Shuichiro Nakabo1,2, Hajime Yoshifuji1,2, Motomu Hashimoto1,2, Yoshitaka Imura1,2, Ran Nakashima1,2, Kosaku Murakami1,2, Nobuo Kuramoto1,2, Shinji Ito1,2, Junko Satoh1,2, Masao Tanaka1,2, Takao Fujii1,2, Tsuneyo Mimori1,2, Koichiro Ohmura3,4. 1. From the Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto; Department of Clinical Immunology and Rheumatology, Wakayama Medical University, Wakayama, Japan. 2. S. Nakabo, MD, research fellow, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; H. Yoshifuji, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; M. Hashimoto, MD, PhD, Assistant professor, Department of the Control for Rheumatic Diseases, Graduate School of Medicine, Kyoto University; Y. Imura, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; R. Nakashima, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; K. Murakami, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; N. Kuramoto, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; S. Ito, PhD, Assistant professor, Medical Research Support Center, Graduate School of Medicine, Kyoto University; J. Satoh, PhD, Postdoctoral fellow, Medical Research Support Center, Graduate School of Medicine, Kyoto University; M. Tanaka, MD, PhD, Associate professor, Department of the Control for Rheumatic Diseases, Graduate School of Medicine, Kyoto University; T. Fujii, MD, PhD, Professor, Department of Clinical Immunology and Rheumatology, Wakayama Medical University, and Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; T. Mimori, MD, PhD, Professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; K. Ohmura, MD, PhD, Associate professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University. 3. From the Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, Kyoto; Department of Clinical Immunology and Rheumatology, Wakayama Medical University, Wakayama, Japan. ohmurako@kuhp.kyoto-u.ac.jp. 4. S. Nakabo, MD, research fellow, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; H. Yoshifuji, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; M. Hashimoto, MD, PhD, Assistant professor, Department of the Control for Rheumatic Diseases, Graduate School of Medicine, Kyoto University; Y. Imura, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; R. Nakashima, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; K. Murakami, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; N. Kuramoto, MD, PhD, Assistant professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; S. Ito, PhD, Assistant professor, Medical Research Support Center, Graduate School of Medicine, Kyoto University; J. Satoh, PhD, Postdoctoral fellow, Medical Research Support Center, Graduate School of Medicine, Kyoto University; M. Tanaka, MD, PhD, Associate professor, Department of the Control for Rheumatic Diseases, Graduate School of Medicine, Kyoto University; T. Fujii, MD, PhD, Professor, Department of Clinical Immunology and Rheumatology, Wakayama Medical University, and Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; T. Mimori, MD, PhD, Professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University; K. Ohmura, MD, PhD, Associate professor, Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University. ohmurako@kuhp.kyoto-u.ac.jp.
Abstract
OBJECTIVE: Anti-carbamylated protein (anti-CarP) antibodies are possible diagnostic biomarkers of anticitrullinated protein antibody (ACPA)-negative rheumatoid arthritis (RA). We aimed to elucidate the prevalence of anti-CarP antibodies in non-RA connective tissue diseases (CTD) because CTD are important in the differential diagnosis of ACPA-negative RA. METHODS: The sera from 266 patients with RA and 616 patients with CTD and 80 healthy controls were examined using an in-house anti-CarP ELISA. RESULTS: The prevalence and the level of anti-CarP antibodies in several CTD were comparable to those in ACPA-negative RA. CONCLUSION: Anti-CarP antibodies are not useful for differentiating ACPA-negative RA from CTD.
OBJECTIVE: Anti-carbamylated protein (anti-CarP) antibodies are possible diagnostic biomarkers of anticitrullinated protein antibody (ACPA)-negative rheumatoid arthritis (RA). We aimed to elucidate the prevalence of anti-CarP antibodies in non-RA connective tissue diseases (CTD) because CTD are important in the differential diagnosis of ACPA-negative RA. METHODS: The sera from 266 patients with RA and 616 patients with CTD and 80 healthy controls were examined using an in-house anti-CarP ELISA. RESULTS: The prevalence and the level of anti-CarP antibodies in several CTD were comparable to those in ACPA-negative RA. CONCLUSION: Anti-CarP antibodies are not useful for differentiating ACPA-negative RA from CTD.