Additionally, proliferation of helper T (CD3+ CD4+) and cytotoxic T (CD3+ CD8+) cells exposed to 10 μg/ml Ludox or NM-200 was significantly higher in silicosis patients than in controls, although SI values >2.5 were only observed in CD3+ CD8+ cells when exposed to 10 μg/ml Ludox (Table 3). This evidence concerns the gene CD4 and silicosis.