IgG4 deposits in pure and combined membranous lupus nephritis

The aim of this study is to determine the frequency and prognosis of IgG4 deposits in renal biopsy of patients with membranous lupus nephritis (MLN). This is a retrospective cohort study in which we included patients with class V alone or combined (III/V or IV/V) of lupus nephritis according to the 2004 ISN/RPS. All the patients included must have availability of renal tissue for immunohistochemistry analyses. We excluded other classes of lupus nephritis. The renal tissue was examined by a nephro-pathologist. We included 65 patients with MLN; of these, 24 (37 %) were class V, and the other had proliferative concomitant with membranous patterns. Seven renal specimens had IgG4 deposits (10 %). Patients with IgG4 deposits had higher levels of eosinophils in serum. All of the patients with IgG4 had renal involvement as first manifestations of systemic lupus erythematosus. The rate of renal failure was 42 and 43 % in IgG4 positive and negative, respectively, 28 % of IgG4 required renal replacement therapy. From a histological view, 42 % of IgG4 had evidence of arteriolar vasculitis in renal biopsies. Lupus patients with IgG4 deposits were more likely to have renal involvement as a first manifestation of systemic lupus erythematosus, and they course with a worse prognosis since they required more dialysis. Also, they have more probability of vascular inflammation on the renal biopsy.