Evaluation of cytolytic activity and phenotypic changes of circulating blood immune cells in patients with colorectal cancer by a simple preparation of peripheral blood mononuclear cells

PURPOSE This study aimed to assess the cytolytic activity and the phenotype of circulating blood immune cells in cancer patients by using a simple preparation of peripheral blood mononuclear cells (PBMCs). METHODS Peripheral blood was obtained from 94 diagnosed colorectal cancer (CRC) patients and 112 healthy donors. PBMCs were cocultured with K562 cells for 2 hours and lactate dehydrogenase released from the dead K562 cells was measured by using a spectrophotometer. Meanwhile, PBMCs were stained with fluorescence conjugated monoclonal antibodies (mAbs) and analyzed by flow cytometry. RESULTS The cytolytic activity of PBMCs were significantly different between CRC patient and healthy groups (8.82% ± 3.84% vs. 17.51% ± 8.57%; P < 0.001). However, no significant difference in the cytolytic activity was observed after surgery in the CRC patient group (before surgery, 8.82% ± 3.84% vs. after surgery, 9.95% ± 4.94%; P = 0.326). In addition, the percentage of peripheral blood natural killer cells was significantly higher in the preoperative patient group than in the healthy group (19.97% ± 11.51% vs. 15.60% ± 5.77%, P = 0.041). In contrast, the percentage of peripheral blood lymphocytes was lower in the preoperative patient group than in the healthy group (28.41% ± 8.31% vs. 36.4% ± 8.6%, P < 0.001). CONCLUSION These results demonstrate that circulating blood immune cells of CRC patients are functionally impaired and undergo an immunophenotypic perturbation, and show that a simple preparation of PBMCs can be useful to evaluate cellular immunity in cancer.