Abstract 3238: Imbalance of circulating monocyte subsets in patients with squamous cell carcinoma of the head and neck

Abstract

Abstract Introduction: Human circulating monocyte is classified as three populations according to CD14 and CD16 expression: CD14+CD16- classical monocytes, CD14+CD16+ intermediate monocytes and CD14dimCD16+ nonclassical monocytes. Recent studies have unveiled the specific surface molecules and functions of each subset; however their dynamics in patients with cancer still remains unclear. In this study, we evaluated the proportions and the expressions of immunological/angiogenic molecules of the monocyte subsets in peripheral circulation in patients with squamous cell carcinoma of the head and neck (SCCHN). Materials and Methods: Peripheral blood mononuclear cells were isolated from 9 patients with SCCHN and age-matched 4 healthy donors. The 3 monocyte subsets were identified according to CD14/CD16 expressions using multi-color flow cytometry. Mean fluorescence intensities of various HLA molecules and angiogenic markers were analyzed. Results: Percentage of CD14+CD16+ intermediate monocyte among total monocyte tended to decrease in SCCHN patients than that in normal donors (p = 0.079). Higher surface expression of immunosuppressive HLA-G molecule on circulating classical (p = 0.045) and intermediate (p = 0.052) monocyte was observed in patients with SCCHN. An immunosuppressive receptor ILT4 showed tendency to increase on nonclassical monocyte (p = 0.061). Moreover, intracytoplasmic level of milk fat globule-EGF factor 8 (MFG-E8) in association with phagocytosis and angiogenesis tended to increase in intermediate (p = 0.064) and nonclassical (p = 0.052) monocytes of SCCHN patients. Discussion and Conclusion: CD16+ intermediate and nonclassical monocytes have been reported as mature, proinflammatory and angiogenic population in periphery. In the present study, we showed possible alternations of these subsets in patients with SCCHN. Furthermore, increasing surface expressions of immunosuppressive molecules HLA-G and ILT4 on circulating monocytes implied immunological deterioration in cancer patients. However the sample size is still small, our preliminary data strongly suggests proportional and functional changes of peripheral monocyte subsets in SCCHN patients. Further analyses in more patients are currently underway. Citation Format: Koichi Sakakura, Hideyuki Takahashi, Sei-ichiro Motegi, Kazuaki Chikamatsu. Imbalance of circulating monocyte subsets in patients with squamous cell carcinoma of the head and neck. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3238.