Background/Purpose: To evaluate clinical associations of our recently discovered systemic sclerosis-specific auto-antigen BICD2 in clinically well characterized systemic sclerosis (SSc) cohorts from two tertiary referral centers.

Methods: Serum samples were obtained from the biobanks of the Department of Rheumatology, University Hospital Zurich, Zurich, Switzerland, and Department of Dermatology, University of Cologne, Cologne. The analysis included samples collected from patients suffering from SSc (n=302) systemic lupus erythematosus (n=39), Sjogren’s syndrome (n=11), rheumatoid arthritis (n=20), myositis (n=20) and healthy volunteers (n=99). Clinical annotation data, including age, gender, disease duration, MRSS, detailed information on organ involvement making up to a total of either >50 or >100 clinical data points (depending on the site) was available for more than 80% of all SSc serum samples included in this study. All samples were analyzed on the novel Multilisa BICD2 (CE), an ELISA for the semi-quantitative detection of anti-BICD2 antibodies in human serum or plasma.

Results: We found anti-BICD2 with a prevalence of 28% and 32% in the groups of SSc patients of the respective cohort, and only in 4.2% in cohorts with other rheumatic diseases or healthy controls (OR=8.702). Anti-BICD2 autoantibodies were present in a subgroup of SSc patients where skin fibrosis was either from the limited cutaneous subtype (p=0.0002) or restricted to sclerodactyly (p=0.0037). Within this line, anti-BICD2 autoantibodies showed a significantly higher titer in patients with moderate skin involvement reflected by low MRSS-stages (p=0.001). Analysis of pulmonary involvement revealed elevated anti-BICD2 titers in the group of patients not suffering from lung fibrosis measured by high resolution computer tomography (HCRT) (p=0.0001). Of note, the highest a-BICD2 values were observed in the group of patients having a residual transfer capability of 61-80% (DLCO stage 1 of 4). Anti-BICD2 autoantibodies were also found to be more prominent in the group of patients having a disease duration of more than 3 years.

Conclusion: In this study, we were able to further confirm the diagnostic value and high specificity of the newly discovered BICD2 autoantigen. Anti-BICD2 autoantibodies were found to be elevated in patients suffering from limited SSc, and anti-BICD2 reactivity was found to be related to clinical observations of a moderate course of disease.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-novel-anti-bicd2-autoantibody-potentially-predicts-a-favorable-disease-course-in-ssc/