title: Production of a High-affinity Monoclonal Antibody Reactive with Folate Receptors Alpha and Beta.
abstract: Folate receptors α (FRα) and β (FRβ) are two isoforms of the cell surface glycoprotein that binds folate. The expression of FRα is rare in normal cells and elevated in cancer cells. Thus, FRα-based tumor-targeted therapy has been a focus area of laboratory research and clinical trials. Recently, it was shown that a significant fraction of tumor-associated macrophages expresses FRβ and that these cells can enhance tumor growth. Although FRα and FRβ share 70% identity in their deduced amino acid sequence, a monoclonal antibody (MAb) reactive with both receptors has not been developed. A MAb that can target both FRα-expressing cancer cells and FRβ-expressing tumor-associated macrophages may provide a more potent therapeutic tool for cancer than individual anti-FRα or anti-FRβ MAbs. In this study, we developed a MAb that recognizes both FRα and FRβ (anti-FRαβ). The anti-FRαβ specifically stained trophoblasts and macrophages from human placenta, synovial macrophages from rheumatoid arthritis patient, liver macrophages from cynomolgus monkey and common marmoset, and cancer cells and tumor-associated macrophages from ovary and lung carcinomas. Surface plasmon resonance showed that the anti-FRαβ bound to soluble forms of the FRα and FRβ proteins with high affinity (KD=6.26×10(-9) M and 4.33×10(-9) M, respectively). In vitro functional analysis of the anti-FRαβ showed that this MAb mediates complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, and antibody-dependent cellular phagocytosis of FRα-expressing and FRβ-expressing cell lines. The anti-FRαβ MAb is a promising therapeutic candidate for cancers in which macrophages promote tumor progression.
authors.affiliation: 1 Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University , Kagoshima, Japan .
authors.forename: Taku
authors.initials: T
authors.lastname: Nagai
authors.affiliation: 1 Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University , Kagoshima, Japan .
authors.forename: Yuko
authors.initials: Y
authors.lastname: Furusho
authors.affiliation: 1 Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University , Kagoshima, Japan .
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: 1 Department of Immunology, Graduate School of Medical and Dental Sciences, Kagoshima University , Kagoshima, Japan .
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Hasui
authors.affiliation: 2 Department of Clinical Pathology, Kagoshima Kousei-Ren Hospital , Kagoshima, Japan .
authors.forename: Sumika
authors.initials: S
authors.lastname: Matsukita
authors.affiliation: 3 Department of Clinical Pathology, Kagoshima City Hospital , Kagoshima, Japan .
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Sueyoshi
authors.affiliation: 4 Department of Surgery, Kagoshima City Hospital , Kagoshima, Japan .
authors.forename: Masakazu
authors.initials: M
authors.lastname: Yanagi
authors.affiliation: 5 Department of Obstetrics, Kagoshima City Hospital , Kagoshima, Japan .
authors.forename: Masaki
authors.initials: M
authors.lastname: Hatae
authors.affiliation: 6 The Center for Advanced Biomedical Sciences and Swine Research, Kagoshima University , Kagoshima, Japan .
authors.forename: Sonshin
authors.initials: S
authors.lastname: Takao
authors.affiliation: 6 The Center for Advanced Biomedical Sciences and Swine Research, Kagoshima University , Kagoshima, Japan .
authors.forename: Takami
authors.initials: T
authors.lastname: Matsuyama
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology*; D000917:Antibody Formation; D000920:Antibody-Dependent Cell Cytotoxicity; D001172:Arthritis, Rheumatoid / Q000175:diagnosis* / Q000276:immunology; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D058975:Folate Receptor 1 / Q000276:immunology*; D058976:Folate Receptor 2 / Q000276:immunology*; D006801:Humans; D007124:Immunoenzyme Techniques; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000276:immunology; D008252:Macaca fascicularis; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000276:immunology; D010920:Placenta / Q000276:immunology; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D020349:Surface Plasmon Resonance; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014327:Trophoblasts / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D058975:Folate Receptor 1; D058976:Folate Receptor 2