CD1

CD1a molecule
Identifiers
Symbol	CD1A
Alt. symbols	CD1
Entrez	909
HUGO	1634
OMIM	188370
RefSeq	NM_001763
UniProt	P06126
Other data
Locus	Chr. 1 q22-q23

CD1b molecule
Identifiers
Symbol	CD1B
Alt. symbols	CD1
Entrez	910
HUGO	1635
OMIM	188360
RefSeq	NM_001764
UniProt	P29016
Other data
Locus	Chr. 1 q22-q23

CD1c molecule
Identifiers
Symbol	CD1C
Alt. symbols	CD1
Entrez	911
HUGO	1636
OMIM	188340
RefSeq	NM_001765
UniProt	P29017
Other data
Locus	Chr. 1 q22-q23

CD1d molecule
Identifiers
Symbol	CD1D
Entrez	912
HUGO	1637
OMIM	188410
RefSeq	NM_001766
UniProt	P15813
Other data
Locus	Chr. 1 q22-q23

CD1e molecule
Identifiers
Symbol	CD1E
Entrez	913
HUGO	1638
OMIM	188411
RefSeq	NM_030893
UniProt	P15812
Other data
Locus	Chr. 1 q22-q23

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.

CD1 glycoproteins can be classified primarily into two groups which differ in their lipid anchoring.

CD1e is an intermediate form, expressed intracellularly, the role of which is currently unclear.

Group 1 CD1 molecules have been shown to present foreign lipid antigens, and specifically a number of mycobacterial cell wall components, to CD1-specific T cells.

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 cells 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.

CD1 antigens are expressed on cortical thymocytes, 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 to identify some thymomas and malignancies arising from T cell precursors. CD1a, in particular, is a specific marker for Langerhans cells, 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 lymphomas.

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Wikipedia