Clinical, biological and pharmacological keynotes

Auto-antibodies in autoimmune hepatitis: Anti-soluble liver antigen (SLA)

Detection of anti-soluble liver antigen (SLA) antibodies

Anti-SLA antibodies cannot be revealed by indirect immunofluorescence on a common substrate but are detectable using radioimmunoassay, enzyme linked immunosorbent assays (Elisa), immunoblotting and dot blotting using native cytosolic antigen or recombinant 50 kDa protein identified as the UGA serine tRNA-protein complex [4], [5], [6] and, more recently, as o-phosphoseryl-tRNA: selenocysteinyl-tRNA synthase (SepSecS) [7]. In 2010, this identification of recombinant protein was confirmed by mass

Anti-soluble liver antigen (SLA) has been considered as a specific diagnostic marker of autoimmune hepatitis type 1 (AIH-1)

The frequency of anti-SLA in AIH-1 has been reported as being between 6% and 58% in adults and children [1], [4], [9], [10], [11], [12], [13], [14], [15], [16], [17], alone or in combination with ASMA and/or ANA. The lowest prevalence was found in patients from Japan [12], [13]. These antibodies have also been described in 15% to 30% of PBC/AIH overlap syndrome [4], [16]. However, their detection is particularly useful in patients without conventional antibodies, and they have enabled the

Prognostic value of anti-soluble liver antigen (SLA)

The prognostic value of antibodies to SLA has seldom been studied and remains controversial [14], [15], [16], [21]. Ma et al. [14] suggested that anti-SLA reactivity against conformational epitopes identified patients with a worse prognosis. However, their patients were children in whom the presentation and course of the disease were more severe than in adults.

An association between AIH recurrence after liver transplantation and antibodies to SLA has also been described (anti-SLA prevalence of

Anti-soluble liver antigen (SLA) and response to treatment

Previous studies in AIH-1 patients indicated that individuals with and without anti-SLA were similar in terms of their initial response to corticosteroid therapy [11], [15], [16], [21], [23]. It has been also shown that anti-SLA persist during the disease and its treatment [24]. However, seropositivity was associated with a higher frequency of relapse after corticosteroid withdrawal: the relapse rate among anti-SLA-positive patients in several studies was 14/14 (100%) compared with 74/102 (73%)

Anti-soluble liver antigen (SLA) in aetiopathogenesis of autoimmune hepatitis

Because anti-SLA have a high degree of specificity for AIH, are directed against a single antigen and are associated with relapse after corticosteroid withdrawal, they may reflect a pertinent pathogenic process more strongly than either ASMA or ANA [24]. Their association with DRB1*0301 may influence disease occurrence and severity by affecting auto-antigen presentation and/or by synergizing with other autoimmune promoters [24].

Concerning the structure of the antigen, SLA has sequence homology

Conclusion

In summary, antibodies to SLA are of major diagnostic value for AIH-1, including paediatric forms and overlap syndromes with cholestatic diseases. Their detection is particularly useful in patients who are negative for conventional markers of the disease (ANA, ASMA). The prognostic value of anti-SLA is controversial but they could be used to evaluate the risk of relapse of the inflammatory process after corticosteroid therapy and the recurrence of autoimmune hepatitis after orthotopic liver

Disclosure of interest

The authors declare that they have no conflicts of interest concerning this article.