Differential reactivity of anti-E-selectin monoclonal antibodies in human gingival tissue

E-selectin is a cytokine-inducible endothelial glycoprotein which participates in the binding of leukocytes to vascular endothelium. Variable levels of expression of E-selectin have been reported in gingivitis and periodontitis, and two differing concepts of its significance have emerged: either gingival blood vessels express E-selectin constitutively, or are continuously activated by inflammatory mediators arising from the gingival environment. A range of monoclonal antibodies reacting with different epitopes of E-selectin are available commercially. The present study explored the possibility that the choice of antibody could affect estimation of the level of expression of E-selectin in vivo. Five monoclonal antibodies were used to investigate E-selectin expression in serial cryosections of human gingival tissue. While E-selectin-positive vascular endothelial cells were detected with all antibodies, the number of positively staining endothelial cells varied, with BBA1 > H4/18 = H18/7 = 4D10 > 1.2B6. The frequency of strong staining in tissue specimens was BBA1 > 4D10 > H4/18 = H18/7 > 1.2B6, while the frequency of weak staining showed the reverse trend. Additionally, with antibodies H18/7 and 1.2B6, 17 and 36% of the specimens were E-selectin negative. The occurrence of what appear to be false positives and false negatives confounds estimation of the level of E-selectin expression. Based on these findings, patterns of endothelial E-selectin expression in gingivitis and periodontitis should be re-evaluated.