Phagocytic and Bactericidal Activities of Pulmonary Macrophages following Sublethal Traumatic Shock 1

Summary

The in vitrophagocytic and bactericidal responses of rat alveolar macrophages were investigated following sublethal traumatic shock. Phagocytosis of relabeled Pseudomonas aeruginosa by lung macrophages was elevated 1 hr post-trauma in the absence of bacterial opsonins. This response was transient with a return to normal by 24 hr. Bacterial phagocytosis by control and trauma alveolar macrophages was doubled in the presence of serum obtained either prior to or following trauma. In association with this acute phagocytic activation, resting 0₂consumption as well as bactericidal activity was stimulated in isolated alveolar macrophages harvested at 60 min post-traumatic injury. In contrast, the recoverable yields of lung macrophages following traumatic injury were significantly reduced at both the 1-hr and 24-hr postinjury period. Alveolar macrophage phagocytosis and metabolism are thus rapidly and transiently activated following host defense mechanisms following sublethal trauma. This response is in direct contrast to the previously documented acute depression of the hepatic Kupffer cell following traumatic shock and may represent a compensatory response of the lung RES during periods of hepatic RES dysfunction.