Platelet surface p-selectin, platelet-granulocyte heterotypic aggregates, and plasma-soluble p-selectin during plateletpheresis.

Abstract

Plateletpheresis components have been shown to contain p-selectin-positive platelets after collection and storage. P-selectin mediates binding of activated platelets to granulocytes and monocytes. This study was undertaken to assess platelet activation, granulocyte activation, platelet-granulocyte heterotypic aggregate formation, and the plasma-soluble p-selectin level during plateletpheresis performed on a particular instrument (MCS+, Haemonetics). Flow cytometry was used to assay platelet surface p-selectin, granulocyte iC3b receptor, and platelet-granulocyte aggregates in the platelet component, residual blood in the disposable polycarbonate bowl of the MCS+, and in the donor blood with and without the addition of in vitro agonists before, during, and after plateletpheresis. The plasma-soluble p-selectin levels in the platelet component, disposable bowl, and donor venous blood were measured by an enzyme-linked immunosorbent assay. Levels of p-selectin-positive platelets, activated granulocytes, and platelet-granulocyte aggregates were greater in the disposable bowl than in the preapheresis donor blood. Levels of p-selectin-positive platelets, activated granulocytes, and platelet-granulocyte aggregates in the postapheresis donor blood were similar to those in the preapheresis donor blood. The platelet components contained no activated granulocytes or detectable platelet-granulocyte heterotypic aggregates, and only about 10-percent activated platelets. The plasma-soluble p-selectin level in the platelet component was significantly greater than that in the preapheresis donor blood, the residual blood in the disposable bowl, or the postapheresis donor blood. Measurements of platelet surface p-selectin, platelet-granulocyte heterotypic aggregates, and plasma-soluble p-selectin can be used to detect platelet activation during plateletpheresis.