Histiocyte

Source: Wikipedia, the free encyclopedia.
Histiocyte
Details
SystemImmune system
Identifiers
Latinmacrophagocytus immobilis
MeSHD006644
THH2.00.03.0.01009
FMA84642 83585, 84642
Anatomical terms of microanatomy

A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyte is a tissue macrophage[1] or a dendritic cell[2] (histio, diminutive of histo, meaning tissue, and cyte, meaning cell). Part of their job is to clear out neutrophils once they've reached the end of their lifespan.

Development

Histiocytes are derived from the

mononuclear phagocytic system
(MPS).

However, the term histiocyte has been used for multiple purposes in the past, and some cells called "histocytes" do not appear to derive from monocytic-macrophage lines.[3] The term Histiocyte can also simply refer to a cell from monocyte origin outside the blood system, such as in a tissue (as in rheumatoid arthritis as palisading histiocytes surrounding fibrinoid necrosis of rheumatoid nodules).

Some sources consider Langerhans cell derivatives to be histiocytes.[4] The Langerhans cell histiocytosis embeds this interpretation into its name.

Structure

Histiocytes have common

CD45, CD14, CD33, and CD4 (also expressed by T helper cells
).

Macrophages and dendritic cells

These histiocytes are part of the immune system by way of two distinct functions: phagocytosis and antigen presentation. Phagocytosis is the main process of macrophages and antigen presentation the main property of dendritic cells (so called because of their star-like cytoplasmic processes).

TNF and IL-4. The various categories of histiocytes are distinguishable by their morphology, phenotype
, and size.

Langerhans cells

A subset of cells differentiates into

thymocytes (cells of the cortex of the thymus gland). They also express S-100, and their cytoplasm contains tennis-racket like ultra-structural inclusions called Birbeck granules
.

Clinical significance

See also

References