Platelet subpopulation bearing leukocyte specific antigen and tissue factor

Area of Science:

• Cardiovascular Biology
• Hematology
• Immunology

Background:

• Platelets play a crucial role in hemostasis and thrombosis.
• Leukocyte antigen CD45 is typically found on leukocytes, not platelets.
• Tissue factor (TF) initiates the extrinsic pathway of blood coagulation.

Purpose of the Study:

• To investigate the presence and kinetics of CD45-positive platelets in patients with myocardial infarction (MI).
• To determine the co-expression of tissue factor (TF) on CD45-positive platelets in MI patients.
• To explore the potential origin of CD45-positive platelets in the context of MI.

Main Methods:

• Flow cytometry was used to identify and quantify platelets expressing CD45 and TF.
• Blood samples were collected from MI patients and healthy donors at different time points.

Main Results:

• Platelets expressing CD45 (CD45+) and co-expressing TF (CD45+/TF+) were detected in both MI patients and healthy donors.
• The number of CD45+ and CD45+/TF+ platelets was comparable between MI patients and controls on day 1 post-MI.
• A significant increase in CD45+ and CD45+/TF+ platelets was observed in MI patients 8-12 days after MI onset, reaching up to 5-6% and 2-3% respectively.

Conclusions:

• CD45-positive platelets, some expressing TF, are present in circulation and increase after myocardial infarction.
• The elevated levels of CD45+/TF+ platelets suggest a potential role in the thrombotic complications following MI.
• These CD45+/TF+ platelets may arise from interactions between platelets and leukocytes or leukocyte-derived microparticles.