Diagnostic Value of Anti-CD74 Antibodies in Early Axial Spondyloarthritis: Data from the Spondyloarthritis Caught Early (SPACE) Cohort

Janneke de Winter¹, Marleen van de Sande¹, Niklas Thomas Baerlecken², Inger Berg³, Roberta Ramonda⁴, Désirée van der Heijde⁵, Floris van Gaalen⁶, Torsten Witte⁷ and Dominique Baeten^1,8, ¹Clinical Immunology and Rheumatology, Amsterdam Rheumatology and immunology Center, Academic Medical Center/University of Amsterdam, Amsterdam, Netherlands, ²Rheumatology, Private Practice, Cologne, Germany, ³Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, ⁴Rheumatology Unit, Department of Medicine DIMED, University of Padova, Padova, Italy, ⁵Rheumatology, Leiden University Medical Center, Leiden, Netherlands, ⁶Leiden University Medical Center, Leiden, Netherlands, ⁷Clinical Immunology and Rheumatology, Medical University Hannover, Hanover, Germany, ⁸UCB Pharma, Slough, United Kingdom

Meeting: 2017 ACR/ARHP Annual Meeting

Date of first publication: September 18, 2017

Keywords: axial spondyloarthritis, diagnosis and laboratory tests, Diagnostic Tests

Session Information

Date: Sunday, November 5, 2017

Title: Spondyloarthropathies and Psoriatic Arthritis – Clinical Aspects and Treatment Poster I

Session Type: ACR Poster Session A

Session Time: 9:00AM-11:00AM

Background/Purpose:

Anti-CD74 IgG antibodies are reported to be elevated in serum of patients with axial spondyloarthritis (axSpA). This study aimed to assess the diagnostic value of anti-CD74 antibodies to discriminate between early axSpA and non-SpA in early back pain patients.

Methods:

Using ELISA, we first confirmed the elevation of anti-CD74 IgG and IgA serum antibodies in patients with radiographic axSpA (ankylosing spondyloarthritis, (AS)) (n=138) when compared to healthy controls (n=57). Next, we tested their diagnostic value in patients with early axSpA (n=274) and non-SpA back pain controls (n=319) from the SPondyloArthritis Caught Early (SPACE) cohort.

Results:

Median anti-CD74 IgG antibodies (OD) were higher in AS patients than in healthy controls (0.70 vs. 0.51, p<.0001) and present in 79.7% of AS patients vs. 43.9% of healthy controls (p<0.0001). Anti-CD74 IgG antibody levels (OD) did not differ between axSpA patients and non-SpA back pain controls (0.50 vs. 0.52, p=0.152) and were present in 46.4% of the axSpA patients vs. 47.9% of the non-SpA back pain controls (p=0.713). Median anti-CD74 IgA antibodies (OD) were higher in AS patients than in healthy controls (0.31 vs. 0.20, p<0.0001) and present in 28.5% of AS patients vs. 5.3% of healthy controls (p<0.0001). In the SPACE cohort, anti-CD74 IgA antibodies (U/mL) were higher in axSpA patients than in non-SpA back pain controls (19.92 vs. 14.02, p<0.0001) and present in in 54.7% vs. 37.0% of the axSpA patients vs. non-SpA back pain controls (p<0.0001), respectively. This resulted in a PPV of 58.8% and a NPV of 59.1%. In a multivariate logistic regression model including anti-CD74 IgA and total serum IgA, total serum IgA was associated with a diagnosis of axSpA (Exp(B) 1.19, p<0.0001) whereas anti-CD74 IgA was not (Exp(B) 1.01, p=0.332).

Conclusion:

Anti-CD74 IgG and anti-CD74 IgA were elevated in AS versus healthy controls. Only anti-CD74 IgA is elevated in patients with early axSpA versus chronic back pain controls of the SPACE cohort. In the SPACE cohort, these differences disappear in a multivariate analysis with total IgA levels and have limited diagnostic value in these early back pain patients. Other biomarker or biological features of anti-CD74 IgA, including prediction/contribution to radiographic progression, should be investigated.

Disclosure: J. de Winter, None; M. van de Sande, Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 8,Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 2,Takeda, Tillots, MSD, Abbvie,novartis, boeringer ingelheim, 5; N. T. Baerlecken, None; I. Berg, None; R. Ramonda, None; D. van der Heijde, None; F. van Gaalen, None; T. Witte, None; D. Baeten, UCB, 3.

To cite this abstract in AMA style:

de Winter J, van de Sande M, Baerlecken NT, Berg I, Ramonda R, van der Heijde D, van Gaalen F, Witte T, Baeten D. Diagnostic Value of Anti-CD74 Antibodies in Early Axial Spondyloarthritis: Data from the Spondyloarthritis Caught Early (SPACE) Cohort [abstract]. Arthritis Rheumatol. 2017; 69 (suppl 10). https://acrabstracts.org/abstract/diagnostic-value-of-anti-cd74-antibodies-in-early-axial-spondyloarthritis-data-from-the-spondyloarthritis-caught-early-space-cohort/. Accessed .

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