Comparative effect of haemodynamic variables and rheological properties of the blood on the margination and adhesion of leukocytes and platelets

Watts, Tim (2010). Comparative effect of haemodynamic variables and rheological properties of the blood on the margination and adhesion of leukocytes and platelets. University of Birmingham. Ph.D.

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Abstract

The work in this thesis used an in vitro flow system, which incorporated a capillary viscometer, to systematically determine the effects that haemodynamic variables, or rheological properties of the perfused, fluorescently-labelled blood, had on the behaviour of leukocytes and platelets. By varying shear rate and stress, blood haematocrit, and aggregation and deformability of red cells, we obtained evidence that leukocyte adhesion was dictated by the number of free-flowing cells 'marginated' near the vessel wall and the force experienced by their initial adhesive bonds. Platelet adhesion was dependent on the velocity of the free-flowing cells near the vessel wall and the force experienced by the platelets once adhered. In contrast to leukocytes, variation in platelet adhesion appeared less dependent on variation in the number of free-flowing cells near the vessel wall, but dictated more by the width of the peripheral plasma layer; a thinner plasma layer promoting more efficient platelet adhesion. Overall, this thesis provides evidence that the differential margination and adhesion of leukocytes and platelets is largely a result of the difference in their size. Thus, it seems that the sizes of RBC, leukocytes and platelets are all adapted to provide efficient immune and haemostatic responses in different regions of the circulation.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):