CD1
Encyclopedia
For the album by Throbbing Gristle, see CD1 (album)
CD1 (cluster of differentiation
1) is a family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are related to the class I MHC molecules, and are involved in the presentation of lipid
antigens to T cells. However their precise function is unknown.
CD1a, CD1b and CD1c (group 1 CD1
molecules) are expressed on cells specialized for antigen presentation.
CD1d
(group 2 CD1) is expressed in a wider variety of cells.
CD1e is an intermediate form, expressed intracellularly, the role of which is currently unclear.
molecules have been shown to present foreign lipid antigens, and specifically a number of mycobacterial cell wall components, to CD1-specific T cells.
Group 2 CD1 molecules activate a group of T cells, known as Natural killer T cell
s because of their expression of NK surface markers such as CD161. Natural Killer T (NKT) cells are activated by CD1d-presented antigens, and rapidly produce Th1 and Th2 cytokines, typically represented by interferon-gamma and IL-4 production.
The group 2 (CD1d) ligand alpha-galactosylceramide is currently in phase I clinical trials for the treatment of advanced non-hematologic cancers.
s, but not on mature T cells. This often remains true in neoplastic cells from these populations, so that the presence of CD1 antigens can be used in diagnostic immunohistochemistry
to identify some thymoma
s and malignancies arising from T cell precursors. CD1a, in particular, is a specific marker for Langerhans cell
s, and can therefore also be used in the diagnosis of Langerhans cell histiocytosis
. Other conditions that may show CD1 positivity include myeloid leukaemia and some B cell lymphoma
s.
lack the group 1 CD1 molecules, and instead have 2 copies of CD1d
. Thus, mice have been used extensively to characterize the role of CD1d and CD1d-dependent NKT cells in a variety of disease models.
It has recently been shown that cows lack the group 2 CD1 molecules, and have an expanded set of group 1 CD1 molecules. Because of this and the fact that cows are a natural host of Mycobacterium bovis
, a pathogen in humans as well, it is hoped that studying cows will yield insights into the group 1 CD1 antigen-presenting system.
CD1 (cluster of differentiation
Cluster of differentiation
The cluster of differentiation is a protocol used for the identification and investigation of cell surface molecules present on white blood cells, providing targets for immunophenotyping of cells...
1) is a family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are related to the class I MHC molecules, and are involved in the presentation of lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
antigens to T cells. However their precise function is unknown.
Types
CD1 glycoproteins can be classified primarily into two groups which differ in their lipid anchoring.CD1a, CD1b and CD1c (group 1 CD1
Group 1 CD1
Group 1 CD1 is a subset of CD1 which is expressed on cells specialized for antigen presentation.Types include:, also known as RT4 and HTA1., also known as BDCA-1...
molecules) are expressed on cells specialized for antigen presentation.
CD1d
CD1d receptor
CD1d is a member of the CD1 family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are related to the class I MHC molecules, and are involved in the presentation of lipid antigens to T cells...
(group 2 CD1) is expressed in a wider variety of cells.
CD1e is an intermediate form, expressed intracellularly, the role of which is currently unclear.
Group 1
Group 1 CD1Group 1 CD1
Group 1 CD1 is a subset of CD1 which is expressed on cells specialized for antigen presentation.Types include:, also known as RT4 and HTA1., also known as BDCA-1...
molecules have been shown to present foreign lipid antigens, and specifically a number of mycobacterial cell wall components, to CD1-specific T cells.
Group 2
The natural antigens of group 2 CD1 are not well-characterized, but a synthetic glycolipid, alpha-galactosylceramide, originally isolated from a compound found in a marine sponge, has strong biologic activity.Group 2 CD1 molecules activate a group of T cells, known as Natural killer T cell
Natural Killer T cell
Natural killer T cells are a heterogeneous group of T cells that share properties of both T cells and natural killer cells. Many of these cells recognize the non-polymorphic CD1d molecule, an antigen-presenting molecule that binds self- and foreign lipids and glycolipids...
s because of their expression of NK surface markers such as CD161. Natural Killer T (NKT) cells are activated by CD1d-presented antigens, and rapidly produce Th1 and Th2 cytokines, typically represented by interferon-gamma and IL-4 production.
The group 2 (CD1d) ligand alpha-galactosylceramide is currently in phase I clinical trials for the treatment of advanced non-hematologic cancers.
Diagnostic relevance
CD1 antigens are expressed on cortical thymocyteThymocyte
Thymocytes are hematopoietic progenitor cells present in the thymus. Thymopoiesis is the process in the thymus by which thymocytes differentiate into mature T lymphocytes. The primary function of thymocytes is the generation of T lymphocytes . The thymus provides an inductive environment, which...
s, but not on mature T cells. This often remains true in neoplastic cells from these populations, so that the presence of CD1 antigens can be used in diagnostic immunohistochemistry
Immunohistochemistry
Immunohistochemistry or IHC refers to the process of detecting antigens in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues. IHC takes its name from the roots "immuno," in reference to antibodies used in the procedure, and...
to identify some thymoma
Thymoma
Thymoma is a tumor originating from the epithelial cells of the thymus. Thymoma is an uncommon tumor, best known for its association with the neuromuscular disorder myasthenia gravis. Thymoma is found in 15% of patients with myasthenia gravis. Once diagnosed, thymomas may be removed surgically...
s and malignancies arising from T cell precursors. CD1a, in particular, is a specific marker for Langerhans cell
Langerhans cell
Langerhans cells are dendritic cells of the skin and mucosa, and contain large granules called Birbeck granules. They are present in all layers of the epidermis, but are most prominant in the stratum spinosum. They also occur in the papillary dermis, particularly around blood vessels, as well as...
s, and can therefore also be used in the diagnosis of Langerhans cell histiocytosis
Langerhans cell histiocytosis
Langerhans cell Histiocytosis is a rare disease involving clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes...
. Other conditions that may show CD1 positivity include myeloid leukaemia and some B cell lymphoma
Lymphoma
Lymphoma is a cancer in the lymphatic cells of the immune system. Typically, lymphomas present as a solid tumor of lymphoid cells. Treatment might involve chemotherapy and in some cases radiotherapy and/or bone marrow transplantation, and can be curable depending on the histology, type, and stage...
s.
In cows and mice
MiceMICE
-Fiction:*Mice , alien species in The Hitchhiker's Guide to the Galaxy*The Mice -Acronyms:* "Meetings, Incentives, Conferencing, Exhibitions", facilities terminology for events...
lack the group 1 CD1 molecules, and instead have 2 copies of CD1d
CD1d receptor
CD1d is a member of the CD1 family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are related to the class I MHC molecules, and are involved in the presentation of lipid antigens to T cells...
. Thus, mice have been used extensively to characterize the role of CD1d and CD1d-dependent NKT cells in a variety of disease models.
It has recently been shown that cows lack the group 2 CD1 molecules, and have an expanded set of group 1 CD1 molecules. Because of this and the fact that cows are a natural host of Mycobacterium bovis
Mycobacterium bovis
Mycobacterium bovis is a slow-growing , aerobic bacterium and the causative agent of tuberculosis in cattle...
, a pathogen in humans as well, it is hoped that studying cows will yield insights into the group 1 CD1 antigen-presenting system.