Langerhans cells and T cells in oral graft versus host disease and oral lichen planus

Chronic graft versus host disease (cGVHD) of the oral mucosa, following all ogeneic stein cell transplantation, and oral lichen planus (OLP) are both m ucosal diseases where the immune system is involved in the pathogenesis. Al though the aetiology of the two conditions is different, they present with a similar clinical appearance. This study compares the two diseases regardi ng the distribution of cells, which are expressing cell surface markers of interest for inflammatory responses. Monoclonal antibodies (MoAbs) were use d in standard immunohistochemical procedures. CD1a+, CD80+ and CD86+ cells in the epithelium of OLP-and cGVHD lesions had the dendritic morphology of Langerhans cells (LC). Higher frequencies of CD1a+ LC as well as CD25+ cell s were observed in the OLP epithelium than in the cGVHD epithelium. The OLP lesions showed higher frequencies of subepithelial cells expressing CD1a, CD86, CD4, CD8 and CD25 than the cGVHD lesions. Notably there was a signifi cantly higher frequency of CD25+ cells in the epithelium and the connective tissue of OLP than in cGVHD. These cells might represent regulatory T cell s. In conclusion, cGVHD and OLP show marked differences at the cellular lev el despite similar clinical appearance. Hence, the findings indicate differ ences in the regulation of the inflammatory response between the two condit ions.