Apoptosis‐associated proteins in oral hairy leukoplakia

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Abstract
OBJECTIVE To test the hypothesis that the anti-apop totic ability of Epstein-Barr virus (EBV) may result in altered expression of apoptosis-associated proteins in oral hairy leukoplakia (HL), we evaluated HL tissue and normal epithelium for these proteins by immunohistochemistry. MATERIALS AND METHODS Twenty formalin-fixed, paraffin-embedded specimens of HL lesions and six spedmens of normal control mucosa were selected from archived tissue specimens. Bcl-2. Bcl-x, Bax and p53 apoptoris-associated proteins were evaluated in immu-nohistochemically stained tissue sections according to staining intensity and pattern. The percentage of p53-positive burl cells was estimated in sequential fields. RESULTS: Generalty, there were only slight differences in the expression of Bcl-2 and Bcl-x proteins in the epithelium of HL and control tissue. The staining for Bcl-2 was weaker in keratinocytes than in putative melano-cytes and Langerhans cells. Equivocal diffuse cytoplasmic staining of prickle cells was also noted. Keratinocytes throughout the epithelium stained positively for Bcl-x protein, although upper layers were more weakly stained. The ‘balloon’ keratinocytes in HL were infrequently positive for Bcl-x. Bax staining in HL differed from that in control tissue in being more heterogeneous. The staining reaction in HL was weak to negative in upper epithelial levels where ‘balloon’ keratinocytes were located. Weak to moderate nuclear p53 protein staining was detected in a mean of 25.3% of basal keratinocytes in all but one of the HL specimens; weak staining was seen in only two control specimens. CONCLUSIONS: We found only slight immunohistochemid evidence that expression of the apoptosis-associated proteins is altered in HL. p53 appears to be over-expressed in HL; we speculate that this may be related to upregulation or stabilization of wild-type p53 protein related to EBV infedon.