Katy, 

 

Each of these have their pitfalls, limitations, and functional implications
and could form a useful panel to characterize monocyte/macrophage/histiocyte
populations and differentiation. 

 

 F4/80 antigen is an approximately 125 kDa transmembrane protein  expressed
by a majority of mature macrophages. However, other cell types such as
Langerhans cells and liver Kupffer cells have been reported to express this
antigen. Expression of F4/80 commences during early myeloid development with
approximately 30% of BM cells staining. F4/80 is upregulated on all BM cells
stimulated in vitro with M-CSF. It has been shown that some cytokines
downregulate the expression of F4/80 resulting in lack of F4/80 antigen on a
subpopulation of macrophages, especially in the lymphoid microenvironment in
vivo.

 

CD68 is a cytoplasmic antigen, a membrane glycoprotein closely associated
with lysosomes. Langerhans' cells and other dendritic cells are commonly
CD68 negative. CD68 is expressed throughout monocyte differentiation,
usually more intense in macrophages than monocytes. Granulocytic precursors
and mast cells may also exhibit CD68 positivity.

 

Factor-XIIIa-positive dendrocytes are resident dermal and stromal cells in
collagenous connective tissue that belong to the
monocyte-macrophage-dendrocyte  lineage. Factor XIIIa is a tissue
tranglutaminase that catalyses the cross linkage of fibrin and many other
matrix proteins, and it modulates fibroblast cytoskeleton and adhesion.
FXIIIa+ denritic histiocytes  are numerous in and are considered to play a
pivotal role in the skin response to injury, wound healing,  and
inflammation and form large populations in many so-called fibrohistiocytic
tumors. These cells appear to differentiate into CD68+ phagocytic
macrophages, especially in xanthogranuloma.  They can be rounded monocytoid,
epithelioid  to histiocytoid or quite dendritic and fibroblast-like. 

 

Jeff Silverman HT HTL QIHC (ASCP)

Southside Hospital

North Shore Long Island Jewish Health System

Bay Shore, New York USA

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