The antimicrobial peptide LL‑37, the only cathelicidin found in humans, is naturally made in salivary glands and its production goes up when the glands are inflamed, hinting it helps protect the mouth from microbes.

Salivary secretions play a critical role in maintaining oral health via innate host defense mechanisms and secretion of secretory IgA. One of the antimicrobial peptides, LL-37, is the only cathelicidin protein that has yet been identified in humans. Cathelicidins are a family of peptides thought to provide an innate defensive barrier against a variety of potential microbial pathogens. To examine the expression of cathelicidin in human salivary glands and to investigate up-regulation of cathelicidin in inflammatory conditions. Reverse transcriptase-polymerase chain reaction and immunohistochemical staining were performed on 20 salivary gland tissues, 10 from normal salivary glands and 10 from glands with chronic sialadenitis. Cathelicidin messenger RNA transcripts were detected in the tissues from the normal salivary glands and the glands with chronic sialadenitis. The level of cathelicidin messenger RNA in glands with chronic sialadenitis was significantly increased compared with that in normal salivary glands. Cathelicidin protein was expressed in the glandular epithelium of the normal salivary glands and the glands with chronic sialadenitis. The results indicate that cathelicidin might play an important role in innate host defense of human salivary glands.