Protease that degrades several proteins of the host immune system. Cleaves P-selectin glycoprotein ligand-1 (PSGL-1), leading to its functional inhibition; PSGL-1 is a leukocyte cell-surface receptor essential for leukocyte recruitment to the site of infection. Next to PSGL-1, targets host CD43 and CD44 that are also involved in leukocyte homing. Thus, prevents neutrophil extravasation and thereby protects P.aeruginosa from neutrophil attack. Is also able to inhibit the decay accelerating factor (CD55), but not the cell-surface receptors CD46 and CD31. Proteolytic activity is blocked in the presence of EDTA. Belongs to the peptidase M88 family.