| Objective To induce gastric cancer mouse model using 3-methylcholanthrene (3-MCA) and N-methyl-N-nitrosourea (MNU). To assess the characteristics of the changes in levels of white blood count (WBC), CD3+CD4+CD8+T-cell subsets, and CD4+CD25+regulatory T cell (Treg) of both peripheral blood and splenocytes during week 12 and 20 of the construction of the model.Methods Six week-old male BALB/c mice were utilized to establish gastric cancer model. Glandular stomach of the mice was sutured with 3-MCA-containing silk suture, and subsequent intragastric administration of MNU to induce gastric cancer. On week 12 and 20, peripheral blood and splenocytes were tested for WBC count, and CD3+CD4+CD8+T-cell subsets and Treg were assessed by flow cytometries (FCM) with concurrent collection of mice stomachs for pathologic study. Data were then analyzed statistically for changes in level of WBC, T-cell subsets, and Treg.Results1. On week 12,25% of mice showed partial thickening of the gastric mucosa and chronic inflammation. On week 20,37.5% of mice were successfully induced with gastric carcinoma, while the control groups showed no signs of thickening of the gastric mucosa, chronic inflammation or gastric carcinoma.2. Growths of mice were significantly decreased on week 12 and week 20 when compared with the control group (P<0.05).3. Splenocyte WBC counts signigicantly increased on week 20 (P<0.05).4. Treg percentages in the peripheral blood significantly increased on week 20 (P<0.05). Splenocyte Treg percentages showed significant increased on week 12 and week 20 (P<0.05), while the absolute count of Treg showed significant decreased on week 12 (P<0.05) and significant increased on week 20 (P＜0.05).5. In the splenocyte, CD3+cells significantly increased on week 20 (P<0.05). CD4+cells significantly decreased on week 20 (P＜0.05). CD8+cells significantly decreased on week 20 (P<0.05). CD4+/CD8+ratio significantly increased on week 20 (P<0.05).6. In the absolute counts for splenocyte, CD3+cells significantly increased on week 20 (P<0.05). CD4+cells significantly increased on week 20(P<0.05).Conclusions1. Silk suture with 3-MCA-containing silk suture on to the glandular stomach and subsequent intragastric administration of MNU successfully induce gastric carcinoma in BALB/c mice.2. Long-term exposure to carcinogens can cause lose of weight or slowing of growths amount mice, even when exposure to carcinogens stops, weight or growths are still lower than normal. If Long-term exposure to carcinogen cause tumor growth might also lead to lose of weight.3. Long-term exposure to carcinogens can cause decrease in peripheral WBC amount mice, even when exposure to carcinogens stops peripheral WBC are still lower than normal. In contras, the increase of spleen WBC level might be the result of lymphocyte reactive hyperplasia.4. Treg is important for its role in immune regulation during inflammation, and its crucial suppressing ability during tumor growth. High level of Treg during inflammation prevent autoimmunity self tissue damage, while during tumor formation it inhibited the body to produce effective anti-tumor immune response, which leads to tumor immune escape. 5. On early phase of gastric modle constraction, there were an increased in total number of T-cell and Th cell, and due to the suppression effect of Treg, there was an decreased in Tc cell. Later on when carcinomas were successfully induced, the homeostasis of the immune system was disturbed, and showed an decrease in total number of T-cell and Tc, but because of the effects of chronic inflammation and tumor Th level increased. |
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