CD42

CD42 is a cluster of differentiation designation used for platelet surface glycoproteins that are part of the glycoprotein Ib-IX-V receptor complex. The CD42 family includes CD42b (GPIb alpha), CD42c (GPIb beta), CD42d (GPIX), and CD42f (GPV). These subunits assemble to form the receptor that mediates platelet adhesion to exposed subendothelial collagen via binding to von Willebrand factor, an essential step in primary hemostasis. The complex enables platelets to tether and roll at sites of vascular injury and supports subsequent activation and aggregation.

The CD42-bearing complex plays a central role in platelet function. Its proper expression and activity are necessary for effective platelet adhesion under high shear conditions, and disruptions can impair hemostasis. Variants or deficiencies of the GPIb-IX-V complex are most prominently associated with Bernard-Soulier syndrome, a rare inherited bleeding disorder characterized by macrothrombocytopenia and mucocutaneous bleeding.

In clinical practice and research, CD42 antibodies are widely used as reagents in flow cytometry and immunoassays to identify platelets, quantify glycoprotein expression, and aid in the diagnosis of platelet function disorders. These reagents help distinguish inherited platelet defects from other causes of thrombocytopenia and can be used to enrich or deplete platelets in experimental workflows.