Highly expressions of activated cell surface markers and drug-resistance gene ABCG2 in cytokine-induced killer cells derived from umbilical cord blood

Objective: To analyze the proliferation and differential expressions of activated and inhibitory cell surface markers, drug-resistance gene A5CG2 and stem cell transcription factors in cytokine-induced killer cell (CIK) derived fro u bilical cord blood or peripheral blood in cancer patients, and to explore the superiority of u bilical cord blood de- rived-CIKs (CB-CIKs) in adoptive cellular immunotherapy. Methods: Cord blood mononuclear cells (CBMNCs) and pe- ripheral blood mononuclear cells in cancer patients were isolated using Ficoll-Plaque density gradients and incubated with cytokines. The proliferation, immunophenotypes, activated cell surface markers (CD28, CD27) and inhibitory cell surface marker (PD-1) were analyzed by flow cytometry, and the drug-resistance gene A5CG2 or stem cell transcription factors (c-Myc, Nanog, 0ct~4 and Sox2) w ere detemiined by RT-PCR. Resu Its: CB-CIKs and peripheral blood derived-CIKs (PB-CIKs) started to proliferation on the fourth day in vitro, and the proliferation index of CB-CIKs was statistically significantly higher than that of PB-CIKs on day 10 ([251. 52 ±16. 76] vs [158. 00 ±43. 19], P <0.05]. Thirteen days after incubation, the proportion of CD3⁺ CD56⁺ cells in CB-CIKs was higher than that in PB-CIKs ([21.20 ±4.82]% vs [10. 06 ±3.46]%, P < 0. 05). When detecting the status of CIKs, the proportions of activated CD4 ⁺ CD28 ⁺, CD4 ⁺ CD27 ⁺ and CD8⁺ CD27 ⁺ cells were significantly higher in CB-CIKs than PB-CIKs ([32. 40 ±16. 81]% vs [18. 65 ±9. 23]%; [27.48 ±13.53]% vs [0.98 ±0.55]%; [41.76±13.98]% vs [2.58 ±2. 10]%, P<0.05 or P <0.01), while the proportion of inhibitory CD8 ⁺ PD-1 ⁺ cells was significantly lower in the CB-CIKs ([3.25 ±2.13]% vs [8.05 ± 9. 23]%, P <0.01). The stem cell transcription factors (c-Myc, Nanog, Oct-4 and Sox2) were expressed both in CB-CIKs and PB-CIKs. Moreover, no significant differences were found between the two kinds of CIKs. Furthemiore, only CB-CIKs expressed high level of drug-resistance gene ABCG2. Conclusion: Compared with the PB-CIKs, the CB-CIKs demonstrate increased proliferation rates, higher expressions of activated surface markers, and lower expression of inhibitory surface marker. Besides, drug-resistant gene ABCG2 is highly expressed in CB-CIKs, showing several advantages in applying to tumor adoptive cellular immunotherapy.