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Poster Networking

Vascular Biology, Blood Cells, and Immunothrombosis

PB1396 - Platelet-leukocyte aggregate formation and its correlation with hemostasis and platelet activation in sickle cell disease

Tuesday, June 25, 2024
13:45 – 14:45 ICT
Room: Exhibition Hall
Background: Hypercoagulability is an important characteristic of sickle cell disease (SCD), and its pathophysiology is related to the concomitant activation of hemostasis and innate immunity, in a process known as immunothrombosis. Studies highlight the formation of platelet-leukocyte aggregates as an important process in hemostasis and platelet activation, recently best demonstrated in the context of COVID-19.

Aims: To evaluate the platelet-leukocyte aggregate formation in patients with SCD and explore their relationship with disease severity and activation of hemostasis and platelets.

Methods: Steady-state SCD patients (SS-homozygous, n =23; SC-heterozygous, n =8) were included, in addition to 10 healthy individuals. Platelet-leucocyte aggregate formation was assessed by flow cytometry of peripheral blood. Anti-CD45 (leucocytes), Anti-CD41 (platelet), Anti-CD62P (Selectin P) antibodies were used. FSC (Foward Scatter) and SSC (Side Scatter) were used to separate cell populations.

Results: Platelet-monocyte aggregate showed increase in SCD patients when compared with healthy individuals (Fig 1.A). Platelet-granulocytes aggregates demonstrated increase in SS-SCD patients when compared to healthy individuals (Fig 1.D). The expression of platelet activation (CD62P+) was elevated in SS-SCD patients when compared to SC-SCD patients and healthy individuals, both in monocytes and granulocytes (Fig B, E). Association was observed with platelet-leucocyte aggregates with platelet activation (CD62P), (Fig C, F). Furthermore, correlation was observed between platelet-leukocyte aggregates and parameters of severity and activation of hemostasis, which are described in table 1.

Conclusion(s): Our results demonstrate that platelet-leukocyte aggregates are elevated in SCD, and that the platelet activation marker (CD62P) on leukocytes is increased in homozygous patients (SS-SCD). Although preliminary, there was an association between platelet-monocyte aggregates and markers of platelet and hemostasis activation, especially CD62P, D dimer and VWF.