Thrombin—Mast cell interactions

Thrombin and IgE antigen induce formation of inositol phosphates by mouse E‐mast cells

“…Alternatively, 1 x lo6 IgE-sensitized cells in TG or calcium-free TG containing 2 mM EGTA were challenged with 75 ng DNP-BSA [l]. The cells were centrifuged at 400 x g at 22"C, and the supernatants and pellets were assayed for either histamine [2] or fi-hexoaminidase [8] and the net percentage release of the preformed mediators was calculated [8].…”

“…The immunological activation secretion response of cultured E-MC by IgE antigen was found to be similar to that induced by thrombin in the release of preformed mediators such as histamine and ,% hexosaminidase [l] and transmembrane activation of adenylate cyclase [2]. However, in contrast to the IgE-mediated activation, stimulation of E-MC by physiological concentration of thrombin did not result in the oxidation of arachidonic acid through the Slipoxygenase pathway [ 11.…”

Mast cell chymase in complex with heparin proteoglycan is regulated by protamine

“…Thrombin has, in addition to its procoagulant activities, a number of properties of potential importance in inflammation, e.g. chemotactic activity [26], mitogenic activity [27] and capacity to induce MC degranulation [28]. Thus, the blocking of chymase-mediated thrombin inactivation may increase the pro-inflammatory effects of generated thrombin, thereby contributing to the adverse effects observed for protamine.…”

Tumour Immunology: Alternative Perspectives

“…Fibrin deposits are found in most tumours [29] and are considered important for the relative inaccessibility of the internal tumour milieu to systemic factors. Aside from its role in coagulation, thrombin is a potent mitogen [48], a chemotactic substance for monocytes/ macrophages [49], an inducer of mast cell degranulation [50], and an inducer of leucocyte adhesion molecules in endothelial cell membranes [51]. It is well established that macrophages produce growth factors such as PDGF [52], colony-stimulating factors [53], and others [54].…”