Interleukin-6 (B-cell stimulatory factor 2)-dependent growth of a Lennert's lymphoma-derived T-cell line (KT-3)

Abstract

A T lymphoma cell line (KT-3) established from a patient with Lennert's lymphoma showed macrophage-dependent growth. Macrophage-derived factors were able to replace the macrophage functions. Experiments using a variety of cytokines demonstrated that KT-3 proliferated in response to recombinant interleukin-2 (rIL-2), rIL-4, or rIL-6 but did not proliferate in response to rIL-1α, rIL-1β, rIL-3, recombinant granulocyte colony-stimulating factor (rG-CSF), rGM-CSF, recombinant interferon-α (rIFN-α), rIFN-γ, recombinant tumor necrosis factor (rTNF-α), or native IFN-β. Polyclonal rabbit anti-IL-6 antibody almost completely neutralized the activities of macrophage-derived factors or IL-6 but not IL-2 or IL-4. Scatchard plot analysis demonstrated that KT-3 cells indeed express IL-6 receptors. The results indicate that the macrophage-derived factor that supports the growth of KT-3 is IL-6 and suggest that macrophage-derived IL-6 may play an important role in the histopathogenesis of Lennert's lymphoma.