Figure 7.

Dietary zinc supplementation during chronic alcohol ingestion increases GM-CSF receptor expression and bacterial phagocytosis capacity in alveolar macrophages. Alveolar macrophages were isolated from alcohol-fed rats (solid bars) and from alcohol-fed rats whose diets were supplemented with zinc acetate (10, 100, or 500 mg/L; shaded bars) and then analyzed for GM-CSF receptor expression by flow cytometry as described in Materials and Methods. A and B show mean channel fluorescence for the α binding subunit (GM-CSFRα) and the β signaling subunit (GM-CSFRβ), respectively. In parallel, alveolar macrophages from each isolate were incubated with FITC-labeled inactive Staphylococcus aureus and then analyzed for phagocytic function by flow cytometry as described in Materials and Methods and expressed as the phagocytic index (% positive cells × mean channel fluorescence)/100). Shown in C are the phagocytic indices for each group. The insets are representative merged images of an alveolar macrophage (phase contrast) with ingested FITC-labeled bacteria in the alcohol-fed group and the alcohol-fed group supplemented with 100 mg/L of zinc acetate. For all of the data shown in A–C, each value is the mean ± SEM of four rats in each group. Dietary zinc supplementation had no significant effect (P > 0.05) on phagocytic function of alveolar macrophages from control-fed rats (not shown). *P < 0.05 compared with alcohol diet without zinc supplementation.