AIM-2: A novel tumor antigen is expressed and presented by human glioma cells

(A) under bar ntigen isolated from (I) under bar mmunoselected (M) under bar elanoma-2 (AIM-2) was recently identified using melanoma-reactive CD8(+) T cells. AIM-2 antigen is expressed in a wide variety of tumor types, including neuroectodermal tumors, as well as breast, ovarian and colon carcinomas. In this study, we analyzed AIM-2 expression in glioblastoma multiforme (GBM) in primary cultured cells and established GBM cell lines. We found that the primary GBM cell lines expressed 88.4% and 93.0% of non-spliced and spliced AIM-2, respectively. Five out of seven of the established GBM cell lines expressed both non-spliced and spliced AIM-2. Furthermore, the C9 CTL clone, which is specific for AIM-2 peptide (RSDSGQQARY), efficiently recognized GBM tumor cells in an antigen-specific and HLA-A1 restricted manner. IFN-gamma treatment of the GBM tumor cells dramatically increased HLA-A1 expression levels and, consequently, increased CTL recognition of the treated tumor cells. More importantly, seven out of 12 HLA-A1 and AIM-2 positive patients from our dendritic cell clinical trial generated AIM-2 specific CTL activity in their PBMC after vaccinations. These data indicate that AIM-2 could be used as a tumor antigen target for monitoring vaccine trials or to develop antigen specific active immunotherapy for glioma patients.