A member of the S-100 protein family that is present at high levels in the blood and interstitial fluid in several infectious, inflammatory, and malignant disorders, including rheumatoid arthritis, inflammatory bowel disease, and cystic fibrosis. It is a complex of a light chain (calgranulin a) and a heavy chain (calgranulin b). L1 binds calcium through an EF-hand motif, and has been shown to possess antimicrobial activity.