HIV-1 transgene expression decreases metallothionein expression and zinc levels in alveolar macrophages and these changes can be rapidly reversed with dietary zinc supplementation. Shown are the percentage of alveolar macrophages that were positive for MT1 (left three columns) and for zinc (right three columns) by flow cytometry performed on macrophages isolated from wild type rats (WT), from HIV-1 transgenic rats (HIV-1) and from HIV-1 transgenic rats whose drinking water was supplemented with 100 mg/L of zinc acetate (HIV-1 + zinc). HIV-1 transgenic rats have significantly decreased MT1 expression and intracellular levels of zinc in their alveolar macrophages. Each value represents the mean ± SEM of 4 determinations. *p < 0.05 decreased compared to untreated wild type rats. **p < 0.05 increased compared to untreated HIV-1 transgenic rats.