Expression of complement restriction factors (CD46, CD55 & CD59) in head and neck squamous cell carcinomas

Background: Tumor cells can escape complement‐dependent cytotoxicity (CDC) by expressing complement restriction factors (CRFs), CD46, CD55 and CD59. CRF‐expression in non‐neoplastic mucosa of the head and neck was compared with biopsies of the head and neck squamous cell carcinoma (HNSCC) and cell lines derived from oral squamous cell carcinomas (OSCC). Methods: Normal mucosa and HNSCC tumor tissue (poor, moderate, or well differentiated) specimens were immunostained with anti‐CRF monoclonal antibodies. Immunostaining of the OSCC cell lines (SCC12 and SCC71) was examined under laser scan fluorescence microscopy. Results: CD46, CD55 and CD59 were highly expressed in HNSCC cells including T1/T2N0M0 stages. The CRF expression was much lower or absent in non‐neoplastic squamous epithelia or in the submucosa of both normal and tumor tissues. Conclusions: Enhanced staining of tumor tissues at stages T1/T2 indicates that the CRFs are overexpressed by primary tumors before metastasis to either lymph nodes or organs (N0M0 stage) suggesting that CRFs are formed early during tumorigenesis.