Immune complex glomerulonephritis following bone marrow transplantation in C3 deficient mice.

backgroundThe role of circulating complement in host defense and immune disease is well established. Although a number of cells and tissues are capable of synthesizing complement components locally, the importance of such local synthesis in immune disease has been difficult to establish. METHODOLOGY/PRINCIPAL

findingsWe used bone marrow transplantation (BMT) between C3 knockout (C3KO) and wild type (WT) mice to construct animals that were discordant for systemic (hepatic) and local (monocytic) C3 synthetic capacity. An immune complex glomerulonephritis (GN) was then induced using intraperitoneal injections of horse spleen apoferritin (HSA) with a lipopolysaccharide (LPS) adjuvant. All HSA/LPS animals developed a proliferative GN with glomerular infiltration by monocytes. By sensitive ELISA, monocyte C3 synthesis could be detected in C3KO animals transplanted with WT bone marrow cells. Despite this, there were no significant differences among groups of mice in measures of clinical (proteinuria, renal function) or histologic (glomerular cellularity, crescents) disease severity. CONCLUSIONS/SIGNIFICANCE: In this model of GN, local synthesis of C3 by infiltrating cells does not appear to be of pathologic importance.