Figure 3.
IL-33 significantly augments the ability of SARS-CoV-2 spike protein to stimulate the secretion of chymase, tryptase, and IL-1β from human mast cells. LADR mast cells (2.5 × 105 cells) were stimulated with recombinant full-length SARS-CoV-2 S protein (10 ng/mL) and IL-33 (30 ng/mL) for 1 h (A,B) and 24 h (C). Secretion of chymase (A), tryptase (B), and IL-1β (C) was determined by specific ELISAs. SP (2 μM), IL-33 (30 ng/mL), and their combination were used as “positive” controls. All conditions were performed in triplicate for each dataset and repeated 3 times (n = 3). The horizontal brackets indicate the corresponding levels of significance when present (p < 0.05 (*), p < 0.01 (**), p < 0.001 (***), and p < 0.0001 (****)).