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

Abstract

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.

Keywords: Blood cells; Colorectal neoplasms; Immunologic cytotoxicity; Natural killer cells.

Conflict of interest statement

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1

Peripheral blood mononuclear cell (PBMC) cytolytic activity against K562 cells for two different methods in preoperative patients with colorectal cancer (n = 18) and healthy donors (n = 18). (A) 5 × 105 PBMCs were cocultured with 2 × 104 K562 cells in a ratio of 25:1 for 2 hours. (B) An unfixed number of PBMC isolated from 500 µL of blood was cocultured with 2 × 104 K562 cells for 2 hours. Values are expressed as mean ± standard deviation. *Designates that P-value against the healthy group is less than 0.001 (Student t-test).

Fig. 2

Peripheral blood mononuclear cell (PBMC) cytolytic activity against K562 cells in patients with colorectal cancer (n = 94) and in healthy donors (n = 112). An unfixed number of PBMCs derived from 500 µL of blood was cocultured with 2 × 104 K562 cells for 2 hours. Values are presented as mean ± standard deviation. *Signifies that P-value against the healthy group is less than 0.001 (Student t-test).