Presence of ABC-like cells in human peripheral blood. (A) Percentage of ABC-like cells among CD19⁺ cells in the peripheral blood of patients with RA, SSc, or SLE, or in HDs. Statistical analysis performed using the Mann-Whitney test. (B) Percentage of ABC-like cells among CD19⁺ cells in peripheral blood of women > 60 years old, women < 60 years old, or men among patients with RA. Statistical analysis performed using the Mann-Whitney test. (C) Correlation of percentage of ABCs among CD19⁺ B cells in blood with the age of female patients with RA. (D) Phenotypic characterization of human ABCs (red) and other B cells (black). Gating strategy is shown at the top part of the figure.