CD19 and autoimmune disease: Compared to current K-PD models of rituximab in autoimmune diseases (Pan et al., 2019; Riva et al., 2023), the t1/2 of CD19+ B-cell (99 days) was higher than that reported by the former (35 days), but lower than the latter (173 days), and ED50 was similar (1.31 versus 0.81 versus 0.692 mg), while Emax were higher (390 versus 35.2 versus 155 mg).