Determination of a CD4+CD25+ Foxp3+T cells subset in Egyptian Colorectal Cancer Patients

Human tumors including colorectal cancers (CRC) are often infiltrated by immune cells predominantly T lymphocytes especially regulatory T (Treg) cells expressing the forkhead box protein 3 (Foxp3). It has been suggested that CD25+CD4+Foxp3+ regulatory T cells (Tregs) might hamper effective immunosurveillance of emerging cancer cell. The aim of this study was to measure the frequency of total CD4+CD25+ Tregs & CD4+CD25+Foxp3+ subset of Treg cells in peripheral blood of Egyptian CRC patients and their correlation with the tumor stage, histopathology of the tumor and lymph node affection. A total of 31 CRC patients were enrolled in the study. The tumor was categorized using a TNM staging system. Peripheral blood samples were collected within the first 24 h of surgery. The frequency of total CD4+CD25+ Tregs & CD4+CD25+ Foxp3+ subset of Treg cells in peripheral blood mononuclear cells (PBMCs) were measured by flow cytometry and absolute count was determined. High frequency of Tregs was detected in cancer patients with distal margin involvement (44-48 cells/μL) compared with those with free distal margin (5-32 cells/μL). Similarly, higher frequency of Tregs were detected (16-44 cells/μL) in cancers with lymph node involvement compared with cancers without lymph node involvement (5-32 cells/μL). Higher frequency of CD4+CD25+Foxp3+ Tregs were found in mucinous adenocarcinomas than in other histopathological types, although both observations were statistically insignificant. The median value for total absolute lymphocyte count/ μL was 639, out of which CD4+CD25+ subset constituted 35 cells, and about half of this subset were Foxp3+Tregs. In conclusion, CD4+CD25+Foxp3+ Tregs may be a useful marker for predicting invasion, metastasis, and prognosis of colorectal cancer in Egyptian patients.