Modulation of molecular imprints in the antigen‐experienced B cell repertoire by rituximab

Abstract

Objective. Transient B cell depletion by rituximab has recently gained more importance in the treatment of rheumatic disorders. Nevertheless, little is known about the reemerging B cells. We analyzed dynamic changes in the repopulating B cells, particularly the postswitch B cells, and studied the mutational patterns of Ig genes in antigen-experienced B cells.Methods. Five patients with active rheumatoid arthritis (RA) were treated with rituximab. In 3 patients, B cell receptor (BCR) gene analysis was performed before treatment and during B cell recovery using genomic DNA. In 2 patients, B cell subsets were studied during the early recovery phase using single-cell technology. For comparison, immunophenotyping of B cell subsets was performed.Results. Early B cell recovery was marked by a relatively expanded population of highly mutated B cells, which were correlated with B cells with a plasmablast phenotype on comparative immunophenotyping. Analysis of the mutational pattern in these cells revealed increased RGYW/WRCY (where R ‫؍‬ A/G, Y ‫؍‬ C/T, and W ‫؍‬ A/T) hotspot targeting (44% before rituximab versus 59% after) and elevated ratios of replacement to silent mutations within the complementarity-determining regions in Ig genes (1.87 before rituximab versus 2.67 after; P < 0.0025).Conclusion. Our findings show that rituximab leads to qualitative changes in the imprints of highly mutated, antigen-experienced BCRs, representing the result of selection, whereas molecular processes such as Ig V rearrangements are not affected by this treatment.

Delayed acquisition of somatic hypermutations in repopulated IGD+CD27+ memory B cell receptors after rituximab treatment

“…Previous work in our laboratory provided evidence of an impact on molecular imprints shaping the Ig repertoire with similar mutational targeting of all V H gene families (V H 1-V H 6) (29). Changes in the pattern of somatic hypermutation after temporal B cell depletion by rituximab have also been observed (32).…”

Optimising treatment in rheumatoid arthritis: a review of potential biological markers of response

“…Open-label studies in RA have shown that the presence of B cell subsets during depletion or repletion may be a predictor of reduced response or early relapse 83–86. Indeed, a lack of complete depletion of plasma B cells after an initial infusion with rituximab was associated with a poorer response than for patients in whom depletion was complete 83 87.…”

B cells in the pathogenesis and treatment of rheumatoid arthritis

“…We have also found that B cell depletion may alter lymphoid architecture by eliminating LTα bearing and TNF secreting B cells, resulting in a prolonged delay in memory B cell reconstitution that correlates with clinical response in SLE [54]. Such mechanisms may explain the delayed acquisition of mutations in the memory B cell compartment after rituximab [55,56]. …”