IL1B and infection: To further examine whether the cytokines induced in early infection were mediated by quickly released IL-1β, THP-1 cells were pre-incubated with recombinant IL-1ra, which effectively suppresses the amount of IL-8 released in response to 10 ng/ml recombinant IL-1β, a dose 80–100 times higher than that induced by S. aureus infection (Fig. 4A).