FRI0224 Rituximab selectively reduces igg4 levels in rheumatoid arthritis patients

Background Rituximab has been applied as a therapeutic strategy in a variety of diseases, including Rheumatoid Arthritis (RA) and IgG4-Related Disease (IgG4-RD)1. On IgG4-RD, it has been shown that apart from B-cell depletion, rituximab induces remission by reducing IgG4 levels2. Objectives On this regard, we investigated weather B-cell depletion in RA is also associated with a selective reduction of any IgG subclass, especially IgG4. Methods 31 RA patients, 25/6 female/male, median age 59 years (34–73), duration of disease 9,5 years (1–30) on standard of care DMARD treatment and rituximab administration every 6 months for 2 years were investigated for alterations on disease activity along with Igs9 and IgG subclasses levels. All parameters were assessed at enrollment (T0), and after 6, 12 and 24 months. On this 2-year period all patients had been periodically receiving rituximab every 6 months. Results After 2 years of rituximab administration, patients achieved a good response to treatment (EULAR criteria). Igs9 levels were not statistically altered, though all of them declined (data for IgM and IgA not shown). Furthermore, from IgG subclasses, only IgG4 levels statistically declined. Conclusions This is the first time that IgG4 variations are investigated in a non-IgG4RD after rituximab administration. Our results imply that IgG4 may be actively implicated in RA pathophysiology, since disease remission is accompanied by only IgG4 level reduction among all classes and subclasses of Igs9. Furthermore, in RA patients, rituximab may exert its therapeutic results not only via B-cell depletion, but also via IgG4 levels reduction. References Carruthers MN, Topazian MD, Khosroshahi A, et al. Rituximab for IgG4-related disease: a prospective, open-label trial. Ann Rheum Dis. 2015 Jun;74(6):1171–7. Khosroshahi A, Bloch DB, Deshpande V, Stone JH. Rituximab Therapy Leads to Rapid Decline of Serum IgG4 Levels and Prompt Clinical Improvement in IgG4-Related Systemic Disease. Arthritis Rheum. 2010 Jun; 62(6): 1755–62. Disclosure of Interest None declared