pDCs are more sensitized to pSS plasma-induced apoptosis
Finally, we sought to explore the potential mechanism of reduced pDC frequency in the peripheral blood of pSS patients. Incubation of plasma from pSS patients could significantly reduce pDCs viability than that from HCs (Fig 5a). Considering that pSS is characterized by high autoantibodies in serum and pDC could promote antibody production as we demonstrated above, we inferred that plasma-derived IgG and IgA might be important inducers of pDC apoptosis. As we expected, both IgG and IgA dramatically increased the apoptotic rates of pDCs in a dose-dependent manner (Fig 5b-e). The viability of freshly isolated pDCs showed no significance between pSS and HCs (Fig S5a). Although pSS had higher serum IFN-α levels (Fig S5b), they had little effect on the pDC apoptosis (Fig S5c-e). These results indicate that hyper immunoglobulin in the serum of pSS patients contributes to the reduction of pDC in the peripheral blood (Fig 6).