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CD Markers

CD46


Reviewers: Nat Pernick, M.D. (see Reviewers page)
Revised: 22 January 2011, last major update January 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

General
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● Antigen which helps downregulate the immune system

Terminology
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● Also called membrane cofactor protein (MCP), Trophoblast leukocyte common antigen

Physiology
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● Has multiple isoforms, but unlike CD45, they donít appear to have clinical significance
● Cofactor for proteolytic cleavage of C3b and C4b by factor I (J Immunol 2002;168:6298), which prevents inappropriate complement activation, especially via alternative pathway, by limiting formation and function of C3 convertases
● Induces regulatory T cells (Nature 2003;421:388), which suppress immune function by secreting IL-10, and may prevent autoimmunity; various pathogens (see below) appear to exploit this property by binding to CD46 to induce an immunosuppressive phenotype

Clinical features
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● Receptor for adenovirus (various serotypes, J Virol 2005;79:7503), HHV-6 (Cell 1999;99:817, J Biol Chem 2003;278:25964), measles virus (Cell 1993;75:295), Neisseria gonorrhoeae (J Cell Biol 2002;156:951), Streptococcus pyogenes (Infect Immun 2008;76:3951)
● Expression is often increased on tumor cells
● Homozygosity for specific alleles is a high risk factor for some types of recurrent pregnancy loss (Hum Reprod 2006;21:818)
● Mutations predispose to familial hemolytic uremic syndrome atypical type 2 (Proc Natl Acad Sci USA 2003;100:12966)

Uses
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● No significant clinical use by pathologists

Positive staining - normal
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● All cells except erythrocytes and some bone marrow cells

Negative staining
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● Red blood cells

Additional references
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MIM 120920, Springer Semin Immunopathol 2005;27:345

End of CD Markers > CD46


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