The monocyte and granulocyte azurophilic granule proteinases elastase, proteinase 3, and cathepsin G are implicated in acute and chronic diseases thought to result from an imbalance between the secreted proteinase(s) and circulating serpins such as a1-proteinase inhibitor and a1-antichymotrypsin. We show here that the intracellular serpin, proteinase inhibitor 6 (PI-6), is present in monocytes,...