Overall, pDC production of IFN-α and TNF-α upon TLR-9 and TLR-7 stimulation was lower in SLE subjects treated with HCQ (TLR-9: 2% ± 2.2 CD123+IFN-α+; 1.4% ± 2.9 CD123+TNF-α+) (TLR-7: 3.3% ± 3.8 CD123+IFN-α+; 3.7% ± 3.7 CD123+TNF-α+) compared to SLE subjects who were not receiving HCQ (TLR-9: 8.6% ± 4.3 CD123+IFN-α+, P < 0.0001; 11.8% ± 9.1 CD123+TNF-α+, P < 0.0001) (TLR-7: 5.3% ± 3.9 CD123+IFN-α+, P = 0.058; 7.4% ± 7.4 CD123+TNF-α+, P = 0.054) (Figure 4). Here, TLR7 is linked to systemic lupus erythematosus.