We recently identified 3 fractions of human peripheral blood (PB) dendritic cells (DC), including the monocyte-associated fractions 1 and 2 (CD1a+,CD11c+ and CD1a-,CD11c+, respectively) and the lymphoid-associated fraction 3 (CD1a-,CD11c-). We attempted to determine whether these fractions were altered in Sjögren's syndrome (SS).
We examined 23 patients with primary SS and 22 normal control subjects. DC were purified from PB and analyzed by flow cytometry. Immunohistochemical staining of labial salivary glands of SS patients was performed with monoclonal antibodies against fascin, which is known to be specific for DC.
The total numbers of PB DC and fraction 1 DC were decreased in SS. Immunohistochemical staining demonstrated that fascin+,CD11c+,HLA-DR+ mononuclear cells were present and scattered among numerous fascin-hyperfiltrating cells in SS patients. Interferon-gamma (IFNgamma)-producing Th1 cells were shown to be increased in both PB and salivary glands of patients, indicating the presence of general IFNgamma-producing Th1 polarization in SS. Furthermore, numbers of Thl cells were increased when naive T cells were cocultured with fraction 1 DC in vitro.
These findings suggest selective trafficking of fraction 1 DC into focal sites of inflammation and subsequent promotion of Th1 balance, suggesting a novel pathogenesis of SS.