Human Lymphotoxin Obtained from Established Lymphoid Lines: Purification Characteristics and Inhibition by Anti-Immunoglobulin

Abstract

Human lymphotoxin obtained from established lymphoid cell lines (HLT-LCL) was studied in detail and purified using ammonium sulfate fractionation, gel filtration, ion-exchange column chromatography, and polyacrylamide gel electrophoresis. HLT-LCL is stable at 20°C for over 1 year, at 4°C for 3 weeks, and at 37°C for 1 week. HLT-LCL showed a decrease in activity at pH 2.0 and 3.0, but was stable at a pH range of 5.0–11.0 HLT-LCL, which contained fetal calf serum, was purified 50-fold. HLT-LCL obtained from serum-free culture medium yielded greater purity, although complete purification was not achieved. Antiserum to HLT-LCL neutralized the cytotoxic activity of HLT-LCL, HLT induced by PHA (HLT-PHA), and HLT induced by PPD (HLT-PPD). Antiserum to human IgG, λ-type L chain, and Fc fragment partially but significantly inhibited HLT-LCL activity. These data, together with previous reports, indicate that the HLT-LCL molecule is immunologically similar to HLT-PHA and HLT-PPD and suggest that there is immunologic cross-reactivity with IgG globulin.