EGF and EGF-r immunoexpression in Sjögren's syndrome secondary to rheumatoid arthritis. Correlation with EBV expression?

Minor labial salivary gland biopsies from 25 patients with secondary Sjögren's syndrome (SS) suffering from rheumatoid arthritis and from 11 patients complaining of ocular dryness associated with rheumatoid arthritis without proven SS, were studied for the immunohistochemical expression of Epidermal Growth Factor (EGF) and its receptor (EGF-r). Minor labial salivary glands from 11 healthy individuals were used as the control. Furthermore, the results were correlated with data retrieved from a previous study on EBV expression by the in situ hybridization method in the same specimens. In 16/25 cases of secondary SS the epithelial duct cells expressed both EGF and EGF-r, particularly in the areas of lymphoepithelial lesion and tissue destruction. Eleven of these cases expressed a positive EBV hybridization signal. In contrast, only 3/11 patients with ocular dryness and 2/11 cases from the group of healthy individuals showed immunoreactivity for EGF/EGF-r. A positive EBV signal was detected in 3/11 and 1/11 of these cases, respectively. These results indicate that EGF and EGF-r may play a crucial role in the evolution of the disease under the constant influence of EBV, which seems to up-regulate the expression of the EGF/EGF-r system.