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CD Markers

CD45RA


Reviewers: Nat Pernick, M.D., (see Reviewers page)
Revised: 28 January 2011, last major update January 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

General
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● Marker of naive T cells

Terminology
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● Also called protein tyrosine phosphatase receptor type C

Physiology
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● CD45 isoforms [functionally similar proteins with similar but not identical amino acid sequence], including CD45A, are generated by alternative mRNA splicing of exons 4 (CD45RA), 5 (CD45RB) and 6 (CD45RC), leading to changes in the extracellular domain of the molecule (J Exp Med 1987;166:1548)
● CD45RA+ T regulatory cells are converted to CD45RO+ T regulatory cells after activation (J Immunol 2010;184:4317)
● High molecular weight transmembrane protein with intrinsic tyrosine phosphatase activity
● Heavily glycosylated, and expressed at high levels on nucleated hematopoietic cells

Diagrams
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Subsets of T cells

Clinical features
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● Cord blood has higher percentage of CD45RA helper T cells than adult blood (Am J Clin Path 1996;105:38)
● In adults, CD45RA+ cells may prevent autoimmune disease (Blood 2006;107:2830)
● Reduced numbers of CD45RA+ CD4+ T cells are associated with children with biliary atresia (Transplant Proc 2003;35:3026);primary biliary cirrhosis (Scand J Gastroenterol 2003;38:421), fetal distress (Biol Neonate 2004;85:61) and preeclampsia (Am J Obstet Gynecol 2002;187:889)

Uses
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● Differentiate naive T cells (CD45RA+) from memory T cells (CD45RO+), but not in adult allogeneic hematopoietic cell transplant recipients (Bone Marrow Transplant 2003;32:609)

Micro images
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Left: normal lymph node (B cells are positive, most T cells are negative); right: tonsil

Positive staining - normal
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● B cells, NK cells, naive/resting T cells (those not exposed to antigens), medullary thymocytes, plasmacytoid dendritic cells (Am J Pathol 2001;159:237)

Positive staining - disease
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Hematologic malignancies
● B cell lymphomas (most), hairy cell leukemia (Hum Pathol 1992;23:172)
● CD8+ primary cutaneous T cell lymphoma (Am J Pathol 1999;155:483)
● CD4(+) CD56(+) lineage-negative malignancies (Am J Surg Pathol 2005;29:1274)
● Progressive transformation of germinal centers
● Reed-Sternberg cells in lymphocyte predominant Hodgkin’s lymphoma (Am J Surg Pathol 1999;23:27)

Other
● Autoimmune lymphoproliferative syndrome (Am J Pathol 1998;153:1541)
● Effector memory T cells in lesional epidermis (Am J Pathol 2002;161:1337)
● CD4+ memory T cells after bone marrow grafts (Eur J Immunol 1999;29:3987)
● Terminally differentiated CD8+ memory T cells (Arthritis Res Ther 2003;5:R91)

Negative staining
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● Basophils, endothelial cells, Langerhans cells, memory T cells (usually), most T cell lymphomas, most plasma cell neoplasms

End of CD Markers > CD45RA


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