Objective To investigate changes and significance of CD4+CD25+Foxp3+ regulatory T cells (Treg cells) in peripheral blood of silica exposed rats at different stages, and to explore the role that Treg may play in the development of silicosis.
Methods Forty healthy male SD rats were randomly divided into the model and the control groups, with 24 rats in model group and 16 rats in control group. One miniliter silica suspension (40 mg/mL)was administrated via intratracheal instillation while equal amount of saline was instilled to the rats of control group. Animals were sacrificed on the 7th, 14th, 21st and 28th day after instillation. The levels of CD4+CD25+ T cells and Treg cells were analyzed by flow cytometry.
Results During the stage of acute alveolitis (on the 7th day), the levels of CD4+CD25+ T cells and Treg cells in silicotic rats were significantly lower than those in control group (P<0.05). During the development stage of silicotic granuloma (on the 14th day), the levels of CD4+CD25+ T cells and Treg cells in silicotic rats increased slightly and approached to those of control group. On the 21st day, the levels of both CD4+CD25+ T cells and Treg cells were higher than those in control group, but without statistical significance. During the stage of more silicotic granuloma and fibrosis (on the 28th day), both of the levels significantly increased with statistical significance (P<0.05).
Conclusion Treg cells may play an important role in the maintenance of immune tolerance and the development of silicosis.
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