CD Markers
CD42b
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: CD42b
CD42b
Author: Nat Pernick, M.D.
Topic Completed: 1 December 2010
Minor changes: 2 October 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: CD42b
Table of Contents
Definition / general | Diagrams / tables | Pathophysiology | Case reports | Uses by pathologists | Positive staining - normal | Positive staining - disease | Additional referencesCite this page: Pernick, N. CD42b. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cdmarkerscd42b.html. Accessed January 16th, 2021.
Definition / general
- CD42a-d complex is receptor for von Willebrand factor and thrombin
- Also called platelet GPIb alpha, glycoprotein Ib-alpha
- Mutations are associated with Bernard-Soulier syndrome (giant platelet syndrome, OMIM #231200, Int J Hematol 2002;76:319), a bleeding disorder with thrombocytopenia, prolonged bleeding time and giant platelets
- CD42b mutations also cause platelet type von Willebrand disease, which is known as pseudo-von Willebrand disease (OMIM #177820)
- Reduced levels are associated with bleeding disorders in AML patients (Saudi Med J 2005;26:1095)
- Aspirin induces shedding of CD42d and CD42b from platelets (J Biol Chem 2005;280:39716)
- Various snake venoms induce platelet aggregation via CD42b, including TVMA (Toxicon 2004;44:649, but see Xenotransplantation 2004;11:203-inhibits platelet aggregation), alboluxin (Thromb Haemost 2002;87:692) and bilinexin (Thromb Haemost 2001;86:1277)
- CD42b physiology is part of bacterial virulence factors:
- Streptococcus sanguis, an oral bacteria causing infective endocarditis, adheres to platelets and platelet-fibrin vegetations via CD42b (Br J Haematol 2005;129:101)
- Some strains of H. pylori induce platelet activation mediated by H. pylori-bound vWF interacting with CD42b, which may promote peptic ulcer disease and H. pylori-associated cardiovascular disease (Gastroenterology 2003;124:1846)
Diagrams / tables
Images hosted on other servers:
CD42a-d complex
Interactions
Pathophysiology
- CD42a-d complex (also called glycoprotein Ib-IX-V receptor) is the surface platelet receptor for von Willebrand factor on endothelium (particularly CD42b)
- Endothelial damage exposes vWF, which binds to platelets very quickly despite high shear pressures; this leads to platelet activation, then a change in the platelet GpIIb-IIIa receptor, which allows binding to surface bound fibrinogen and free fibrinogen; this leads to platelet crosslinking and aggregation
- Platelet activation apparently involves disruption of the macromolecular complex of GP-Ib with the platelet glycoprotein IX (GP-IX) and dissociation of GP-Ib from the actin-binding protein
- GPIb alpha (CD42b) and GPIb beta (CD42c) form main part of VWF receptor
- CD42b also binds to thrombospondin-1, a glycoprotein in arteriosclerotic plaques, causing thrombus formation independent of von Willebrand factor (FASEB J 2003;17:1490)
- Platelet receptors are important in understanding thrombus formation (Haematologica 2009;94:700)
Case reports
- Bernard-Soulier disease variant (Arch Pathol Lab Med 2005;129:e214)
Uses by pathologists
- Marker of megakaryocytes and platelets
- Diagnosis of AML-M7; distinguish AML-M7 (CD42b+) from acute myelosis with myelofibrosis (usually CD42b neg, Mod Pathol 2005;18:603)
Positive staining - normal
- Platelets, megakaryocytes and megakaryoblasts
Positive staining - disease
- Blasts in transient myeloproliferative disorder
Additional references
