Dendritic cell immunotherapy combined with cytokine-induced killer cells promotes skewing toward Th2 cytokine profile in patients with metastatic non-small cell lung cancer

• Th2 cytokines were dominant in the systemic environment for tumor-bearing patients.
• Th2 cytokines were dominant in the systemic environment for tumor-bearing patients.
• Systemic VEGF overproduction was associated with increased concentrations of IL-4 in tumor-bearing patients.

Dendritic cell (DC) vaccination and cytokine-induced killer (CIK) cell therapy (DC/CIK) have shown limited success in the treatment of advanced non-small cell lung cancer (NSCLC). To investigate the reason for this limited success, the effects of DC/CIK cell therapy on the immune responses of tumor-bearing patients and patients with resected NSCLC were evaluated. In the total 50 patients studied, the serum concentrations of the Th2 cytokines (IL-4 and IL-10) in tumor-bearing patients were significantly higher than those with resected NSCLC before immunotherapy. The post-therapy Th1 cytokine (IFN-γ) level in patients with resected NSCLC significantly increased from the pre-therapy level. In contrast, significantly enhanced post-therapy Th2 cytokine (IL-4 and IL-10) levels were found in tumor-bearing patients. The intracellular staining assay revealed that DC/CIK cell therapy increased the IFN-γ-producing T lymphocyte (CD8+IFN-γ+) frequency in patients with resected NSCLC, but these lymphocytes were not found in tumor-bearing patients. Furthermore, overproduction of vascular endothelial growth factor (VEGF) in tumor-bearing patients showed a statistically positive correlation with IL-4, suggesting that VEGF might be responsible for the predominance of serum Th2 cytokines. In a word, tumor-bearing patients developed a Th2-dominant status that could not be reversed toward Th1 following immunotherapy. A combined regiment of DC vaccination and CIK cell therapy with other treatments to overcome systemic Th2-dominant immune response might improve the current clinical benefit.