LACK OF B7.1 AND B7.2 ON HEAD AND NECK-CANCER CELLS AND POSSIBLE SIGNIFICANCE FOR GENE-THERAPY

Cellular immunity mediated by cytotoxic T-cells plays a key role in ho st tumor defense. An optimal T-cell recognition is based primarily on the presentation of an antigen in the context with MHC Class I molecul es, secondarily co-stimulatory molecules, such as the B7 family, are n ecessary to initiate maximum stimulation. We examined the quality (imm unohistochemically) and quantity (FACS-analysis) of B7 expression on p rimary and permanently established head and neck squamous cell cancer (HNSCC). Neither on the primary nor on the permanently established HNS CC lines could B7 be detected. The lack of costimulatory molecules cou ld be the reason for the low immunogenicity of HNSCC. Future gene tran sfer of B7 could help to restore the immune function. Transfection of expression plasmids encoding B7 cDNA into the tumor cells by gene ther apy might restore tumor-specific immunity as a new tool for cancer era dication in the future.