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.
CD1 glycoproteins can be classified primarily into two groups which differ in their lipid anchoring.
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 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.
In cows and mice
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.
- ↑ Zajonc DM, Wilson IA (2007). "Architecture of CD1 proteins". Curr. Top. Microbiol. Immunol. 314: 27-50. PMID 17593656.
- ↑ Sköld M, Behar SM (2005). "The role of group 1 and group 2 CD1-restricted T cells in microbial immunity". Microbes Infect. 7 (3): 544-51. doi:10.1016/j.micinf.2004.12.012. PMID 15777730.
- ↑ Angenieux C, Salamero J, Fricker D, et al (2000). "Characterization of CD1e, a third type of CD1 molecule expressed in dendritic cells". J. Biol. Chem. 275 (48): 37757-64. doi:10.1074/jbc.M007082200. PMID 10948205.
- ↑ Van Rhijn I, Koets AP, Im JS, et al (2006). "The bovine CD1 family contains group 1 CD1 proteins, but no functional CD1d". J. Immunol. 176 (8): 4888-93. PMID 16585584.
Proteins: clusters of differentiation (see also list of human clusters of differentiation)
|1-50||CD1 (CD1a-c, CD1d) - CD2 - CD3 - CD4 - CD5 - CD8 - CD9 - CD10 - CD11 (CD11a, CD11b, CD11c) - CD13 - CD14 - CD15 - CD16 - CD18 - CD19 - CD20 - CD21 - CD22 - CD23 - CD24 - CD25 - CD26 - CD27 - CD28 - CD29 - CD30 - CD31 - CD32 - CD33 - CD34 - CD35 - CD36 - CD37 -CD38 - CD40 - CD43 - CD44 - CD45 - CD46 - CD49 (CD49a, CD49b, CD49c, CD49d)|
|51-100||CD52 - CD53 - CD54 - CD55 - CD56 - CD58 - CD59 - CD61 - CD62 (CD62E, CD62L, CD62P) - CD63 - CD64 - CD66e - CD68 - CD70 - CD71 - CD72 - CD79 - CD80 - CD81 - CD82 - CD83 - CD86 - CD88 - CD89 - CD90 - CD94 - CD95 - CD97 - CD98|
|101-350||CD103 - CD106 - CD114 - CD116 - CD117 - CD118 - CD120 - CD122 - CD130 - CD131 - CD132 - CD133 - CD134 - CD135 - CD137 - CD138 - CD141 - CD142 - CD143 - CD146 - CD147 - CD151 - CD152 - CD153 - CD154 - CD155 - CD162 - CD164 - CD169 - CD184 - CD206 - CD209 - CD257 - CD278 - CD281 - CD282 - CD283 - CD304|
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