The role of the kininogens as cysteine proteinase inhibitors in local and systemic inflammation.

The contribution of the kininogens and cystatin C to the functional inhibitory capacity for cysteine proteinases of blood plasma and inflammatory secretions was estimated from ex vivo experiments. 98.5% of the inhibitory capacity of blood plasma for cathepsin L (4-5 microM) is provided by the kininogens ensuring a complete control of this enzyme even at a lowered kininogen concentration. Control of cathepsin B activity by the kininogens is incomplete and depends critically on the active concentration of cystatin C (70 nM in normal plasma), which is reduced in blood plasma of polytraumatized and septic patients and very low in epithelial lining fluid of the shock lung.