CXCL8 and cystic fibrosis: Therefore, to evaluate the effect of LL-37 on the IL-8 inducing ability of such LPS preparations, THP-1 monocytes were pre-treated with LL-37 (5 μg/ml) for 1 h prior to stimulation with LPS extracted from P. aeruginosa strains isolated from the lungs of two CF patients with severe lung disease (SE4 and SE22) for 24 h.