not result in phagocytosis by the macrophages. However, preincubation of the macrophages with surfactant increased the phagocytosis of rat serum-opsonized bacteria by approximately 70% when compared to the control macrophages. The factor present in surfactant causing the stimulation of the phagocytosis is probably SP-A. Preincubation of macrophages with human SP-A enhanced the phagocytosis to the same extent as whole surfactant, whereas preincubation with surfactant lipids had no effect on the phagocytosis. The SP-A-induced enhancement of the phagocytosis is time, temperature, and concentration dependent. Phagocytosis of opsonized SAE by alveolar macrophages was maximal after 15 min of incubation and at an SP-A concentration of 1 µg/ml. No phagocytosis occurred at 0° C. In addition, whole surfactant and SP-A induce a lucigenin-dependent chemiluminescence response in alveolar macrophages. The chemiluminescence response is initiated after 15 min of incubation and reaches a maximum after 30 min. The concentration of SP-A needed for an optimal response is in the same order of ma...