Laser‐capture microdissection of oropharyngeal epithelium indicates restriction of Epstein–Barr virus receptor/CD21 mRNA to tonsil epithelial cells

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Abstract
Background: Epstein–Barr virus colonizes the oropharynx of a majority of individuals. It infects B lymphocytes and epithelial cells and can contribute to the development of both lymphoid and epithelial tumors. The virus uses CD21 for attachment to B cells which constitutively express the protein. Infection of epithelial cells in vitro is also more efficient if CD21 is available. However, its potential contribution to infection in vivo has been difficult to evaluate as discrepant results with antibodies have made it difficult to determine which, if any, epithelial cells in the oropharynx express CD21. Methods: To reevaluate CD21 expression by an alternative method, epithelial cells were isolated by laser‐capture microdissection from formalin‐fixed sections of tissues from various parts of the oropharynx and mRNA was amplified with primers specific for the exons of CD21 which code for the Epstein–Barr virus binding site. Results: CD21 mRNA was expressed in tonsil epithelium, but not in epithelium from buccal mucosa, uvula, soft palate or tongue. Conclusions: CD21 does not contribute to infection of most normal epithelial tissues in the oropharynx, but may contribute to infection of epithelial cells in the tonsil, where virus has been demonstrated in healthy carriers.