Ig-receptor somatic hypermutation of gene rearrangements during IL-6R and TNF-α inhibition in DN B cells. (A) Ig-VH3 gene rearrangements during IL-6R inhibition. Reduction in mutational frequency of Ig-VH3 gene rearrangements of DN B cells from the peripheral blood of RA patients during TCZ therapy. The mutational frequency was significantly reduced at week 12, 24 and 1 year (***
P <0.0001 compared to BL). (B) Ig-receptor somatic hypermutation of VH3 gene rearrangements during TNF-α inhibition. During TNF-α inhibition by adalimumab, a comparable mutational frequency of VH gene rearrangements of DN B cells from the peripheral blood of RA patients were observed at all time points. (C) Ig-receptor somatic hypermutation of isotype-specific IgA+, IgG+ and IgM+ gene rearrangements during IL-6R inhibition in DN B cells. At the BL, the mutational frequency of IgA+ DN B cells is significantly higher compared to IgG+ and IgM+ DN B cells. During TCZ therapy, all isotypes IgA+, IgG+ and IgM+ DN B cells showed a significantly reduced mutational frequency (***
P <0.001). In a scatter plot, the line represents mean of all values and each dot depicts the mutational frequency of a single sequence. P values were determined by Wilcoxon test using GraphPad Prism 5. (BL, baseline; W12, week 12; W24, week 24; n, number of individuals; s, number of sequence analyzed). DN, double-negative; HD, healthy donor; Ig, immunoglobulin; IL-6R, interleukin-6 receptor; RA, rheumatoid arthritis; TCZ, tocilizumab; TNF-α, tumor necrosis factor alpha.