Increased IgA and decreased IgG production by Epstein-Barr virus transformed B cells in culture in IgA nephropathy.

Despite many studies describing IgA upregulation both in vivo and in vitro in IgA nephropathy (IgAN), the underlying mechanism of increased IgA production is not known. In this study, Epstein-Barr virus was used to transform B cells in vitro in a T-cell-independent manner in order to investigate immunoglobulin production by B cells in IgAN. B cells from patients with IgAN produced more IgA and less IgG in culture than controls. While both IgA subclasses contributed to the increase in IgA production, only IgA1 synthesis was significantly higher than controls. These results of increased IgA production in patients with IgAN, with a concomitant decrease in IgG production, demonstrate hyperactivity of B cells restricted to the IgA isotype in IgAN.