A lymphocytotoxic factor(s) in plasma of patients with minimal change nephrotic syndrome: partial characterization

The incidence, relationship to clinical disease, and physical characteristics of a plasma cytotoxic factor(s) were studied in steroid-responsive minimal change nephrotic syndrome (MCNS) and other renal diseases. Plasma activity was found in 76% of 67 children with MCNS and in 67% of 9 children with focal segmental sclerosis (FSS). Of 31 normal adults and children and 7 adults with membranous glomerulonephritis, only 1 individual had toxic plasma. In MCNS, degree of plasma activity was not related to clinical disease, prednisone dosage, or serum levels of IgG or alpha-2-macroglobulin. The active factor(s) was found more frequently in plasma than in serum, was heat stable and nondialyzable by selected filtration, and was approximately 100,000 to 300,000 molecular weight. By DEAE column chromatography, activity coincided with fractions containing IgA and IgM but not IgG. While the nature of the plasma factor(s) has not been identified, these data indicate that MCNS plasma may adversely affect lymphocyte viability by a slow process of cytotoxicity requiring 24 or more hr, and that such plasma activity occurs frequently in children with MCNS and also with the more severe FSS.