Tonsil T Cell Immunity to Human Papillomavirus in the Absence of Detectable Virus in Healthy Adults

Abstract

Human papillomavirus (HPV) is known to infect the epithelium of the upper aerodigestive tract; however, major questions regarding prevalence and persistence of infection, and their relation to local immune response, remain unanswered. To evaluate the tonsil T cell immune response to HPV and compare this to the frequency of detectable virus at this site. A cross-sectional study of cancer-free adults undergoing routine tonsillectomy. Mucosal immune responses to recombinant HPV16 L2E6E7 and HPV6 L2E7 antigens were measured by tonsillar T-lymphocyte proliferation assay in 13 subjects. HPV deoxyribonucleic acid (DNA) was assessed by PCR and reverse line-blot hybridization in an expanded population of 44 subjects. Proliferative T-cell responses to HPV16 and HPV6 were identified in all patients. The presence of a CD45RO+ T cell population responsive to HPV6 L2E7 was confirmed in three of six subjects tested. There were no CD45RO+ responses to HPV16 L2E6E7 and no evidence of current or latent HPV infection of the tonsil. T cell memory to human papillomavirus can be identified in tonsil tissue from an adult population in the absence of concurrent HPV infection. How novel HPV vaccines might augment this preexisting cell-mediated immunity is an essential area for investigation.