FIGURE 4.

PD‐L1 is required for WJMSC sEVs to modulate TCR signalling pathway. (a) Representative flow charts showing the activation of CD4⁺ T cells incubated with 20 µg/ml PD‐L1 WT or KO WJMSC sEVs for 20 min (left) and quantitative analysis (right). (b) Expression of phospho‐ZAP70 protein (pZAP70) in activated CD4⁺ T cells mentioned above, measured by flow cytometry (left) and quantitation (right). (c) Schematic of PD1‐NFAT reporting system in Jurkat T cells stimulated with 1:1 ratio CD3/CD28 Dynabeads and co‐incubated with 20 µg/ml PD‐L1 WT and KO WJMSC sEVs plus 3 µg/ml PD‐L1‐iAb/isotype for 12 h or 36 h. LUCNFAT, luciferase gene under the control of NFAT response elements; PD‐L1‐iAb, neutralization antibody for human PD‐L1. (d) Quantitative analysis from c (n = 3). Data are mean ± s.e.m and analysed by one‐way ANOVA (a,b,d)