Fingerprinting of anti-alpha enolase antibodies in systemic sclerosis.

Objectives: Anti-alpha enolase antibodies have been detected in systemic sclerosis (SSc), but little is known on their fine specificity and their predictive value on single disease manifestations. The aim of this work is to perform an epitope mapping of alpha enolase by means of truncated recombinant proteins and to analyse the clinico-serological correlations of anti-alpha enolase antibodies in SSc patients. Methods: Thirty-eight SSc patients were recruited and fully clinically and serologically characterised. Plasmids encoding full length and truncated polypeptides of alpha enolase were generated; the polypeptides were purified under native conditions and used in dot blot to test sera from SSc patients and controls. The densitometric values obtained on all the polypeptides with anti-IgG subclass specific antibodies were analysed by cluster analysis and partial least square regression. Results: Anti-alpha enolase antibodies (mostly IgG1 and IgG2) are detected in 47% of SSc patients. IgG1 target the amino terminal region of alpha enolase, while IgG2 are more restricted to the central portion of the molecule. Anti-alpha enolase antibodies are not associated with disease-specific antibodies or with interstitial lung disease and do not identify patients affected by the limited vs. diffuse form. Conclusions: Anti-alpha enolase antibodies are very frequent in SSc but are not associated with clinical or serological features of the disease. Further studies on larger cohorts of patients are necessary to define their possible contribution in defining specific subsets of the disease.