Given that Tfr and Tfh share the surface marker CXCR5 and that the restoration of the Tfr/Tfh imbalance is closely associated with the amelioration of SLE [31], we hypothesized that MSC-Exos may concurrently inhibit Tfh while promoting Tfr expansion and function. Here, CXCR5 is linked to systemic lupus erythematosus.