The onset of nephritis in the (NZB x SWR)F1 murine model for systemic lupus erythematosus correlates with an increase in the ratio of CD4 to CD8 T lymphocytes specific for the nephritogenic idiotype (IdLNF1).

An idiotypically related family of nephritogenic antibodies (IdLNF1) has been shown to be important in the pathogenesis of autoimmune glomerulonephritis in the (NZB x SWR)F1 hybrid, SNF1. Idiotype-specific T lymphocytes which modulate expression of antibody bearing that idiotype may be important in the pathogenesis of systemic lupus erythematosus (SLE). Here, IdLNF1-reactive T lymphocytes were not only found to be present in the NZB, SWR, and SNF1, but a significantly (P < or = 0.05) greater number of IdLNF1-reactive Thy 1.2+ splenic lymphocytes were observed as early as 12 weeks of age in the SNF1. Further, a significant shift in the ratio of CD4+ to CD8+ IdLNF1-reactive T lymphocytes in favor of CD4+ IdLNF1-reactive T cells was observed at 20 to 24 weeks of age only in the SNF1. This shift correlated with an increase in IdLNF1+IgG, and deposition of IdLNF1 bearing immunoglobulin in the kidney glomeruli. These observations suggest a role for idiotype-specific T lymphocytes in the induction of glomerulonephritis in this murine model of SLE.