A monocyte is a leukocyte, part of the human body's immune system that protects against blood-borne pathogens and moves quickly (aprox. 8-12 hours) to sites of infection in the tissues. Monocytes are usually identified in stained smears by their large bilobed nucleus.

Monocytes are produced by the bone marrow from haematopoietic stem cell precursors called monoblasts. Monocytes circulate in the bloodstream for about one to three days and then typically move into tissues throughout the body. They consist of between 3 to 8 percent of the leukocytes in the blood. In the tissues monocytes mature into different types of macrophages at different anatomical locations.

125I-WVH-1

• shown to label the plasma membrane, as judged by known markers, and represents a highly specific trace label, applicable to the use of plasma membrane as an immunogen for monoclonal antibody production. PMID: 3971989

63D3

• 63D3 antigen expression is similar on peripheral blood monocytes and alveolar macrophages and may be a stable marker in the differentiation of monocytes to macrophages. PMID: 6349890

Adipophilin

• a sensitive marker for lipid loading in human blood monocytes. PMID: 11420178

Angiotensin Converting Enzyme

• is consistently induced in monocytes in culture. PMID: 2833377

CB12

• a differentiation marker specific for human monocytes and their bone marrow precursors. PMID: 3091273

CD11a (LFA-1 alpha)

• leukocyte-function-associated antigen, expressed on monocytes. PMID: 7557500

CD11b

• monocyte activation marker. PMID: 12868785

CD14

• the monocyte differentiation marker. PMID: 1717365
• surface molecule of human monocytes. PMID: 1706877
• monocyte activation marker. PMID: 15896827

CD15

• monocyte activation marker. PMID: 12868785

CD54

• a key factor in monocyte adhesion. PMID: 16920859

CD62L (L-selectin)

• monocyte activation marker. PMID: 12868785

CD163

• a monocyte/macrophage-specific marker. PMID: 15615263, PMID: 12570164

Cytidine Deaminase (CDD, EC 3.5.4.5)

• a marker of monocyte/macrophage differentiation. PMID: 8422236

DH59B

• a pan-granulocyte/monocyte surface molecule that reacted with a 96 kDa pan-granulocyte/monocyte specific surface protein and identified macrophages and Kupffer cells in equine tissue sections. PMID: 7750989

Fc-receptors

• human monocytes have two distinct Fc receptor sites, which must specifically and directly interact with T cell-bound anti-T3 antibodies for mitogenesis. PMID: 3923099
• Two distinct classes of IgG Fc receptors on a human monocyte line (U937) defined by differences in binding of murine IgG subclasses at low ionic strength. PMID: 2931481
• Two types of IgG FcR, FcRI and FcRII, are constitutively expressed by human monocytes. PMID: 2966198

Flt-1

• also known as vascular endothelial growth factor receptor 1 (VEGFR-1), is a novel cell surface marker for the lineage of monocyte-macrophages in humans. PMID: 11157498

HLA-DR

• Monitoring of monocyte HLA-DR expression may be a useful marker for identifying the patients who are at high risk of sepsis in acute pancreatitis. PMID: 12370535

hMGL

• the dermal hMGL(+) cells are a subset of differentiated cells derived from monocytes and that hMGL is a unique marker for cells at an intermediate stage of macrophage differentiation. PMID: 12039906

Ki-M1p

• a monocyte marker. PMID: 9236835

Leucocyte tartrate-resistant acid phosphatase (FATRE)

• a marker for the transition of monocyte to macrophage. PMID: 10347964

Leu-7

• The majority of Leu-7-positive cells coexpressed a monocyte phenotype and showed an ultrastructural pattern specific for functional natural killer (NK) cells. PMID: 3928537

Lysozyme

• a potential marker of monocyte/macrophage activity in rheumatoid arthritis. PMID: 10587554

Mannosyl Receptors

• may constitute an early marker for differentiation of monocytes into macrophages. PMID: 3918878

Peanut Agglutinin (PNA)

• a marker for normal and leukaemic cells of the monocyte lineage. PMID: 6809376

Thromboplastin

• a useful marker for monocyte differentiation. PMID: 6821657

Thymidine Phosphorylase (TP)

• a marker of protumor monocytes in breast cancer. PMID: 10353748

TNF (Tumor necrosis factor)

• a marker for monocyte function in chronic myeloid leukemia. PMID: 8630684

Urokinase (UK)

• a serine protease produced by activated human monocytes. PMID: 9715259

VEP8 and VEP9

• raised against the promyelomonocytic leukemia cell line HL60 have previously been shown to distinguish human granulocytes and monocytes from other cells of the peripheral blood. PMID: 6189722

Other Monocyte Markers

• colloidal gold uptake is a marker of monocyte differentiation and maturation and can provide additional information for ANLL cytology. PMID: 1498317
• Monocyte chemotaxis: a method for routine in vitro investigation using lactic dehydrogenase as a marker enzyme. PMID: 3577766
• alpha-naphthyl butyrate is a specific monocyte marker. PMID: 6658305
• A monoclonal antibody recognising a surface marker on rainbow trout (Oncorhynchus mykiss) monocytes. PMID: 11308075
• The cytochemical detection of monocytes, lymphocytes, neutrophilic and eosinophilic granulocytes by using marker enzymes. PMID: 2168830
• The thiol-proteindisulfide-oxidoreductase--a new marker enzyme of monocytes from peripheral blood. PMID: 2951987
• Monocyte markers – review article. PMID: 2080277