PLATELET NEUTROPHIL RELATIONS - ROLE OF CATHEPSIN-G

Many in vitro studies have revealed influences on the reactivity of platelets of substances released by neutrophils. This article describes the direct stimulation of platelets by activated neutrophils in their vicinity. In this mechanism, never seen previously, a mediator is released by neutrophils and stimulates platelets (agregation, release of serotonin, movement of intracellular calcium, synthesis of thromboxane). It involves a proteinase present in the alpha granules of neutrophils: cathepsin G. The proteolytic activity of this enzyme is necessary to the biological activity seen and is blocked by alpha-1-antichymotrypsin, englin C, heparin and fraxiparine. This cellular interaction may be effective in vivo in certain pulmonary disorders in which neutrophils and platelets play a role.