POS0457 CHANGES OF RF ISOTYPE PROFILE IN PATIENTS WITH RHEUsMATOID ARTHRITIS: DATA FROM 10 YEARS FOLLOW-UP STUDY
Authors: M. R. Nur Aida Sabrina, C. L. Too, A. Haziqah Itqan, A. A. Siti-Aisyah, A. F. Nurul-Aain, L. K. Tan, I. S. Lau, M. Mohd Zain, H. Baharuddin, D. L. M. Ang, A. R. Amnahliza, P. S. Ong, N. Mat Husin, S. C. Gun, N. Mohd Noor, M. Z. Taib, L. Padyukov, L. Alfredsson, L. Klareskog, J. Rönnelid, N. S. Shahril
Journal: Annals of the Rheumatic Diseases (2021)

Background: Presence of autoantibodies such as anti-cyclic citrullinated peptide (anti-CCP2) and rheumatoid factor (RF) is of considerable diagnostic and prognostic value in patients with rheumatoid arthritis (RA). Limited data are available for autoantibody profile changes over time in patients with RA. Objectives: Thus, we compared the presence of anti-CCP2 and different RF isotypes in individual RA patients at baseline and during 10 years follow-up. Methods: A total of 320 RA patients from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) case-control study was included in this study. The presence of anti-CCP2, IgM RF, IgG RF, and IgA RF at baseline and at later time point (±10 years) were determined using enzyme-linked immunosorbent assays, with identical techniques in paired samples. Seropositive RA is defined by the presence of at least one autoantibody, whilst seronegative RA is defined by the absence of all investigated autoantibodies. Results: The proportion of seropositive RA were higher for the follow-up samples (n=263, 82.2%) as compared to the baseline samples (n=251, 78.4%). Among the baseline samples, 105 (41.8%) were positive for anti-CCP2 and all RF isotypes. Of these individuals, 85 (81.0%) remained positive for all antibodies at the follow-up, while 20 (19.0%) lost one or more RF isotypes (4 IgM RF, 19 IgG RF and 13 IgA RF). Interestingly, 14 (5.6%) RA patients who were seropositive at baseline became totally seronegative after follow-up. Among the 69 patients seronegative at baseline, 26 (37.7%) acquired one or more autoantibodies at follow-up (14 IgM RF, 2 IgG RF, 9 IgA RF and 8 anti-CCP2) (Figure 1). Conclusion: Anti-CCP2 present at baseline usually remained at follow-up. Among Malaysian RA patients, changes in status were mainly found for RF of all isotypes. References: [1]Barra, Lillian et al. “Lack of seroconversion of rheumatoid factor and anti-cyclic citrullinated peptide in patients with early inflammatory arthritis: a systematic literature review.” Rheumatology (Oxford, England) vol. 50,2 (2011): 311-6. [2]van Delft, Myrthe A M, and Tom W J Huizinga. “An overview of autoantibodies in rheumatoid arthritis.” Journal of autoimmunity vol. 110 (2020): 102392. Figure 1. Comparison of serum autoantibody profile in rheumatoid arthritis patients during baseline enrolment and 10 years follow-up. Acknowledgements: The authors would like to thank the Director General of Health, Ministry of Health Malaysia for supporting this study. The authors are also indebted to participants for their kind participation. This study was financially supported by the Ministry of Health, Malaysia (JPP-IMR 08-012; 18-051). Disclosure of Interests: None declared