B7-H1 Expression Model for Immune Evasion in Human Papillomavirus Associated Squamous Cell Carcinomas
Odey C Ukpo, Wade L Thorstad, James S Lewis. Washington University, Saint Louis, MO
Background: Human papillomavirus (HPV) has been associated with oropharyngeal squamous cell carcinomas (OSCC). Persistent viral infection is postulated as the mechanism leading to carcinogenesis. It is known that immune evasive cells can provide an ideal niche for a virus. The B7-H1/PD-1 cosignaling pathway plays an important role in viral immune evasion by making CD8+ cytotoxic T-cells anergic. Tumor cell B7-H1 expression has also been associated with poorer survival in numerous carcinomas, but its role in HPV-related OSCCs is unknown. We hypothesized that HPV-related OSCCs express B7-H1 as a potential mechanism for HPV immune evasion.
Design: A tissue microarray of OSCC was utilized, for which HPV E6/E7 mRNA by in situ hybridization was previously performed. Immunohistochemistry was performed to detect B7-H1 on tumor cells, which was scored as positive or negative. Either membranous or cytoplasmic staining was considered positive. Screening was performed by two pathologists (OCU, JSL), both blinded to clinical information.
Results: B7-H1 was expressed in 82 of the 181 (45.8%) cases. Tumors expressing B7-H1 were more likely to be HPV positive.
|B7-H1 Positive||B7-H1 Negative|
|HPV mRNA Positive||68||70|
|HPV mRNA Negative||14||27|