Fig. 5

PKS21221 induced apoptosis and cell death in differentiated antibody-secreting cells (ASCs) and CD19⁺ B cells. PBMCs were cultured with or without IL-2/R848 for 5 days, followed by 12-h incubation with PKS21221 at different concentrations. a Representative flow cytometry plots of cells treated with IL-2 and R848 in the presence and absence of PKS21221. IL-2 and R848 differentiated B cells into CD27⁺CD38⁺ antibody-secreting cells (ASCs). PKS21221 reduced the percentage of ASCs. b Viability of total PBMCs using 7-aminoactinomycin D (7-AAD). 12-h treatment with PKS21221 did not affect overall viability of PBMCs. c A representative plot of apoptosis and viability assay using Annexin V and 7-AAD. Annexin V⁺7-AAD⁻ cells were referred as “Early apoptosis” population, and Annexin V⁺7-AAD⁺ cells were referred as “Dead” population. d Percentage of early apoptotic ASCs (left) and dead ASCs (right), after 12-h incubation with PKS21221. PKS21221 treatment induced apoptotic cell death in a dose-dependent manner. e Early apoptotic (left) and dead (right) populations in CD19⁻ non-B cells and CD19⁺non-ASCs. Experiments were repeated on PBMCs from 5 donors in 5 separate experiments, each data points in b and e, were the mean + SEM of three technical replicates. *p < 0.05, **p < 0.01, ***p < 0.001, by t-test compared with non-treated group