B-cell oligoclonal expansions in renal tissue of patients with immune-mediated glomerular disease.

B-cell clonal expansion has been sporadically described in the blood and/or renal tissue of patients with glomerulonephritides, albeit with unclear pathogenetic role. Herein, using spectratyping analysis, we observed oligoclonal intrarenal B-cell populations in 59% of glomerulonephritis patients with podocyte injury (6/7 with focal segmental glomerulosclerosis, 1/3 minimal change disease, 1/3 idiopathic membranous nephropathy, 3/4 IgA nephropathy, 2/5 membranous lupus nephritis), 20% of glomerulonephritis patients without podocyte involvement (4/13 with mesangial or proliferative lupus nephritis, 0/3 idiopathic membranoproliferative glomerulonephritis, 0/4 pauci-immune vasculitis) and 17% of control patients with renal cancer. In multivariate analysis, oligoclonal B-cells were associated with podocyte injury and the grade of glomerulosclerosis (both p = .009). B-cell oligoclonal expansions were not found in the paired peripheral blood samples. We postulate that B-cell expansion in the kidney results from local stimuli, including antigens expressed on podocytes. Further studies to unravel the role of oligoclonal B-cells in (auto)immune-mediated kidney disease are warranted.