Immunoregulatory function of HLA G in gastric cancer.
BACKGROUND Human leukocyte antigen (HLA) G positive gastric cancers are associated with poor survival, but links with tumor escape mechanisms remain to be determined. MATERIALS AND METHODS We used immunohistochemistry to investigate HLA G expression, tumor infiltrating CD8+ T lymphocytes, and Treg cells in 52 gastric cancer patients. RESULTS There were 29 cancer related deaths during the follow up period. Kaplan Meier analysis indicated that patients with HLA G positive (n=16) primary tumors had a significantly poorer prognosis than patients with HLA G negative tumors (n=36, p=0.008) The median survival time was 14 months and 47 months, respectively. Patients with high numbers of Tregs and low numbers of CD8+T lymphocytes in the primary tumor had a poorer prognosis than those with low numbers of Tregs and high numbers of CD8+T lymphocytes (p=0.034, p=0.043) Multivariate Cox proportional hazard regression analysis showed that HLA G expression (hazard ratio: 2.662; 95% confidence interval: 1.242 5.723; p=0.012) and stage (hazard ratio: 2.012;95% confidence interval: 1.112 3.715; p=0.041) were independent unfavorable factors for patient survival. CONCLUSIONS We found a significant positive correlation between HLA G expression and the number of tumor infiltrating Tregs (p=0.01) and a negative correlation with the number of CD8+T lymphocytes (p=0.041) HLA G may protect gastric cancer cells from cytolysis by inducing Foxp3+Treg lymphocytes and suppressing CD8+T lymphocytes.
Asian Pacific journal of cancer prevention APJCP