Daratumumab treatment reduced the abundance of B cells and affected subset distributions of T cells. PBMCs from 2 patients with wAIHA at different time points: baseline (Pre), during treatment (Mid), immediately after treatment cessation (EOT), 6 weeks after the last cycle (6 weeks), and 3 months after end of treatment (Post) were analyzed by flow cytometry, either right after thawing or after a 2- to 5-day culture-cell stimulation by αCD3/αCD28 antibodies. (A) Frequency and subset distribution of B cells over the course of daratumumab treatment. (B) Analysis of CD3⁺ and T_reg frequency, CD4⁺: CD8⁺ ratio, CD4⁺subset distribution and CD38 expression. (C) Hemoglobin (g/dL) levels of patients over course of treatment. CM, central memory; EM, effector memory; EMRA, effector memory RA⁺.