Anti-Ku antibodies in connective tissue diseases: clinical and serological evaluation of 14 patients.
OBJECTIVE
To assess the clinical and serological associations of anti-Ku antibodies.


METHODS
Fourteen patients with anti-Ku antibody detected by counterimmunoelectrophoresis (CIE) and immunoblot (IB) were retrospectively evaluated.


RESULTS
Patients (13 women, one man) had a mean age of 60.3 years (range 19-83). Seven patients had overlap syndromes: 5 polymyositis/scleroderma (PM/SSc), one systemic lupus erythematosus (SLE)/SSc/PM, and one SLE/PM. Three additional patients had undifferentiated connective tissue disease, 2 primary Sjögren's syndrome (SS), one psoriatic arthritis, and one SSc. The clinical manifestations most frequently recorded were arthralgias (86%), myositis (50%) and Raynaud's phenomenon (78.6%). Five patients had esophageal dysmotility, while 6 showed interstitial pulmonary fibrosis (4 of them with reduced DLCO). No case of pulmonary hypertension was observed. All patients had very high titer of ANA with speckled and nucleolar pattern. All the sera were positive for anti-Ku antibodies by CIE: all but one were confirmed by IB. Eight sera contained isolated antibodies to Ku proteins: both subunits were recognized in 7 cases, while isolate reactivity to the 70 kDa protein was detected in one case. Five sera contained additional antibody specificities: anti-Ro 60 kDa in 4 cases, and anti-La/SSB, anti-SL, and anti-PM-Scl in one case each.


CONCLUSIONS
Anti-Ku antibody is found in a wide spectrum of connective tissue diseases including overlap syndromes with SSc and myositis. Raynaud's phenomenon and muscular and joint involvement are the most frequent clinical features associated with anti-Ku antibodies, which are frequently detected in association with anti-Ro/SSA and/or other antinuclear specificities.
Clinical Immunology Unit, Spedali Civili, University of Brescia, Italy. cattaneo@master.cci.unibs.it
Franco
F
Franceschini
Ilaria
I
Cavazzana
Daniele
D
Generali
Marzia
M
Quinzanini
Luigi
L
Viardi
Anna
A
Ghirardello
Andrea
A
Doria
Roberto
R
Cattaneo
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D034961:Antigens, Nuclear; D001323:Autoantibodies / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis; D003240:Connective Tissue Diseases / Q000175:diagnosis* / Q000276:immunology*; D003378:Counterimmunoelectrophoresis / Q000379:methods; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000032:analysis / Q000276:immunology*; D005069:Evaluation Studies as Topic; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; D005260:Female; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D000072200:Ku Autoantigen; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000032:analysis* / Q000276:immunology*; D017285:Polymyositis / Q000175:diagnosis / Q000276:immunology; D012189:Retrospective Studies; D012595:Scleroderma, Systemic / Q000175:diagnosis / Q000276:immunology; D012680:Sensitivity and Specificity
D034961:Antigens, Nuclear; D001323:Autoantibodies; D015415:Biomarkers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C077044:EXOSC10 protein, human; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen