TUMOR-NECROSIS-FACTOR PRODUCTION BY GLOMERULAR MACROPHAGES IN ANTIGLOMERULAR BASEMENT-MEMBRANE GLOMERULONEPHRITIS IN RABBITS

The production of tumor necrosis factor (TNF) by nephritic glomeruli and glomerular macrophages was studied in antiglomerular basement membrane antibody induced glomerulonephritis (anti-GBM GN) in rabbits. Autologous phase injury was associated with glomerular macrophage infiltration and augmented TNF production by isolated nephritic glomeruli (day 8, 1.15 +/- 0.10 ng/10(3) glomeruli/24 hours; normal, 0.01 +/- 0.01 ng/10(3) glomeruli/24 hours; p < 0.05). In contrast, during the heterologous phase, in which macrophages were not prominent, injury was not associated with augmented glomerular TNF production. Glomerular TNF bioactivity had a molecular weight and isoelectric point consistent with rabbit TNF and was inhibitable by an anti-TNF antibody. TNF was also identified in nephritic glomerular supernatants by Western blotting. Macrophages isolated from glomeruli of rabbits developing autologous phase anti-GBM GN produced significantly more TNF (0.14 +/- 0.02 ng/10(3) macrophages/24 hours) than blood monocytes (0.03 +/- 0.02 ng/10(3) monocytes/24 hours, p < 0.05) from the same rabbits. Macrophage depletion of rabbits with autologous phase anti-GBM GN significantly reduced proteinuria, prevented glomerular macrophage accumulation, and blocked augmentation of glomerular TNF production. These studies demonstrate the association of glomerular TNF production with the development of glomerular macrophage infiltration and injury in anti-GBM GN and suggest that infiltrating glomerular macrophages are the major source of glomerular TNF.