The percentages of circulating CD28+CD8+ T cells were significantly lower in patients with asbestosis and silicosis than in the healthy controls (P < 0.05) (Fig. 5b), and the percentages of circulating HLA-DR+CD8+ T cells were significantly higher in both groups than in the healthy controls (P < 0.05) (Fig. 5d). This evidence concerns the gene CD28 and asbestosis.