Detection of Human Papillomavirus and Expression of MHC Class I in Laryngeal Squamous Cell Carcinoma

후두편평세포암종에서 Human papillomavirus의 검출과 주조직적합복합체(Major Histocompatibility Complex: MHC) Class I 발현양상

The development of preneoplastic and neoplastic squamous cell proliferations of body sites such as the skin, female lower genital tract, and larynx is strongly associated with specific types of human papillomaviruses (HPV). Antitumor $CD^{8+}$ cells recognize peptide antigens presented on the surface of tumor cells by major histocompatibility complex (MHC) class I molecules. The MHC class I molecule is a heterodimer composed of an integral membrane glycoprotein designated the alpha chain and a noncovalently associated, soluble protein called beta-2-microglobulin( $\beta$ -2-m). Loss of $\beta$-2-m generally eliminates antigen recognition by antitumor $CD^{8+}$ T cells. We evaluated the expression of $\beta$-2-m as a potential means of tumor escape from immune recognition and the presence of HPV DNA as a cause of laryngeal squamous cell carcinomas (SCCs). Laryngeal SCCs (n=39) were analyzed for MHC class I expression by immunohistochemistry and for presence of HPV by in situ hybridization technique. The results were as follows : 1) HPV DNA was detected in 10 (25.64%) out of 39 cases in laryngeal squamous cell carcinomas. 2) MHC class I down-regulation (heterogenous and negative expression) in HPV positive lesions was higher than HPV negative lesions. 3) The expression of MHC class I was related to cellular differentiation regardless of T-stage and nodal involvement. In conclusion, HPV was thought to be the etiological factor of SCC of larynx, and we found that the down-regulation of MHC class I was a common phenomenon In laryngeal SCC and may provide a way for tumor cells to escape from immune surveillance.