Development and Structure of Histiocytes
- Histiocytes are derived from bone marrow through multiplication from a stem cell.
- Derived cells migrate from bone marrow to the blood as monocytes.
- Monocytes circulate through the body and enter various organs.
- In organs, monocytes differentiate into histiocytes.
- Histiocytes have common histological and immunophenotypical characteristics.
- Their cytoplasm is eosinophilic and contains lysosomes.
- Histiocytes bear membrane receptors for opsonins like IgG and complement fragment C3b.
- They express leucocyte common antigens (LCAs) CD45, CD14, CD33, and CD4.
- CD4 is also expressed by T helper cells.
Macrophages and Dendritic Cells
- Macrophages and dendritic cells are part of the mononuclear phagocytic system (MPS).
- Macrophages specialize in phagocytosis.
- Dendritic cells specialize in antigen presentation.
- Both cells are derived from common bone marrow precursor cells.
- Differentiation into histiocytes is influenced by tissue location and growth factors.
Langerhans Cells
- Langerhans cells differentiate from a subset of histiocytes.
- Maturation occurs in squamous epithelium, lymph nodes, spleen, and bronchiolar epithelium.
- Langerhans cells are antigen-presenting cells.
- They express CD1a and S-100.
- Their cytoplasm contains Birbeck granules.
Clinical Significance of Histiocytoses
- Histiocytoses are neoplasias where the proliferative cell is the histiocyte.
- The most common histiocyte disorders are Langerhans cell histiocytosis and haemophagocytic lymphohistiocytosis.
- Langerhans cell histiocytosis involves skin, lymph nodes, spleen, and bronchiolar epithelium.
- Haemophagocytic lymphohistiocytosis affects immune cells and can be life-threatening.
- Accurate diagnosis and treatment are crucial for managing histiocytoses.
Miscellaneous
- Histiocytes are part of the mononuclear phagocytic system (MPS).
- Histiocytes express leucocyte common antigens (LCAs) CD45, CD14, CD33, and CD4.
- CD4 is also expressed by T helper cells.
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 or a dendritic cell (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.
Histiocyte | |
---|---|
Details | |
System | Immune system |
Identifiers | |
Latin | macrophagocytus immobilis |
MeSH | D006644 |
TH | H2.00.03.0.01009 |
FMA | 84642 83585, 84642 |
Anatomical terms of microanatomy |
histio- (“tissue”) + -cyte (“cell”)
histiocyte (plural histiocytes)