Calprotectin is a protein complex from the S-100 family, which is formed of three polypeptide chains, two heavy and one light 3. It was first purified in 1980 and called L1 protein by the group that discovered it, although like many proteins has had multiple names 3.
It is found in especially heavy concentrations in neutrophils and monocytes, and more generally within skin cells, with an organ distribution including the lungs, gastrointestinal tract, oral and cervical mucosae and associated body fluids/secretions.
There are many commercially-available testing kits for calprotectin, many using ELISA (enzyme-linked immunosorbent assay) techniques.
Fecal calprotectin is primarily employed in two scenarios:
- distinguish inflammatory bowel disease from irritable bowel syndrome
- assay disease activity in inflammatory bowel disease