Myositis-specific and myositis-associated antibodies in a series of eighty-eight Mediterranean patients with idiopathic inflammatory myopathy.
OBJECTIVE
To determine the prevalence of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) and their clinical and immunogenetic correlations in Mediterranean patients with idiopathic inflammatory myopathies.


METHODS
Sera from 88 patients were studied for MSAs and MAAs by RNA and protein immunoprecipitation. HLA typing was performed by sequence-specific primer- and sequence-specific oligonucleotide-polymerase chain reaction and serology. Statistical analyses were performed with Student's t-test and Fisher's exact test. Cumulative survival probabilities were estimated by the Kaplan-Meier method and Cox regression analysis.


RESULTS
Twenty-eight patients (30%) had MSAs, most commonly antisynthetase antibodies (23.9%). Six patients (7.5%) had anti-Mi-2 antibodies. No anti-signal recognition particles were found. Arthritis, mechanic's hands, interstitial lung disease, and sicca syndrome were more prevalent in patients with antisynthetase antibodies. Dysphagia and the need for more treatment courses were more frequent in patients who were anti-Mi-2 positive. Forty-three patients (48%) had MAAs, 20 (22%) with anti-Ro 60 and 18 (20.4%) with anti-Ro 52. Ten patients (11.4%) were positive for anti-PM-Scl, 6 (6.8%) for anti-RNP, and 1 for anti-Ku antibodies. Patients with PM-Scl, RNP, or Ro antibodies were more often classified as having overlap syndrome. Immunogenetic studies found a significant association between HLA-DR3 and the presence of antisynthetase antibodies (P = 0.049), anti-PM-Scl antibodies (P = 0.017), and interstitial lung disease (P = 0.03). No statistically significant differences in mortality, survival, or clinical course were observed between patients positive for MSAs or MAAs and the remaining patients.


CONCLUSIONS
These results are consistent with those from other published series, although some differences warrant consideration. Autoantibody studies may be useful for defining more homogeneous groups of patients with idiopathic inflammatory myopathies.
Selva-O'Callaghan
Albert
A
Vall D'Hebron General Hospital, Universitat Autonoma de Barcelona, Barcelona, Spain. aselva@vhebron.net
Labrador-Horrillo
Moisés
M
Solans-Laque
Roser
R
Simeon-Aznar
Carmen Pilar
CP
Martínez-Gómez
Xavier
X
Vilardell-Tarrés
Miquel
M
D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D001323:Autoantibodies / Q000097:blood* / Q000235:genetics / Q000276:immunology; D005095:Exoribonucleases / Q000276:immunology; D063326:Exosome Multienzyme Ribonuclease Complex; D005260:Female; D015803:HLA-DR3 Antigen / Q000276:immunology; D006650:Histocompatibility Testing; D006801:Humans; D008025:Ligases / Q000276:immunology; D008297:Male; D019083:Mediterranean Region; D008875:Middle Aged; D009220:Myositis / Q000097:blood* / Q000276:immunology* / Q000401:mortality; D009687:Nuclear Proteins / Q000276:immunology; D011379:Prognosis; D012313:RNA / Q000235:genetics; D012044:Regression Analysis; D016019:Survival Analysis
D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D015803:HLA-DR3 Antigen; C045760:Mi-2 antibodies; D009687:Nuclear Proteins; C035356:SS-A antibodies; D012313:RNA; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C077044:EXOSC10 protein, human; D008025:Ligases