Usefulness of monitoring of B cell depletion in rituximab-treated rheumatoid arthritis patients in order to predict clinical relapse: a prospective observational study

International audienceOur objective was to evaluate the contribution of monitoring B cell subsetdepletion after rituximab in patients with rheumatoid arthritis (RA) in orderto guide reintroduction to forestall relapse. This prospective, monocentrestudy included all RA patients receiving two 1-g rituximab infusions at a15-day interval. The patients were followed clinically and biologically every 2months until rituximab reintroduction. The physician was blinded tolymphocyte-typing results to diagnose relapse and, hence, retreatment.Among the 39 patients included between March 2010 and December 2011and followed until April 2013, seven received two rituximab cycles, yielding atotal of 46 cycles for analysis. After the two rituximab cycles, the totalnumber of CD19+ B cells decreased significantly (0·155 versus 0·0002 G/l,P < 0·0001), with complete depletions in all patients of CD19+CD38++CD24++(transitional) (P < 0·0001) and CD19+CD27+ (memory) B lymphocytes. Asignificant majority of patients relapsed within the 4 months followingrepopulation of total B (P = 0·036), B transitional (P = 0·007) and B memory(P = 0·01) lymphocytes. CD19+ B lymphocyte repopulation preceded clinicalRA relapse and enabled its prediction 4 months in advance. Hence, monitoring of CD19+ B lymphocytes could serve as a tool to predict those relapse