Thrombin-stimulated platelets selectively bind to monocytes and polymorphonuclear leukocytes in a calcium-dependent manner, but only weakly to lymphocytes.
Thrombin-stimulated platelets selectively bind to monocytes and PMNs via a Ca2+-dependent mechanism, highlighting a specific platelet-leukocyte interaction pathway.
The association of platelets with leukocytes was investigated, using gel-filtered platelets stimulated with thrombin and then fixed with formaldehyde. Evidence is presented that stimulation of gel-filtered platelets with low concentrations of thrombin (0.01 to 0.1 U/mL) induces the expression of surface determinants interacting strongly with monocytes and polymorphonuclear leukocytes (PMNs) but only weakly with lymphocytes. Both monocyte-platelet binding and PMN-platelet binding occurred at 37 degrees C and more intensively at 0 degrees C; it was Ca2+-dependent and was unaffected by the addition of sodium azide. The binding also occurred with the monocytoid cell lines HL 60 and U 937 in exponential growth and was much less two days after induction of terminal differentiation by phorbol myristate acetate (PMA). No other tested cell lines (B cells, T cells, and myeloid cells) bound thrombin-stimulated platelets. Monocyte-derived macrophages kept in culture for one week also exhibited reduced binding of thrombin-stimulated platelets. IgG and fibronectin could be ruled out as ligands that mediate binding.
Jungi et al. (Sat,) reported a other. Thrombin stimulation of platelets was evaluated on Platelet-leukocyte binding. Thrombin-stimulated platelets selectively bind to monocytes and polymorphonuclear leukocytes in a calcium-dependent manner, but only weakly to lymphocytes.