Oral lesions of lupus erythematosus patients in relation to other chronic inflammatory oral diseases: an immunologic study

The nature and distribution of mononuclear cells in non-ulcerated oral lesions of discoid (DLE) and systemic lupus erythematosus (SLE), were investigated and compared to other chronic inflammatory oral diseases (lichen planus (LP), contact lesion (CL), unspecified inflammation (UI), geographic tongue (GT), and leukoplakia (LK). For this purpose an immunoperoxidase technique based on staining with monoclonal antibodies was employed. In most LE specimens examined infiltrating cells consisted predominantly of a mixture of T cells (Leu 3a+ and Leu 2a+) that were distributed in the lamina propria, the submucosa, and occasionally also in the epithelium. In general, only few B cells were detected while macrophages were more frequent. In all LE specimens examined beta 2-microglobulin expression was observed on a large proportion of cells including infiltrating mononuclear cells as well as resident keratinocytes. In addition, most infiltrating cells displayed MHC Class II antigens according to a pattern HLA-DR greater than DQ greater than DP. Interestingly, expression of Class II antigens was also observed on epithelial keratinocytes but was restricted to HLA-DR and -DP gene products (DR much greater than DP). HLA-DQ expression was never observed on keratinocytes. In most LE specimens studied a small proportion (less than 5%) of inflammatory cells had detectable interleukin-2 receptors (IL-2R) and/or transferrin receptors (transf-R). However, expression of transf-R was also observed on basal epithelial cells, being more pronounced in DLE than in SLE lesions. The above staining patterns observed in LE lesions, when compared to other chronic inflammatory oral lesions, did not disclose any striking differences that could support the specific diagnosis of LE. However, the findings of Class I and II MHC gene products on oral keratinocytes suggest an important accessory role for these cells in directing the migration of activated lymphoid cells in the epithelium in chronic inflammatory lesions of the oral mucosa.