Prognostic significance of HLA class I expression in Ewing's sarcoma family of tumors

Background: Ewing's sarcoma family of tumors (ESFT) is one of the most malignant groups of tumors in young people. Human leukocyte antigen (HLA) class I displays endogenously processed peptides to CD8+ T lymphocytes and has a key role for host immune surveillance. In ESFT, the investigation concerning both HLA class I expression and T-cell infiltration has yet to be reported. Methods: Biopsy specimens from 28 ESFT patients were evaluated by immunohistochemistry with the anti-HLA class I monoclonal antibody (mAb) EMR8-5 and anti-CD8 mAb, respectively. Results: Expression of HLA class I was negative in 10 tumors and down-regulated in 22 tumors. The status of CD8+ T cell infiltration was closely associated with the expression levels of HLA class I. ESFT patients with down-regulated or negative expression of HLA class I showed significantly poorer survival than the rest of the patients. Conclusions: Our results suggested that CD8+ T cell-mediated immune response restricted by HLA class I might play an important role in immune surveillance of ESFT, and we revealed for the first time that the status of HLA class I expression affects the survival of the patients with ESFT.