Skip to main content
. 2021 Jul 14;22(14):7540. doi: 10.3390/ijms22147540

Figure 2.

Figure 2

Cytokine responses in human PBMC induced by various commercial coronavirus spike proteins. (A) Rested PBMC were cultured with or without 2.0 µg/mL of raxibacumab (human anti-anthrax PA IgG used as a negative control), MERS S1-Fc, SARS CoV-1 S1-Fc, SARS CoV-2 S1-Fc from Vendor #2 (V#2 S1-Fc) and Vendor #1 (lot 24529-2003, V#1 S1-Fc 2003), and RBD-Fc from Vendor #2 (V#2 RBD-Fc) and Vendor #1 (lot 24530-2003, V#1 RBD-Fc 2003) for 24 h. (B) Rested PBMC were cultured with or without plate-bound streptavidin (STAV) together with or without S1-biotin and RBD-biotin purchased from Vendor #2. The levels of IL-6 and TNFα were measured using the CBA human inflammatory cytokine kit and flow cytometric analysis. IL-8 levels were measured using an ELISA kit. The concentrations of the cytokines were calculated based on the standard curves, and the induction of cytokines were presented as cytokine induction (fold) calculated using cytokine concentrations and the formula: cytokine concentration of treated PBMC/cytokine concentration of untreated PBMC. Data shown are statistical results (mean ± SE) generated from 8 (A) or 3 (B) healthy donors. Statistical analyses were performed by Excel using a two-tailed, Student’s t-test. *, **, *** and **** depict p < 0.05, 0.01, 0.005 and 0.001, respectively.