This study examines the clinical and immunopathological features of spontaneous lupus-like syndromes in several murine strains, including NZB × W, MRL/l, and BXSB mice. These strains exhibit similar clinical and immunopathological characteristics, resembling those of humans with systemic lupus erythematosus (SLE). All strains show B-cell hyperactivity, autoantibodies, circulating immune complexes (IC), abnormalities in Ig and complement, extensive thymic cortical atrophy, and severe IC-type glomerulonephritis with retroviral gp70 deposits. The major differences among the strains are the amounts and specificities of autoantibodies, age of onset, disease progression, sex incidence, evidence of arteritis, and extent of lymphoid hyperplasia. The study also reports on various serologic and histopathological findings, including elevated levels of IgG and IgM, the presence of anti-nuclear antibodies (ANA), anti-dsDNA and anti-ssDNA antibodies, and the presence of cryoglobulins. The study highlights the similarities in the immunopathological features of these murine strains, suggesting that they may represent a single disease with common underlying mechanisms. The findings indicate that these mice can serve as valuable models for studying SLE, as they exhibit many of the same clinical and immunological features as humans with SLE. The study also discusses the role of retroviral gp70 in the pathogenesis of murine lupus, noting that while it is present in all strains, its exact role remains unclear. Overall, the study provides important insights into the pathogenesis of SLE in mice and highlights the potential of these models for further research into the disease.This study examines the clinical and immunopathological features of spontaneous lupus-like syndromes in several murine strains, including NZB × W, MRL/l, and BXSB mice. These strains exhibit similar clinical and immunopathological characteristics, resembling those of humans with systemic lupus erythematosus (SLE). All strains show B-cell hyperactivity, autoantibodies, circulating immune complexes (IC), abnormalities in Ig and complement, extensive thymic cortical atrophy, and severe IC-type glomerulonephritis with retroviral gp70 deposits. The major differences among the strains are the amounts and specificities of autoantibodies, age of onset, disease progression, sex incidence, evidence of arteritis, and extent of lymphoid hyperplasia. The study also reports on various serologic and histopathological findings, including elevated levels of IgG and IgM, the presence of anti-nuclear antibodies (ANA), anti-dsDNA and anti-ssDNA antibodies, and the presence of cryoglobulins. The study highlights the similarities in the immunopathological features of these murine strains, suggesting that they may represent a single disease with common underlying mechanisms. The findings indicate that these mice can serve as valuable models for studying SLE, as they exhibit many of the same clinical and immunological features as humans with SLE. The study also discusses the role of retroviral gp70 in the pathogenesis of murine lupus, noting that while it is present in all strains, its exact role remains unclear. Overall, the study provides important insights into the pathogenesis of SLE in mice and highlights the potential of these models for further research into the disease.