AB1311 EVALUATION OF A POTENTIAL INDUCTION OF AUTOANTIBODIES IN A COHORT OF PATIENTS AFFECTED BY RHEUMATOID ARTHRITIS, SYSTEMIC SCLEROSIS OR WITH TRIPLE POSITIVITY FOR ANTIPHOSPHOLIPID ANTIBODIES FOLLOWING ANTI-SARS-CoV2 VACCINATION

Background Vaccines anti-SARS-CoV2 showed a good efficacy in prevention of severe COVID-19 [1]. Their potential in induction of autoantibodies (abs) has not been well established [1]. One recent study demonstrated an increase of abs’ titer after anti-SARS-CoV2 vaccination only in patients (pts) with already pre-existing positivity [2]. Objectives To evaluate the potential induction of abs after SARS-CoV2 vaccination in a cohort of pts affected by Rheumatoid Arthritis (RA), Systemic Sclerosis (SSc) or with triple positivity for antiphospholipid antibodies (aPL). Methods Consecutive pts affected by RA, SSc or with triple positivity for aPL were enrolled from February 2021 to November 2021. Serum samples were collected before the first (T0) and at least one month after the second administration (T1) of the anti SARS-CoV-2 vaccine. A wide panel of abs were evaluated through routinely methods. Qualitative variables were compared using Chi-square test or Fisher’s exact test; quantitative variables were compared using Wilcoxon signed-rank test. Results 52 pts were considered [F/M= 48/4; median age=58(51-61.3) years; 15 RA, 19 SSc and 18 with triple positivity for aPL]. Regarding vaccination, 27 pts were administered BNT162b2, 24 mRNA-1273 and 1 Gam-COVID-Vac. No difference regarding frequency of abs’ positivity was found between T0 and T1, except for aB2GPI IgG, that showed a reduction in positivity frequency ( Table 1 ) No difference was found in the titer of the following abs: anti-dsDNA (p:0.318), anti-MPO (p:0.678) ed anti-PR3 (p:0.139). ACL IgG showed a significant reduction in chemiluminescence (CL) (T0 vs T1: 9.3 CU [6.1-41.6] vs 5.1 CU [2.5-35.7]; p:0.001), but not in ELISA (p:0.480). A significant reduction was found for aCL IgM both in CL (T0 vs T1: 5.7 CU [2.4-17.1] vs 3.4 CU [2.1-13.1]; p:0.006) and ELISA (T0 vs T1: 13.1 IU/ml [11.2-30.5] vs 11.2 IU/ml [11.2-19.5]; p:0.010). A significant reduction was found for aB2GPI IgG in CL (T0 vs T1: 25 CU [9.1-210.7] vs 6.4 CU [6.3-102.2]; p:0.001), but not in ELISA (p:0.953) Titre of aB2GPI IgM remained stable in CL (p:0.078) and ELISA (p:0.211). No variation was observed in ANA positivity. No significant difference was found in anti-ENA titre (p:0.141). None of the pts developed any new symptom or sign of autoimmune disease upon vaccination. Conclusion Anti-SARS-CoV2 vaccination didn’t induce any clinical sign of autoimmunity in this cohort of pts affected by RA, SSc or with triple positivity for aPL. Serology for abs remained stable in pts’ majority; only a fluctuation of aPL titre was found, generally in terms of reduction and without clinical significance. Reference [1]Ishay Y et al. Int Immunopharmacol. 2021; [2] Thurm C et al. medRxiv 2021. Table 1. Frequency of autoantibodies positivity before (T0) and after (T1) anti-SARS-CoV2 vaccination. Chi-square test or Fisher’s exact test were applied. In bold, statistically significant comparison. Autoantibodies Patients positive at T0 Patients positive at T1 p-value Anti-dsDNA* 8/51 (15.7%) 10/52 (19.2%) 0.636 aCL IgG * 18/51 (35.3%) 16/52 (30.8%) 0.625 aCL IgG° 10/50 (20%) 9/52 (17.3%) 0.727 aCL IgM* 10/51 (19.6%) 9/52 (17.3%) 0.763 aCL IgM° 27/50 (54%) 20/52 (38.5%) 0.116 aβ2GPI IgG* 28/51 (54.9%) 18/52 (34.6%) 0.038 aβ2GPI IgG° 10/50(20%) 12/52(23.1%) 0.706 aβ2GPI IgM* 9/51 (17.6%) 8/52 (15.4%) 0.757 aβ2GPI IgM° 9/50(18%) 10/52(19.2%) 0.873 aMPO° 8/50 (16%) 8/52 (15.4%) 0.932 aPR3° 7/50 (14%) 7/52 (13.5%) 0.844 dsDNA=double-stranded DNA; aCL: anti-cardiolipin; aβ2GPI: anti-beta2-glycoprotein I; aMPO: anti-myeloperoxidase; aPR3: anti-proteinase3 *= chemiluminescence method; °= ELISA method Acknowledgements: NIL. Disclosure of Interests None Declared.