Résumé
Axial spondyloarthritis (axSpA) is a common chronic inflammatory rheumatic disease. Despite the advent of MRI, the diagnostic delay for axSpA remains often long. In an effort to refine the diagnosis of axSpA, several autoantibodies with varying metrological qualities have been identified. Among them, anti-CD74 autoantibodies (a chaperone molecule and HLA class II targeting molecule) have recently garnered interest, with contradictory data [1]. To date, the seroprevalence, diagnostic metrological properties, and prognostic value of anti-CD74 antibodies have not been evaluated in a large cohort of axSpA patients. Furthermore, the role of the natural ligand of CD74, the cytokine “Macrophage Migration Inhibitory Factor” (MIF), has also not been assessed in this context.
The aim of our study was to evaluate the interest of measuring anti-CD74 antibodies and MIF for the diagnosis, the phenotypic characterization, and the prognosis of axSpA.
We analyzed the clinical, biological, serological (anti-CD74 and MIF), and radiological characteristics of all patients from the DESIR cohort (NCT01648907) [2]. The serological data were compared to those of 55 control patients from the MODI-PRP cohort, who had discogenic low back pain with MODIC 1 changes for more than 3 months, with exclusion of axSpA diagnosis. Anti-CD74 antibodies were measured by ELISA IgA Aeskulisa SpA detect, and MIF by ELISA Human MIF Quantikine ELISA Kit. For the primary objectives, we: (1) compared the seroprevalence and serum levels of anti-CD74 antibodies in axSpA patients and controls; compared serum MIF levels in axSpA patients and controls; (2) assessed the diagnostic value of anti-CD74 antibodies and MIF for diagnosing axSpA (ROC curves); (3) evaluated the concordance between ASAS criteria and the presence of anti-CD74 autoantibodies/MIF. For secondary objectives, we assessed the association of anti-CD74 antibodies and MIF (as both continuous and dichotomous variables) with axSpA characteristics at baseline and after 5 years (Student's t-test or equivalent, Spearman's test or equivalent).
The 708 patients in the DESIR cohort had a mean age at inclusion of 33.7 years (SD 8.6), with an average duration of low back pain of 1.5 years (SD 0.9). 57.2% had peripheral involvement, 16.7% had psoriasis, 9.2% had uveitis, and 4.9% had IBD. 58% were HLA-B27 positive, and the mean CRP level was 7.9 mg/L (SD 13.5). 59.7% met ASAS criteria, of which 28.9% met the imaging criterion and 31.7% met the clinical criterion. We found no significant difference in anti-CD74 concentration between axSpA patients (regardless of ASAS status) and controls. However, MIF levels were moderately and significantly lower in axSpA (Figure 1). The diagnostic value of anti-CD74 was poor, and that of MIF was insufficient, even when analyzing the subgroup of axSpA patients meeting ASAS criteria (Figure 2). The concordance between the presence of these biomarkers and ASAS criteria was not assessed due to the lack of significant differences in serum levels between groups. Finally, we found no statistically significant or clinically relevant association between the biomarkers and the clinical or radiological features of axSpA at baseline and at 5 years.
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Measuring anti-CD74 antibodies and MIF does not appear to be useful for the diagnostic, phenotypic, or prognostic evaluation of axSpA.
[1] Riechers E et al. Sensitivity and Specificity of Autoantibodies Against CD 74 in Nonradiographic Axial Spondyloarthritis. Arthritis Rheumatol 2019;71:729–35. doi:10.1002/art.4077.
[2] Dougados M et al. Joint Bone Spine. 2015 Oct;82(5):345-51. doi: 10.1016/j.jbspin.2015.02.006.
Société Française de Rhumatologie, Cohorte DESIR.
None declared.
© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.