Figure 6.

Spike protein captures endotoxin to induce cytokine expression. Rested PBMC were cultured for 3 h in wells, which were coated with or without 100 µL of streptavidin (STAV, 2.0 µg/mL) and S1-biotion from Vendor #1 together with 0.15, 0.3 or 0.6 EU/mL LPS. The levels of IL-6, IL-8 and TNFα in the supernatants of cultured PBMC were measured using the CBA human inflammatory cytokine kit and flow cytometric analysis. The concentrations of IL-8 in the supernatants were also measured using an ELISA kit. Data shown in (A) are representative of the flow cytometric results from four healthy donors, and data shown in (B) are mean of cytokine induction indices (fold) ± SE derived from four healthy donors, which were calculated using cytokine concentrations measured by the CBA assay (IL-6 and TNFα) or the ELISA (IL-8) and the formula: cytokine concentration of treated PBMC/cytokine concentration of untreated PBMC.. Statistical analyses were performed using two-tailed, Student’s t-test. * and ** depict p < 0.05 and 0.01, respectively.