Effects of Platelet Microparticles on the Activation of B Cells

Platelets are anucleated fragments derived from megakaryocytes. It has been demonstrated that platelets play a role in hemostasis and innate immunity. In addition, platelets have a CD40 ligand which is an important molecular marker in motivating immune cells. Thus, platelets also have a role in adaptive immunity as seen by their ability to activate B cells. Since human platelet microparticles (MPs) originate from platelets, we have chosen to examine the effects of MPs on B cell activation. Methods: Platelet MPs were isolated from platelet concentrates obtained from the Tehran Blood Transfusion Center. The MPs were co-cultured with B cells isolated from human whole blood with magnetic beads using negative selection. After seven days, the expression of activation markers CD27 and CD86, as well as IgD were evaluated by flow cytometry. Results: In a comparison between test (B cells/MPs) and control (B cells) cells we observed that the expression of activation markers CD27 and CD86 increased during the seven-day co-culture period. However, the expression of IgD antibody decreased. Conclusions: As with platelets, MPs can affect B cell activation during in vitro co- culture.