Nucleosomes and histones are present in glomerular deposits in human lupus nephritis

Recently we showed that antinuclear autoantibodies complexed to nucleosomes can bind to heparan sulphate (HS) in the glomerular basement membrane (GBM) via the histone part of the nucleosome. Histones have been identified in glomerular deposits in human and murine lupus nephritis. In addition, a decreased HS staining in the GBM was found, most probably due to masking by deposition of antibodies complexed to nucleosomes.

In this study we first investigated whether histones or nucleosomes could be identified in glomerular deposits in human lupus nephritis, and secondly whether the presence of these nuclear components was correlated with absence of HS staining. Kidney biopsies of SLE patients (11 with diffuse proliferative glomerulonephritis (DPGN) and six with membranous glomerulonephritis (MGN)) and non-SLE glomerular diseases were stained for histones. DNA, nucleosomes, IgG and HS.

Using a polyclonal anti-H3 1 21 antiserum, histones were detected in all patients with DPGN and in two of six patients with SLE-MGN (P < 0.01). Using a monoclonal antihistone antibody, histones were stained in three patients with DPGN, but in none of the biopsies with MGN. Using nucleosome specific monoclonal antibodies, nucleosomes were detected in five patients with DPGN, in two patients with MGN, but in none of the biopsies with non-SLE glomerulonephritis. HS staining was nearly absent in DPGN, whereas staining was only moderately reduced in patients with MGN and controls (P = 0.001).

Using polyclonal and monoclonal antihistone antisera, histones were identified in all patients with DPGN and their presence was associated with a decrease of HS staining. Nucleosomes were identified in five of 11 patients with DPGN and in two of six patients with MGN. This is the first demonstration of nucleosomes in glomerular deposits in SLE nephritis.