Figure 2. Plasmacytoid DCs can sense SARS‐CoV‐2 and induce an inflammatory response.

• A, B
  pDCs were either mock treated or exposed to the SARS‐CoV‐2 FR2020 early Wuhan‐like strain or the SARS‐CoV‐2 alpha variant B.1.1.7 (0.1 MOI). Supernatants were collected at indicated time points and the production of type I IFNα (A) and CXCL10 (B) was quantified.
• C–J
  The FR2020 strain was used in subsequent experiments where pDC were either mock treated (mock, grey), exposed to SARS‐CoV‐2 at 1 MOI (SARS‐2, purple), TLR7 (2.5 μg/ml R837, blue), or TLR3 agonist (800 ng/ml poly(I:C), pink). Supernatants were collected after 24 h and analyzed for type I IFNα (C), IFNβ (D), type II IFNγ (E), type III IFNλ1 (F), IL‐6 (G), IL‐8 (H), CXCL10 (I), and TNFα (J) expression by ELISA.
• K–M
  To evaluate the cytokine response to viral titers and exposure duration, pDCs were exposed to increasing viral inoculums (MOI of 0.01, 0.1, and 1) and IFNα2a mRNA expression was quantified at 24 h (K) and IFNα protein secretion at 24, 48, 72, and 96 h (L). Graph depicting simple linear regression of IFNα protein with time of exposure (M).

Data information: Bars (A–L) and line (M) represent mean values with standard error of the mean (M) and symbols represent individual pDC donors (n = 3–4). Equal symbols represent equal donors (A–B and C–L). Statistical significance was determined using the ratio‐ paired student t test and compared the treated condition with the time point‐matched mock condition (A–L) and simple linear regression (M). *P < 0.05, **P < 0.01, ***P < 0.001.