The Monocyte: New Concepts of Function

Abstract

Blood monocytes are usually thought of as a minor subgroup of circulating phagocytic leukocytes that play a prominent part only in certain chronic infections such as tuberculosis. However, the role of this cell has been expanded considerably by studies in the past decade, which clarified the kinetics of the monocyte life cycle and its relation to tissue macrophages.¹ Tissue macrophages, regardless of their semantic label (Kupffer cells, fixed splenic histiocytes, pulmonary alveolar macrophages, epithelioid cells, etc.), originate primarily from the bone marrow where they have a generation time of about 24 hours. They circulate as monocytes for one to three . . .