Research On The Effects Of Cyclophosphamide In Mice Thymus Pathology

One hundred sixty five female ICR mice(about six weeks) were choose for this experiment, and randomly divided into 3 groups:the control group,CP group I and CP group II. They were respectively given 0 mg/kg,0.6 mg/kg and 6 mg/kg of cyclophosphamide by intraperitoneal injection and last for 7 days. After finishing the injection, the mice were continiously feed for another 14 days and the whole experiment period was 21 days. The thymus of mice were taken on the 1、4、7、14、21th of the experiment. We observed the pathological morphological changes of thymus through optical microscope, used flow cytometry to detect T lymphocyte subsets, and immunohistochemical method to detect cell cycle and apoptosis rate of mice thymus. The results as follows:There were no obvious damage of pathological morphology on thymus in CP I group and the other detection index also had no significant difference compared with control group. On the 7th day, we found that the thymus shrinkaged and the thymus cortex became thinner, medulla became wider and the medulla cell arranged sparsely. On 4th and 7th day of the experiment, the absolute weight and relative weight of thymus in CP II were significantly or extremely significantly reduced compared with control group. According to the results of T lymphocyte subgroup detection, we found the percentage of CD3+ T lymphocyte increased, while CD3+CD4+、CD3+CD8+ and CD4+CD8+ were decreased on lth day of the experiment. At 4th day, the percentage of CD3+CD4+、CD3+CD8+ and CD4+CD8+T lymphocyte got the same change and rule, that is the percentage of CP II group was much lower than CP I group and control group. At 7th day, the percentage of CD3+CD8+T lymphocyte significantly increased. The results of cell cycle detection showed that the percentage of S phase thymus cells became significantly higher on 7th and 14th day in CP II group, compared with the control group, and on 7th day, the apoptosis rate of thymus cell also significantly elevated.The results show that there is no obvious effect when the dose of CP is 0.6mg/kg. But 6mg/kg CP induce obvious morphological change, the decrease of CD4+CD8+ T lymphocyte, the increase of the S phase thymocytes and the up-regulation of apoptotic thymocytes. The above parameters in 6mg/kg CP group got back to normal level at the 14 dyas after drug withdrawal.