THE EFFECT OF ENDOTOXIN ON IN-VIVO RAT ALVEOLAR MACROPHAGE PHAGOCYTOSIS

This study was performed to explore whether alveolar macrophage (AM) p hagocytosis would be impaired during endotoxemia. Therefore, we charac terized in vivo AM phagocytic function in rats following either intrav enous (IV) or intratracheal (IT) administration of lipopolysaccharide (LPS). The IV administration of LPS to rats at dosages of 0, 1, 2, and 5 mg/kg showed that increasing LPS doses were significantly associate d with ino eased AM phagocytosis of Au-198 colloid (P < .01), decrease d recovery of AMs in bronchoalveolar lavage (BAL) (P = .017), no signi ficant differences in neutrophil recovery by lavage (P = .15), or in t he concentration of albumin in BAL (P = .14). Across the dosages of LP S administered IT (i.e., 0, 1, 5, and 10 mg/kg), there was no differen ce in AM phagocytosis (P = .29), a significant decrease in AM recovery (P = .002), a significant increase in neutrophil number (P = .01), an d little effect on the concentration of albumin (P = .06). Thus, we fo und that the administration of endotoxin to mis did not impair in vivo AM phagocytic function. In fact, our findings suggest that the IV adm inistration of LPS mar increase AM phagocytosis of Au-198.