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).