Increase of Peripheral Blood B Cells with Fc Receptor for IgA in Patients with IgA Nephropathy

Abstract

A B‐cell subset with Fc receptors for IgA (Bα cells) has been observed in human peripheral blood. To investigate aberrations of B cells in a diseased state, the percentages of Bα cells were enumerated in peripheral blood from patients with IgA nephropathy, which is characterized by preponderant deposition of IgA‐dominant immune complexes in the glomerular mesangial area. The present study showed a significant increase in Bα cells in peripheral blood from patients with IgA nephropathy but not in those with chronic proliferative glomerulo‐nephritis without mesangial IgA deposition. Most FcαR‐bearing cells were observed in surface IgA bearing lymphocytes. No linear correlation was observed between the levels of serum IgA and the percentages of Bα cells. The addition of aggregated IgA to cultures did not induce FcαR‐bearing B cells in vitro. It is postulated that Bα cells might have some pathogenetic role in the development of IgA nephropathy and that some antigenic stimuli might play a role in the increase of peripheral blood Bα cells in patients with IgA nephropathy.