Significance of myeloid-derived suppressor cells (MDSCs) like CD14+B7-H4 cells frequency in blood and tumor microcirculation of lung cancer patients
Background / Aim. MDSCs suppress immune responses via a series of inhibitory mechanisms, which ultimately could lead to tumor growth. B7-H4 expression is significantly associated with poor outcome and promotion of tumor cell proliferation, invasion and migration in patients with various cancers. Data concerning B7-H4 expression in lung cancers, either on tumor or immunological cells, are still sporadically. To estimate and correlate the number of CD14+B7-H4+MDSC in blood and lung tumor microcirculation with clinical stage, histology type of tumor, TNM stadium, nodal status and disease outspread. Methods. 44 lung cancer patients (III and IV clinical stage) and 30 healthy controls. CD14+B7-H4+ MDSC number was estimated by flowcytometry in blood and tumor microcirculation samples of each patient. Results. CD14+B7-H4+MDSC number was significantly higher in patient’s samples comparing to controls. CD14+B7-H4+MDSC was significantly increased in tumor comparing to blood sample of same patient. Clinical stage III patients had increased number of the CD14+B7-H4+ MDSC comparing to stage IV, in both type of samples. According to histology SCLC patients had the highest average CD14+B7-H4+MDSC number, significantly increased comparing to patients with squamous and large cell LC histology in tumor. Tumor size was directly associated with the number of the CD14+B7-H4+MDSC, both in blood and tumor samples. Furthermore, nodal involvement was associated with gradual increase of the CD14+B7-H4+MDSC number, being the highest in the N3 group, again both in blood and tumor samples. Finally, we have detected higher CD14+ B7-H4+MDSC number in the samples of patients without metastases. Conclusion. CD14+B7-H4+MDSC number in LC patients is significantly associated with tumor histology type, lymph node involvement, disease extent degree and tumor size. Concerning their large number in LC tumor microenvironment together with immunosuppressive capacities, CD14+B7-H4+MDSC could represent important tumor promoting factor in LC pathophysiology.