| Monocytes are formed in the bone marrow and mature from monoblasts to promonocytes to monocytes. Monocytes enter the peripheral blood for ~24-36 hr and exit into tissues and become fixed tissue macrophages (eg, Kupffer’s cells) or migrating macrophages at sites of inflammation. Monocytes and
macrophages can perform pinocytosis and phagocytosis and form multinucleated giant cells in the tissue, particularly in response to foreign bodies. Monocytes and macrophages are a major source of colony-stimulating factors and cytokines that regulate inflammatory responses, and they function as antigen-processing cells.
Monocytosis may be associated with chronic inflammation (particularly mycotic and other granulomatous infections), endocarditis, bacteremia, or corticosteroid or stress responses (especially in dogs).
Monocytopenia is occasionally seen but usually has no diagnostic significance. |
