Effect of Epstein-Barr virus replication on Langerhans cells in pathogenesis of oral hairy leukoplakia.

Epstein-Barr virus (EBV) replicates productively in oral hairy leukoplakia (HLP). One characteristic of human immunodeficiency virus (HIV)-associated HLP is a decreased oral epithelial Langerhans cell count. This prospective study tested the hypothesis that oral epithelial EBV replication decreases oral Langerhans cell counts. EBV replication in HLP was highly correlated with decreased oral Langerhans cell counts. Inhibition of EBV replication restored oral Langerhans cell counts to normal control levels, and the return of EBV replication after treatment resulted in a recurrent decline in oral Langerhans cell counts. Decreased oral Langerhans cell counts occurred independently of HIV infection, as demonstrated in HLP of otherwise healthy HIV-seronegative individuals. These results support the tested hypothesis and suggest that EBV manipulates and evades the mucosal immune response in oral epithelial infection. This novel EBV strategy for eliminating oral Langerhans cells may facilitate the persistence of oral epithelial EBV and may contribute to the pathogenesis of HLP.