CD1

From Wikipedia, the free encyclopedia

CD1a molecule
Identifiers
Symbol(s)	CD1A CD1
Entrez	909
OMIM	188370
RefSeq	NM_001763
UniProt	P06126
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.

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.

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 CD1are 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.

Mice 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.

The group 2 (CD1d) ligand alpha-galactosylceramide is currently in phase I clinical trials for the treatment of advanced non-hematologic cancers.

[edit] Nomenclature

CD1a is also known as RT4 and HTA1.
CD1c is also known as BDCA-1

[edit] References

CD1a
1. Leonardo Fainboim; M. C. Salamone (Reviewed by Cesar Milstein). CD1a (part of CD1 Family). PROW:Protein Reviews on the Web. Retrieved on August 16, 2005.