Mean percentage changes in B cells and B-cell subsets. Mean percentage changes in total mature (CD20 + CD3-) (A), immature (CD19 + CD27 - IgD-) (B), mature naïve (CD19 + CD27 - IgD+) (C) and switched memory (CD19 + CD27 + IgD-) (D) B cells are shown. The week 0 comparison is of the B cells to pretabalumab baseline counts before dosing with tabalumab. For patients who received tabalumab in the first or second randomized controlled trial, the pretabalumab baseline count represents B-cell count at a time point prior to week 0 of this open-label extension study. All patients were required to have B-cell follow-up through week 72; only patients who did not meet the definition of recovery were required to have follow-up beyond week 72. Data after week 100 are not shown, as there were fewer than five patients per arm. Ig, immunoglobulin; N, Number of patients per treatment arm; n, number of patients assessed at a given time point.