Study population: Non-smoking healthy male volunteers, age 18-35 yrs Intervention: Subjects will receive C1INH in a dose of 100 U/kg (n=10) or placebo (n=10) 30 min after LPS administration. Pre-hydration will be performed by infusion of 1.5 L 2.5% glucose/0.45% saline solution in 1 hour before LPS administration. LPS derived from E coli O:113 will be injected (2 ng/kg iv., infusion rate 1 minute).