INTERLEUKIN-6 (B-CELL STIMULATORY FACTOR 2)-DEPENDENT GROWTH OF A LENNERT 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 repalce 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-1.alpha., rIL-1.beta., rIL-3, recombinant granulocyte colony-stimulating factor (rG-CNS), rGM-CSF, recombinant interferon .alpha.-(rIFN-.alpha.), rIFN-.gamma., recombinant tumor necrosis factor (rTNF-.alpha.), or native IFN-.beta.. 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.