Methods
Forty-eight Sprague-Dawley rats were divided into the control (n = 16) and experimental groups (n = 32) to which 4NQO in drinking water was administered. Flow cytometry was used to analyze the prevalence of Tregs in lymphocytes of peripheral blood and regional lymph nodes during 4NQO-induced rat tongue carcinogenesis. CD4+ CD25+ FoxP3+ cells were expressed as a percentage of the total CD4+ cells.
Results
The frequency of Tregs in peripheral blood from squamous cell carcinoma rats was significantly higher than controls (3.82 ± 0.62 versus 1.40 ± 0.31 %, P < 0.001). The proportion of Tregs was sequentially increased from moderate dysplasia to severe dysplasia and SCC (1.94 ± 0.72, 2.29 ± 0.82, and 3.82 ± 0.62 %, respectively). The frequency of Tregs in regional lymph nodes from squamous cell carcinoma rats was also significantly higher than normal rat mucosa (14.67 ± 3.09 versus 5.53 ± 2.07 %, P < 0.001). The percentage of Tregs was gradually increased in moderate dysplasia, severe dysplasia, and SCC groups (8.93 ± 1.74, 10.15 ± 0.86, 14.67 ± 3.09 %, respectively) as compared to control group (5.53 ± 2.07 %).