This gene encodes a secreted inhibitor which protects epithelial tissues from serine proteases. It is found in various secretions including seminal plasma, cervical mucus, and bronchial secretions, and has affinity for trypsin, leukocyte elastase, and cathepsin G. Its inhibitory effect contributes to the immune response by protecting epithelial surfaces from attack by endogenous proteolytic enzymes, the protein is also thought to have broad-spectrum anti-biotic activity. Synonyms: Polyclonal SLPI antibody, Anti-SLPI antibody, secretory leukocyte peptidase inhibitor antibody, ALK1 antibody, ALP antibody, BLPI antibody, HUSI antibody, HUSI-I antibody, MPI antibody, WAP4 antibody, WFDC4 antibody.