title: The interleukin-6 receptor alpha-chain (CD126) is expressed by neoplastic but not normal plasma cells.
abstract: Interleukin-6 (IL-6) is reported to be central to the pathogenesis of myeloma, inducing proliferation and inhibiting apoptosis in neoplastic plasma cells. Therefore, abrogating IL-6 signaling is of therapeutic interest, particularly with the development of humanized anti-IL-6 receptor (IL-6R) antibodies. The use of such antibodies clinically requires an understanding of IL-6R expression on neoplastic cells, particularly in the cycling fraction. IL-6R expression levels were determined on plasma cells from patients with myeloma (n = 93) and with monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma (n = 66) and compared with the levels found on normal plasma cells (n = 11). In addition, 4-color flow cytometry was used to assess the differential expression by stage of differentiation and cell cycle status of the neoplastic plasma cells. IL-6R alpha chain (CD126) was not detectable in normal plasma cells, but was expressed in approximately 90% of patients with myeloma. In all groups, the expression levels showed a normal distribution. In patients with MGUS or plasmacytoma, neoplastic plasma cells expressed significantly higher levels of CD126 compared with phenotypically normal plasma cells from the same marrow. VLA-5(-) "immature" plasma cells showed the highest levels of CD126 expression, but "mature" VLA-5(+) myeloma plasma cells also overexpressed CD126 when compared with normal subjects. This study demonstrates that CD126 expression is restricted to neoplastic plasma cells, with little or no detectable expression by normal cells. Stromal cells in the bone marrow microenvironment do not induce the overexpression because neoplastic cells express higher levels of CD126 than normal plasma cells from the same bone marrow in individuals with MGUS. (Blood. 2000;96:3880-3886)
authors.affiliation: Haematological Malignancy Diagnostic Service, Department of Haematology, Leeds General Infirmary, Leeds, United Kingdom.
authors.forename: A C
authors.initials: AC
authors.lastname: Rawstron
authors.forename: J A
authors.initials: JA
authors.lastname: Fenton
authors.forename: J
authors.initials: J
authors.lastname: Ashcroft
authors.forename: A
authors.initials: A
authors.lastname: English
authors.forename: R A
authors.initials: RA
authors.lastname: Jones
authors.forename: S J
authors.initials: SJ
authors.lastname: Richards
authors.forename: G
authors.initials: G
authors.lastname: Pratt
authors.forename: R
authors.initials: R
authors.lastname: Owen
authors.forename: F E
authors.initials: FE
authors.lastname: Davies
authors.forename: J A
authors.initials: JA
authors.lastname: Child
authors.forename: A S
authors.initials: AS
authors.lastname: Jack
authors.forename: G
authors.initials: G
authors.lastname: Morgan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015703:Antigens, CD / Q000096:biosynthesis / Q000276:immunology; D000951:Antigens, Neoplasm / Q000096:biosynthesis; D015415:Biomarkers; D014408:Biomarkers, Tumor; D001854:Bone Marrow Cells / Q000737:chemistry / Q000276:immunology; D019046:Bone Marrow Neoplasms / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D050822:Cytokine Receptor gp130; D005434:Flow Cytometry; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000276:immunology; D008875:Middle Aged; D009101:Multiple Myeloma / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis; D010265:Paraproteinemias / Q000378:metabolism; D010950:Plasma Cells / Q000737:chemistry / Q000276:immunology; D010954:Plasmacytoma / Q000737:chemistry* / Q000276:immunology; D021122:Protein Subunits; D017469:Receptors, Fibronectin / Q000032:analysis; D019947:Receptors, Interleukin-6 / Q000096:biosynthesis* / Q000276:immunology; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D015703:Antigens, CD; D000951:Antigens, Neoplasm; D015415:Biomarkers; D014408:Biomarkers, Tumor; C494199:IL6ST protein, human; D019394:Ki-67 Antigen; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D021122:Protein Subunits; D017469:Receptors, Fibronectin; D019947:Receptors, Interleukin-6; D001613:beta 2-Microglobulin; D050822:Cytokine Receptor gp130