Conjugates of B cells and platelet microparticles in the human peripheral blood

Background: Activated platelets shed microparticles (MPs) in vivo and certainly in vitro under storage. Like platelets, platelet-derived MPs contribute to hemostatic and inflammatory responses. We sought to determine the interactions between platelet MPs and peripheral B lymphocytes in the healthy blood circulation to propose a possible role for platelet MPs in the functioning of B cells. Materials and Methods: An enzyme-linked immunosorbent assay (ELISA) was established to determine the normal interactions between human peripheral blood B lymphocytes and platelet MPs. B cells were isolated and bound to the wells of microtiter plates using coated anti-CD19. Then the presence of attached MPs was surveyed. Also, platelet MPs were separated from human platelet concentrates and applied to confirm the new binding capacities of B cells for these microvesicles. Results: Platelet MPs were recognized in the wells of ELISA in which only B cells were isolated. So MPs were bound with peripheral blood B cells. Furthermore, using this method, the role of CD40/ CD40L interaction was displayed for the binding. Conclusion: It seemed that the binding of platelet MPs to B cells normally took place in vivo and a percent of B cells circulate in blood in connection with platelet MPs.