Figure 2.

Expression of P2X₅ and P2X₇ receptors in paraffin sections of human warts. Nuclei were counterstained blue with haematoxylin. (a) Low power view of P2X₅ immunoreactivity (brown) in the wart. P2X₅ receptors were present within the keratinocytes of the wart. There was marked hyperkeratosis (H), which was negative for P2X₅ receptors, although areas of parakeratosis were positive (arrow). At the outer edge of the stratum corneum there was a band of heavy staining (asterisk). P2X₅ receptors were also found in the inflammatory cell infiltrate (I) above the stratum corneum (SC). There was a prominent granular layer (SG), within which cells (koilocytes) showed typical cytoplasmic vacuolation (arrowheads). Scale bar. 100 μm. (b) Low power view of P2X₇ immunoreactivity (pink) in the wart. P2X₇ receptors were strongly present within the hyperkeratotic (H) areas of the stratum corneum (SC), but not in areas of parakeratosis (arrow). P2X₇ receptors were weakly present in the wart keratinocytes, and mainly found in the nucleus. P2X₇ receptors were also weakly found in the inflammatory cell infiltrate (I) above the stratum corneum. Scale bar, 100 μm. (c) High power view of P2X₅ immunoreactivity (brown) in wart keratinocytes. There were a few positive cells in the basal layer (B), but most of the positively stained cells were in the suprabasal layers. Koilocytes showed P2X₅ receptor staining in the nucleus (arrowheads). Scale bar, 50 μm. (d) P2X₇ immunoreactivity (pink) was present in the suprabasal layers of the wart, in either large, flat nuclei with an obvious nuclear membrane (arrow), or in koilocytes, where the receptor was prominent in shrunken, pynotic nuclei, (arrowheads). P2X₇ receptors were not found in the basal layer (B) of the wart. Scale bar, 50 μm. (e) There was residual staining of the outermost edge of the stratum corneum (asterisk) with the P2X₅ receptor antibody no primary control, and therefore this was non-specific staining. Scale bar, 100 μm. (f) There was no staining in keratinocytes of the wart with the P2X₅ receptor antibody no primary control. There was some melanin in the basal layer (B) of the wart. Scale bar, 50 μm.