Masaharu Okuda

B Cell Hyperresponsiveness in Sjögren's Syndrome

We examined the production of and responsiveness to B cell growth factor (BCGF) by using proliferation assays in patients with Sjögrens syndrome (SS). We also studied the ability of SS B cells to respond to B cell stimulatory factors (BSF) by measuring the amount of IgG produced in vitro. SS patients showed normal production of and responsiveness to BCGF. They were also demonstrated to show a normal response to Staphylococcus aureus Cowan I (SAC). In addition, cell surface antigens of B cells in the peripheral blood of SS patients were not altered compared with normal controls. However, SS B cells produced a significant amount of IgG in vitro in response to BSF stimulation with or without anti-IgM antibody. Furthermore, there was a positive correlation between the hyperresponsiveness of B cells to BSF in vitro and serum IgG level in SS. We, therefore, suggest that the enhanced response of B cells to BSF might contribute to polyclonal B cell activation in SS.

Discordant Interleukin 2 Production in Monozygotic Twins Concordant for Systemic Lupus Erythematosus

We present data from monozygotic twins concordant for SLE. IL-2 production by peripheral blood mononuclear cells from the patients, when they were discordant for SLE activity, were measured employing cellular mixing experiments. Macrophages from active SLE had a suppressive effect on IL-2 production. Furthermore, SLE T cells appeared to have a defect in IL-2 production irrespective of disease activity. These defects might play an important role in the disordered immunoregulation in SLE.