Immunopathologic Studies of Systemic Lupus Erythema - tosus . II

The yG-globulin eluted at acid pH from kidney cortex homogenates and isolated glomeruli of five of six patients with lupus nephritis was found to exhibit antinuclear activity, which was not dependent on presence of fresh human serum. Specificity, as demonstrated by absorption of antinuclear activity, was related to nucleoprotein in three glomerular acid eluates and to DNA in two acid eluates as well as in a deoxyribonuclease digest of disrupted glomeruli in one patient. Antinuclear activity was not found in acid eluates of kidneys from two patients with chronic liver disease and chronic discoid lupus, respectively, and one with lupus nephritis. These patients had a low titer of serum antinuclear factor and lesser amounts of kidney bound immunoglobulins. The presence of antinuclear activity in eluates of kidneys appeared to correlate with the amount of glomerular bound immunoglobulin and the level of antinuclear antibodies in serum. These findings suggest that in lupus nephritis, part of the glomerular bound immunoglobulin is derived from serum antinuclear factors possibly deposited as immune complexes.