Increased Frequency of Foxp3+ Regulatory T Cells in Mice with Hepatocellular Carcinoma

The CD4+CD25+ regulatory T cell (Treg) is a special kind of T cell subset. Studies have showed that Tregcells are involved in a number of physiological processes and pathologic conditions such as autoimmune diseases,transplantation tolerance and cancer. Tregs with unique capacity for immune inhibition can impair anti-tumourimmunity and help tumor cells to escape from immune surveillance. The aim of our study was to investigatewhether Tregs are involved in hepatocellular carcinoma (HCC). A BABL/C mouse with HCC in situ model wasestablished to evaluate the Treg existence in carcinoma tissues and the changes of Tregs in spleen using flowcytometry and immunohistochemistry methods. Granzyme B expression in carcinoma tissues was analyzedby immunohistochemistry to investigate the tumor local immune status.The proportion of CD4+CD25+/CD4+spleen lymphocytes of tumor bearing mice (18.8%±1.26%) was found to be significantly higher than that innormal mice (9.99%±1.90%) (P<0.01 ). Immunohistochemistry of spleen tissue also confirmed that there wasan increase in Treg in tumor-bearing mice, while in carcinomas it showed Treg cells to be present in tumorinfiltrating lymphocyte areas while Granzyme B was rarely observed. Anti-tumour immunity was suppressed,and this might be associated with the increase of Tregs. Our observations suggest that the CD4+CD25+Treg/CD4+ proportion in spleen lymphocytes can be a sensitive index to evaluate the change of Tregs in hepatocellularcarcinoma mice and the Treg may be a promising therapeutic target for cancer.