Myeloid derived suppressor cells (MDSCs) can be induced or expanded in tumor-bearing mice and cancer patients. The frequency of MDSCs denoted here as Lin-/low CD33+ HLA-DR- was investigated in hepatocellular carcinoma (HCC) patients. The clinical relevance of MDSCs and patients' characteristics were examined. And MDSC-related immune regulatory pathway in these patients were discussed.
The population of MDSCs was tested in peripheral blood of patients with HCC (n=63) and healthy donors (n=56). The expressions of IFN-γ, VEGF, COX-2, MMP-13 NOS-2 and ARG-1 were analyzed. Coculturing with anti-CD3/CD28-stimulated T lymphocytes was used to determine the suppressive effect of MDSCs on the T lymphocytes.
Patients with treatment-naive HCC had an increased subpopulation of Lin-/low CD33+ HLA-DR- cells in the PBMCs with characteristics of MDSCs and associated to the stage (P =0.0004). Patients with splenomegaly had a higher frequency of circulating MDSCs. Also COX-2, MMP-13 and VEGF were expressed differently associated with the alteration of MDSCs.
Our study provide evidence showing an increased population of Lin-/low CD33+ HLA-DR- MDSCs in the peripheral blood of HCC patients. Our data also suggest that MMP-13 and COX-2 in PBMC may play a new important role companied with MDSCs in HCC patients.