Inflammatory and Physiological Roles of Chemokines.

Chemokines, members of the family of chemotactic peptides, have a well documented function in different inflammatory diseases where they induce leukocyte emigration into lesions. Several recent observations indicate that, in addition to pathological states, chemokines are also produced and secreted under physiological conditions by various exocrine glands in amounts sufficient for their full biological effect. The glands involved in chemokine production and secretion include eccrine sweat glands, lactating mammary glands, lacrimal and salivary glands. It is suggested that analogous to their role in inflammatory diseases, chemokines produced by the exocrine glands are responsible for the induction of homeostatic leukocyte migration into mucosal epithelia and skin and also, mammary glands and milk. In addition, the mechanism by which chemokines induce leukocyte homing under physiological circumstances is discussed.