PLATELET LEUKOCYTE INTERACTION - SELECTIVE BINDING OF THROMBIN-STIMULATED PLATELETS TO HUMAN-MONOCYTES, POLYMORPHONUCLEAR LEUKOCYTES, AND RELATED CELL-LINES

  • 1 March 1986
    • journal article
    • research article
    • Vol. 67  (3) , 629-636
Abstract
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.degree. C and more intensively at 0.degree. 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 reducing binding of thrombin-stimulated platelets. IgG and fibronectin could be ruled out as ligands that mediate binding.