Immunologic determinants of susceptibility to experimental glomerulonephritis: role of cellular immunity

To identify the immunologic mechanisms that influence susceptibility to GN, we compared the severity of accelerated anti-glomerular basement membrane (GBM) nephritis between Lewis (LEW) and Brown Norway (BN) rats and analyzed differences in their immune responses to the nephritogenic immunoglobulin. Lewis (LEW) rats preimmunized with sheep IgG developed proliferative GN with marked proteinuria [peak protein excretion (mean +/- SEM) = 85.3 +/- 15.3 mg/24 hr; normal = 6.4 +/- 0.8 mg/24 hr] after receiving a subnephritogenic dose of sheep anti-rat GBM antiserum. Identically treated Brown Norway (BN) rats, on the other hand, had minimal renal pathology and minimal proteinuria (peak protein excretion = 22.6 +/- 3.1 mg/24 hr; normal = 13.0 +/- 0.6 mg/24 hr). Serum titers of rat anti-sheep IgG isotypes and intraglomerular binding of sheep IgG, rat IgG, and rat complement (C3) were comparable in both strains. In contrast, only LEW rats developed a strong cellular immune response to sheep IgG represented by intrarenal T lymphocyte (OX19+) and monocyte (ED1+) accumulation [LEW vs. BN (mean +/- SEM): OX19+ = 0.60 +/- 0.10 vs. 0.14 +/- 0.01 cells/glomerulus, control = 0.02 +/- 0.01; ED1+ = 4.0 +/- 0.4 vs. 1.0 +/- 0.2 cells/glom., control = 0.8 +/- 0.3] and a significant cutaneous delayed-type hypersensitivity (DTH) reaction [LEW versus BN (mean +/- SEM): delta ear thickness = 0.22 +/- 0.02 vs. 0.05 +/- 0.03 mm; control = 0.04 +/- 0.02 mm]. Upon rechallenge with sheep IgG in vitro, LEW splenocytes expressed a T helper 1 (Th1) cytokine pattern (IFN gamma and IL-2 mRNA, but little IL-4 mRNA) which is associated with delayed-type hypersensitivity reactions. BN splenocytes, on the other hand, expressed IL-4 in addition to IL-2 and IFN gamma mRNA that is consistent with an undifferentiated (Th0) cytokine profile. These studies suggest that humoral immunity to heterologous immunoglobulin planted in the kidney is not sufficient for full expression of accelerated anti-GBM nephritis, and that additional cellular immune mechanisms are required. We conclude that susceptibility to accelerated anti-GBM nephritis is strongly influenced by the host's propensity to mount a Th1-type response and DTH reaction to the disease-inciting immunoglobulin.