Loss of HLA-DR expression is related to tumor microenvironment and predicts adverse outcome in diffuse large B-cell lymphoma.

The interaction between tumor cells and the tumor microenvironment is essential in the development and progression of diffuse large B-cell lymphoma (DLBCL). Loss of human leukocyte antigen DR (HLA-DR) in DLBCL is a robust adverse prognostic marker. We evaluated the immunohitochemical expression of HLA-DR in lymphoma and the biologic implications of the loss of HLA-DR. The loss of HLA-DR correlated with clinical stage (p < 0.05), International Prognosis Index (p < 0.05), soluble interleukin-2 receptor (p < 0.05) and poor outcome in patients with DLBCL, especially among elderly patients. Flow cytometry analysis of the infiltrating T-cells showed that the mean CD4 + CD25 +/CD8 ratio of the infiltrating T-cells was higher in the HLA-DR positive group than in the HLA-DR negative group (p < 0.05). These data suggest that loss of HLA-DR expression in DLBCL decreases the ratio of helper T-cell within the T-cell population in the tumor microenvironment and might contribute to escape from immunosurveillance.