The Expression Pattern of Cytokine Genes and Cytokine Receptors by Hodgkin’s Disease-Derived Cell Lines HDLM-2 and KM-H2 Resembles That of Activated T Cells

Abstract

Hodgkin’s disease (HD) is a malignant disease morphologically characterized by the presence of multinucleated Reed-Sternberg (RS) and mononuclear Hodgkin’s cells (H) in a stromal background consisting of lymphocytes, plasma cells, histiocytic cells, and eosinophils. Both the etiology of HD and the precursor identity of its presumed malignant component, the RS and H cells, have remained uncertain. Various cell types have been proposed as the originator of HD, including lymphoid cells, mononuclear phagocytes, interdigitating reticulum cells, follicular dentritic cells, and granulopoietic cells. Unfortunately, the analysis of RS-H cells is hampered by the scarcity of this neoplastic component and contamination with bystander cells in HD-involved tissues. Recently, a number of cell lines have been established from tissues or pleural effusions of patients with HD, mostly of the nodular sclerosis variant. These in vitro cultured cells presumably represent the in vivo RS-H cells, as they have identical or very similar characteristic features. They might therefore be operationally regarded as in vitro representatives of RS-H cells. A number of features of HD are consistent with those of a tumor of cytokine-producing cells, including occurrence of B symptoms, sclerosis, eosinophilia, and polykaryon formation. The present study thus aimed at evaluating the spectrum of cytokines released by the two well-defined HD-derived permanent cell lines HDLM-2 [1] and KM-H2 [2]. A broad panel of cytokines was analyzed at the messenger RNA (mRNA) and protein level including granulocyte-macrophage colony-stimulating factor (GM-CSF), Granulocyte (G)-CSF, macrophage (M)-CSF, interleukin1α and -1β (IL-lα, -1β), IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, leukemia inhibitory factor (LIF), tumor necrosis factor alpha (TNF-α), TNF-β, transforming growth factor beta (TGF-β), interferon gamma (IFN-γ), monocyte chemoattractant and activating factor/JE (MCAF/JE), and the early response genes c-jun and c-fos, known to be involved in cytokine signaling. In addition, expression of the p55 and p75 IL-2 receptor chains, of the p80 IL-6 receptor, and of the M-CSF receptor (c-fms) was assessed by Northern blotting using specific complementary DNA (cDNA) probes. The presence of transcription factors known to bind to consensus sequences in regulatory 5’ flanking regions of many cytokine genes [3] such as the activation protein 1 (AP 1), the nuclear factor kappa B (NFκB), as well as the nuclear factor in activated T cells 1 (NFAT 1), previously shown to be a T-cell specific molecule [4], were analyzed in nuclear extracts of both cell lines, of T cells, and of monocytes by electrophoretic mobility shift assay (EMSA).