Background/Purpose: Anti-ribosomal P proteins antibody (anti-rib P) is a highly specific marker for systemic lupus erythematosus (SLE) and it is associated with liver involvement in this disease. Similarities between autoimmune hepatitis (AIH) and SLE-associated hepatitis raised the possibility that anti-rib P antibodies may also have relevance in AIH. This study was therefore undertaken to evaluate the frequency and clinical significance of anti-rib P antibodies in a large AIH cohort before treatment.

Methods: Ninety-six patients with AIH diagnosed according to the Revised Original Pretreatment Scoring System of the International Autoimmune Hepatitis Group were studied. Charts were reviewed for demographic, clinical, treatment and laboratorial parameters. 82 healthy individuals were included as control. Available frozen sera samples from AIH patients obtained at diagnosis were tested for IgG anti-rib P by ELISA using a commercial kit employing synthetic 22 amino acid C-terminal peptide as antigen and reactivity was confirmed by immunoblotting using rat liver ribosomal fraction. All sera were screened for other lupus specific autoantibodies, anti-dsDNA and anti-Sm. Three patients positive for anti-dsDNA (n=1) and anti-Sm (n=2) were excluded.

Results: Moderate to high titers (>40U) of anti-rib P antibody were found in 9.7% (9/93) AIH patients and in none of the controls (p=0.003). Mean antibody titer was 93.6 ± 33.1 units. Positive results by ELISA were confirmed by immunoblotting. Patients with positive results for anti-rib P were referred to the Rheumatology Outpatient Clinic for a more detailed clinical evaluation. No sign of lupus was found in all of them. At presentation, AIH patients with and without anti-rib P antibodies had similar demographic/clinical features, including the frequency of cirrhosis (44% vs. 28%, p=0.44), hepatic laboratorial findings (p>0.05), corticosteroid and azathioprine therapy frequencies (100% vs. 99%, p=0.17 and 78% vs. 92%, p=0.17, respectively). The long follow up period was also comparable in those with and without anti-rib P antibodies (10.7± 5.1 vs. 10.3 ± 5.2 years, p=0.68). Importantly, at the final observation AIH patients with anti-rib P had a significantly higher frequency of cirrhosis compared to negative group (100% vs. 60%, p=0.04) despite no difference in the frequency of drugs at the last visit (p>0.05).

 Conclusion: The novel demonstration of anti-rib P in AIH patients without clinical and laboratorial evidence of SLE suggests a common underlying mechanism targeting liver in these two diseases. In addition, this antibody seems to predict a group of patients with worse AIH prognosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-ribosomal-p-antibodies-in-a-large-cohort-of-autoimmune-hepatitis-with-no-evidence-of-lupus-a-common-underlying-mechanism-targeting-liver/