A subset of systemic sclerosis but not of systemic lupus erythematosus is defined by isolated anti-Ku autoantibodies

CER6491
2013 Vol.31, N°2 ,Suppl.76
PI 0118, PF 0121
Diagnosis

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PMID: 23910615 [PubMed]

Received: 25/03/2013
Accepted : 21/06/2013
In Press: 23/07/2013
Published: 23/07/2013

Abstract

OBJECTIVES:
We aimed to analyse the annual incidence of anti-Ku antibodies and to study their clinical associations in patients mainly affected by systemic sclerosis (SSc) and systemic lupus erythematosus (SLE) overlap diseases.
METHODS:
Anti-Ku were detected by counterimmunoelectrophoresis in a total of 203 sera during 14 years of anti-ENA detection. Anti-Ku+ sera belong to 46 patients, mostly affected by UCTD (12 cases), SSc spectrum diseases (13 cases), including SSc/PM, SSc/DM and SSc; and SLE spectrum diseases (9 cases), including SLE, SLE/APS, SLE/SS, SLE/PM.
RESULTS:
Anti-Ku antibodies represent 2% of all anti-ENA positive sera, and are found in 1.3-3% of anti-ENA positive sera per year. Anti-Ku+ SSc represents 2% of all SSc patients. All anti-Ku+ SSc spectrum diseases showed a limited cutaneous disease; myositis, dysphagia and isolated anti-Ku in more than 70% of cases. Interstitial lung disease (ILD) was found in 54% of SSc patients, frequently with mild functional impairment. When compared with other limited SSc cases, anti-Ku+ SSc showed a higher rate of male patients, arthritis, myositis and ILD. A lower rate of digital ulcers was found, although both groups showed the same rate of SSc pattern at nailfold capillaroscopy. Anti-Ku+ SLE patients (representing 1.5% of all SLE) showed cutaneous features, Raynaud`s phenomenon, multiple autoantibodies, without major organ manifestations. Isolated anti-Ku+ patients significantly show a diagnosis within SSc spectrum diseases, with arthralgias, Raynaud`s phenomenon, dysphagia, ILD, myositis and sclerodactyly.
CONCLUSIONS:
In SLE spectrum diseases, anti-Ku are found associated with other autoantibodies, without a peculiar clinical profile, except for Raynaud`s phenomenon and severe alterations of capillary bed. In SSc anti-Ku are frequently associated with myositis and ILD, mostly found as isolated autoantibodies.