Background Recently, we described that non-responders to anti-TNF therapy in rheumatoid arthritis (RA) had significantly lower levels of antibodies targeting phsphorylcholine (anti-PC)
Since we had observed anti-inflammatory properties of human polyclonal anti-PC vitro, we generated a panel of fully human monoclonal antibodies to PC (anti-PC mAbs).
Objectives In this study we aimed at investigating effect of anti-PC mAbs on basal and TNF-induced IL-6 secretion and ICAM-1 expression in synovial-like fibroblasts from a healthy and a RA donor.
Methods Fully human monoclonal antibodies targeting PC of IgG1 isotype were generated from healthy human donors via single-cell sorting of PC-reactive B-cells and consequent cloning/production in human embryonic kidney (HEK) cell system. Synovial-like fibroblasts from a healthy and a RA donor at passage 3 were cultured under serum-free conditions for 12 hrs, pre-incubated with 2 clones of anti-PC mAbs (A01 and E01) at 5 μg/ml for 1 hr. TNF was added at 10 ng/ml. IL-6 levels in cell culture supernatants were measured after 12 hrs by high-sensitivity commercial ELISA. ICAM-1 and VCAM-1 was analysed by flow cytomery.
Results A significant decrease in both basal and TNF-induced IL-6 level in cell supernatants of RA synoviocyte-like fibroblasts was observed with anti-PC mAbs Simultaneously, a significant decrease in surface expression of both ICAM-1 and VCAM-1 was observed. Anti PC mAbs excerted similar effect on TNF-induced Il-6 adn ICAM- 1 expression in healthy synoviocytes.
Conclusions Fully human anti-PC mAbs could be produced by single-cell sorting of PC-reactive B-cells and consequent cloning/production in a human cell system. Anti-PC mAbs inhibit both basal and TNF-induced IL-6 levels in cultured synoviocyte-like fibroblasts from rheumatoid arthrtis. Further, there was a variation in the effects between clones. Our data suggest that anti PC mAbs could be of therapeutic interest.
Disclosure of Interest D. Thiagarajan: None declared, V. Malmstrom: None declared, J. Frostegård Shareholder of: JF is named as co-inventor in patents/patent applications in relation to anti-PC, R. Fiskesund Shareholder of: RF is named as a co inventor on a pending patent application in rleation to anti OC mAbs, J. Steen: None declared, A. Frostegård Shareholder of: AF is named as a co-inventor in pending patent application in relation to anti PC