An analysis of polyclonal B cell activation in Sjögren's syndrome. Characterization of B cell lines spontaneously established from the peripheral blood.

We intended to analyze the mechanism of polyclonal B cell activation in patients with Sjögren's syndrome (SS). Peripheral blood mononuclear cells (PBMC) were grown in bulk cultures without stimulation. Four cell lines (SS-1, SS-7, SS-10, SS-14) were successfully established from SS patients but none from normal controls. All of the cell lines were B cell origin possessing B1, B4 and HLA-DR antigens on their surfaces and were positive for EB virus associated nuclear antigens (EBNA). Both SS-7 and SS-10 spontaneously produced IgM whereas SS-1 and SS-14 IgG. All the cell lines except SS-7 expressed receptors for B cell stimulatory factors (BSF). Culture supernatants of these cell lines contained multiple biological activities including those for IL-1, IL-2, IL-3 and BCGF. These data suggest that B cells are polyclonally activated in vivo presumably by EB virus in SS and these activated B cells might perturb immunoregulatory system by producing multiple lymphokines.