Monocytes are produced in the bone marrow, circulate in the blood for a few days, and mature into macrophages or dendritic cells in different tissues, such as the liver and the spleen.
Human monocytes are divided in three major populations; classical (CD14+CD16−), non-classical (CD14dimCD16+), and intermediate (CD14+CD16+).
Monocytes are involved in human chronic diseases, such as obesity, atherosclerosis, chronic obstructive pulmonary disease, lung fibrosis, lung cancer, and Alzheimer's disease.
(Source: Kapellos, 2019)