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42. Kongress der Deutschen Gesellschaft für Rheumatologie, 28. Jahrestagung der Deutschen Gesellschaft für Orthopädische Rheumatologie, 24. Wissenschaftliche Jahrestagung der Gesellschaft für Kinder- und Jugendrheumatologie

17.-20. September 2014, Düsseldorf

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Functional role of autoantibodies against CD74 in axial Spondyloarthritis

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  • Wintering Oliver - Medizinische Hochschule Hannover, Klinik für Immunologie und Rheumatologie, Hannover
  • Kira Klose - Medizinische Hochschule Hannover, Klinik für Immunologie und Rheumatologie, Hannover
  • Katja Kniesch - Medizinische Hochschule Hannover, Hannover
  • Niklas Baerlecken - Medizinische Hochschule Hannover, Klinik für Immunologie und Rheumatologie, Hannover
  • Reinhold E. Schmidt - Medizinische Hochschule Hannover, Klinik für Immunologie und Rheumatologie, Hannover
  • Torsten Witte - Medizinische Hochschule Hannover, Klinik für Immunologie und Rheumatologie, Hannover

Deutsche Gesellschaft für Rheumatologie. Deutsche Gesellschaft für Orthopädische Rheumatologie. Gesellschaft für Kinder- und Jugendrheumatologie. 42. Kongress der Deutschen Gesellschaft für Rheumatologie (DGRh); 28. Jahrestagung der Deutschen Gesellschaft für Orthopädische Rheumatologie (DGORh); 24. wissenschaftliche Jahrestagung der Gesellschaft für Kinder- und Jugendrheumatologie (GKJR). Düsseldorf, 17.-20.09.2014. Düsseldorf: German Medical Science GMS Publishing House; 2014. DocSP.11

doi: 10.3205/14dgrh244, urn:nbn:de:0183-14dgrh2446

Published: September 12, 2014

© 2014 Oliver et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Background: Early treatment in SpA (Spondyloarthritis) may halt or delay the disease progression. However, making the diagnosis has been challenging for physicians resulting in a diagnosis delay of several years. Recently, autoantibodies against CD74 have been proposed as a new diagnostic marker in SpA. The aim of this study was to characterize CD74 as a T cell antigen, to isolate these autoantibodies from the serum of patients and to investigate their effect on PBMCs and monocytes.

Methods: PBMCs of 29 SpA patients, 20 rheumatoid arthritis (RA) patients and 17 healthy controls were isolated, stained for CD3, CD14, CD19, HLA-DR and CD74 and then analyzed by flow cytometry. The mean fluorescent intensity (MFI) of CD74 on T-cells, B-cells and monocytes was compared between the three groups using ANOVA. Subgroup analysis of the SpA group was performed, also using ANOVA. IgG, IgA and IgM antibodies against the recombinant extracellular domain of CD74 were measured by ELISA. IgG antibodies directed against CD74 were isolated from the blood of SpA patients using antigen specific affinity purification and their specificity against CD74 was confirmed by ELISA.

PBMC (1 Mio per stimulation) of 37 SpA patients, 20 RA patients and 13 healthy controls were incubated overnight with 1 µg of recombinant CD74 or with a control protein in the presence of brefeldin. Then, the intracellular production of TNF-α and of IFN-γ was measured in CD4+ T cells using flow cytometry

Results: The expression of CD74 was significantly lower on monocytes of SpA patients compared to blood donors (P=0.047). Subgroup analysis of the SpA group revealed that the reduced expression of CD74 on monocytes was significantly lower only in the patients not receiving a TNF inhibitor (P=0.019). In addition, patients without IgM antibodies against CD74 had a significantly lower expression of CD74 on monocytes (P=0.036).

A significantly higher subset of CD4+ T cells of SpA patients produced IFN-γ (P=0.0003) or TNF-α (P=0.0013) compared to RA patients and controls.

Conclusion: Functional studies with the isolated CD74 antibodies will help to identify the role of these markers in the pathogenesis of SpA.