Platelets enhance lymphocyte adhesion and infiltration into arterial thrombus

Area of Science:

• Immunology
• Hematology
• Cardiovascular Biology

Background:

• Lymphocytes are key players in atherosclerotic lesions.
• The precise mechanisms facilitating lymphocyte infiltration into the arterial wall remain incompletely understood.

Purpose of the Study:

• To investigate the role of platelets in promoting lymphocyte adhesion and infiltration into the arterial wall under flow conditions.
• To identify the molecular mechanisms underlying platelet-mediated lymphocyte recruitment.

Main Methods:

• Perfusion of human blood through a collagen-coated flow chamber at varying shear rates.
• Assessment of lymphocyte adhesion in platelet-depleted versus platelet-containing blood.
• Inhibition studies using blocking agents for P-selectin, CD40L, and GPIIb/IIIa.
• Evaluation in a mouse model of FeCl3-induced arterial thrombosis.

Main Results:

• Platelets markedly enhanced lymphocyte adhesion, increasing deposition significantly at arterial shear rates.
• Platelet-dependent lymphocyte adhesion was inhibited by P-selectin, CD40L, and GPIIb/IIIa blocking agents.
• Lymphocyte infiltration into arterial thrombi in a mouse model was abolished by GPIIb/IIIa inhibition.

Conclusions:

• Platelets actively support lymphocyte adhesion under arterial flow conditions.
• This interaction involves multiple adhesion molecules and is selective among lymphocyte subsets.
• Platelets likely play a critical role in recruiting circulating lymphocytes to sites of arterial injury.