Autoantibody to scaffold attachment factor B (SAFB): A novel connective tissue disease-related autoantibody associated with interstitial lung disease.
To identify and characterize a novel connective tissue disease (CTD)-related autoantibody (autoAb) directed against scaffold attachment factor B (SAFB).



AutoAb specificity was analyzed using RNA and protein-immunoprecipitation assays. Autoimmune targets were affinity purified using patients' sera and subjected to liquid chromatography mass spectrometry.



By immunoprecipitation assay, 10 sera reacted with a protein with a molecular weight of approximately 160 kDa. Liquid chromatography mass spectrometry of the partially purified autoantigen and additional immunoblot-based analyses revealed that the Ab specifically recognized SAFB. Anti-SAFB Abs were detected in 2 of 646 patients with systemic sclerosis (SSc) (0.3%), 1 of 1570 patients with polymyositis/dermatomyositis (0.06%), 4 of 270 patients with interstitial lung disease (ILD) (1.5%), 1 of 43 patients with overlap syndrome (2.3%) and 2 patients with other diseases including primary Raynaud's disease and eosinophilic pneumonia. Five patients with anti-SAFB Abs had Raynaud's phenomenon and 3 had nail fold punctate hemorrhage. Of note, 8 of the 10 patients (80%) suffered from ILD. None of the patients with anti-SAFB Abs had pulmonary arterial hypertension, heart disease, or renal involvement.



Anti-SAFB Ab is a novel CTD-related autoAb possibly associated with ILD.
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
Akiko
A
Takeuchi
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
Takashi
T
Matsushita
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
Kenzo
K
Kaji
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
Yoshinobu
Y
Okamoto
Division of Respiratory Medicine, Department of Internal Medicine, Kanazawa Municipal Hospital, Kanazawa, Japan.
Masahide
M
Yasui
Division of Rheumatology, Department of Internal Medicine, Takaoka Municipal Hospital, Takaoka, Japan.
Masayoshi
M
Hirata
Department of Dermatology, Kurobe Municipal Hospital, Kurobe, Japan.
Naoto
N
Oishi
Department of Dermatology, Toyama Red Cross Hospital, Toyama, Japan.
Akira
A
Higashi
Department of Dermatology, Gifu University, Gifu, Japan.
Mariko
M
Seishima
Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Kanazawa, Japan.
Tomoya
T
Asano
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan; Department of Dermatology, University of Tsukuba, Tsukuba, Japan.
Manabu
M
Fujimoto
Department of Allergy and Rheumatology, Nippon Medical School Graduate School of Medicine, Tokyo, Japan.
Masataka
M
Kuwana
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
Kazuhiko
K
Takehara
Department of Dermatology, Faculty of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan. Electronic address: yasuhito@med.kanazawa-u.ac.jp.
Yasuhito
Y
Hamaguchi
D000368:Aged; D001323:Autoantibodies / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology*; D015415:Biomarkers; D016022:Case-Control Studies; D003240:Connective Tissue Diseases / Q000175:diagnosis / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis / Q000276:immunology*; D008297:Male; D036961:Matrix Attachment Region Binding Proteins / Q000276:immunology*; D008875:Middle Aged; D034521:Nuclear Matrix-Associated Proteins / Q000276:immunology*; D010641:Phenotype; D011960:Receptors, Estrogen / Q000276:immunology*
D001323:Autoantibodies; D001324:Autoantigens; D015415:Biomarkers; D036961:Matrix Attachment Region Binding Proteins; D034521:Nuclear Matrix-Associated Proteins; D011960:Receptors, Estrogen; C109132:SAFB protein, human
Anti-SAFB Ab; Anti-nuclear Ab; Interstitial lung disease; Raynaud's phenomenon