Characterization of the mononuclear cell infiltrate in the glomerulus of rats with glomerulonephritis

Bone marrow-derived inflammatory cells contribute to glomerular damage in experimental glomerulonephritis. The time sequential appearance and the pattern of inflammatory cells in the diseased glomerulus is, however, unclear. We therefore characterized the inflammatory cell infiltrate in a model of unilateral in situ immune complex glomerulonephritis. The cellular infiltrate was specific for the diseased kidney and independent of changes in peripheral blood or spleen. We found an influx of leukocyte common antigen (LCa)-positive and ED1-positive (monocytes/macrophages) cells in isolated glomeruli as early as 24 h after induction of the disease. Lymphocytes of the CD4-, CD8- and CD20-positive phenotypes were present in diseased glomeruli at Day 10. Complement depletion prevented the influx of monocytes/macrophages at 24 h in the glomerulus, which indicates that complement activation is important for the glomerular cell infiltrate at this early time point. The results demonstrate that the inflammatory cell infiltrate is regulated in situ at the glomerular level and not accompanied by similar changes in peripheral blood and spleen cells.