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Changes in the expression of integrins and basement membrane proteins in benign mucous membrane pemphigoid
J Jones1, C S Downer, P M Speight
1Department of Oral Pathology, Eastman Dental Institute for Oral Health Care Sciences, University of London, UK.
Objective:
To determine the location of the subepithelial split in benign mucous membrane pemphigoid (BMMP) and its relationship to the anchoring filaments and their receptors.
Materials And Methods:
Frozen sections of lesional and perilesional oral mucosa from 10 cases of BMMP were stained, using an immunofluorescence method, for the beta-1, beta-4, alpha-3 and alpha-6 integrin subunits and for their ligands, laminin I and laminin V (kalinin). In all cases the diagnosis was confirmed by the demonstration of linear staining for IgG at the basement membrane zone. Six specimens of normal mucosa were stained for comparison.
Results:
Staining for integrins, laminin and kalinin in perilesional mucosa was similar to normals, although one case showed loss of alpha-6 and beta-4 . In lesional mucosa, laminin and kalinin showed strong linear staining localised to the floor of the bullae. The alpha-6 and beta-4 subunits were expressed only on the roof of the bullae but staining was weak and patchy with areas of loss. In some sections alpha-6 showed a punctate intracellular distribution similar to IgG. The distribution of alpha-3 and beta-1 was similar to that seen in normals.
Conclusions:
In all cases kalinin was found on the connective tissue side of the lesions and alpha-6 beta-4 localised to the epithelial side. This shows that the split occurs at a location which separates anchoring filaments from the hemidesmosomes. Loss of the alpha-6 beta-4 integrin in the lesions and the similar intracellular staining of alpha-6 and IgG, suggest that disruption of hemidesmosomes may be a key event in the immunopathogenesis of the lesions and that the alpha-6 integrin subunit is a potential antigen in oral mucosal BMMP.