Apart from the platelet count, MPV is the most commonly measured platelet index.
More directly, one can measure serum levels of platelet factor 4 (PF4), which is released by platelets when they degranulate 20.
Platelet factor 4 (PF4) was measured from α-granules, serotonin was measured from δ-granules, β-hexosaminidase was measured from lysosomes, and platelet-activating factor (PAF) was measured as it was manufactured from platelet lipid membranes.
Platelet activation was assessed by measuring plasma levels of soluble P-selectin and platelet factor 4 (PF4) with a commercially available ELISAs (R&D Systems, Abingdon, United Kingdom).
Consequently, de novo protein expression, for example, of P-selectin (CD62P), on the platelet plasma membrane as well as plasma levels of soluble mediators, for example, β-thromboglobulin (β-TG, CXCL7) and platelet factor 4 (PF4, CXCL4), can be used as a measure of (in vivo) platelet degranulation/activation.
Activated platelets secrete various factors including platelet factor 4, P-selectin and several inflammatory mediators accompanying morphological changes and aggregation40.
Normal platelet factor 4 and β thromboglobulin indicated absent or minimal platelet activation.
Platelet activation was determined by levels of platelet factor 4 and β thromboglobulin.
Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating antibodies that recognize platelet factor 4/heparin (PF4/hep) complexes.
Platelet factor 4, beta-thromboglobulin (betaTG), platelet/endothelial cell adhesion molecule-1, P-selectin, thromboxane B2, 6-ketoprostaglandin F1a, vascular cell adhesion molecule-1, and E-selectin were measured by ELISA.
