Whole Blood Analysis of Leukocyte‐Platelet Aggregates

Abstract In inflammatory and thrombotic syndromes, platelets aggregate with circulating leukocytes, especially monocytes and neutrophils. This leukocyte‐platelet aggregate formation is initiated primarily through platelet surface expression of P‐selectin (CD62P), following activation‐dependent degranulation of α‐granules, binding to its constitutively expressed counter‐receptor, P‐selectin glycoprotein ligand 1 (PSGL‐1), on leukocytes. Monocyte‐platelet aggregates are a more sensitive marker of platelet activation than platelet surface P‐selectin. Detection of leukocyte‐platelet aggregates is relatively simple by whole‐blood flow cytometry. Light scatter and at least one leukocyte‐specific antibody are used to gate the desired population, and the presence of associated platelets is detected by immunostaining for abundant platelet‐specific markers. © 2016 by John Wiley & Sons, Inc.