Plasma chitotriosidase in health and pathology

Chitotriosidase (Chit), a member of the mammalian chitinase family, structurally homologous to chitinases from other species, is synthesized and secreted by specifically activated macrophages. After discovery of a striking increase of plasma Chit activity in serum from Gaucher's disease type I patients, an increasing number of inherited and acquired conditions sharing macrophage activation have been associated with increased Chit activity. In addition to lipid storage disorders, where Chit activity has longer been used as a marker of disease activity and therapeutic response, elevation of plasma Chit may occur in hematological disorders with storage of erythrocyte membrane breakdown products as thalassemia and different systemic infectious diseases sustained by fungi and other pathogens. Recently, increased Chit activity was demonstrated in CNS from patients with different neurological disorders. After a wide range of unwanted stimuli such as those occurring in stroke, multiple sclerosis, and Alzheimer's disease, resident cells like microglia and a few other cell types promptly activate a complex immune cascade which then might be monitored also by measuring Chit activity. The increased activity of Chit, wherever it is documented, represents one ancestral response of innate immunity which may have a wide range of clinical applications.