BACKGROUND: The role of platelets in @entity32 is recognized but poorly characterized, and little is known of their interaction with leukocytes. However, platelet-leukocyte interactions have been demonstrated in @entity65 , culminating in enhanced leukocyte recruitment. OBJECTIVES: This study was undertaken to assess the possibility and potential role of similar phenomena occurring in @entity748 @entity1 , a @entity19 model of @entity32 , and in vitro adhesion studies. METHODS: @entity748 @entity1 had blood taken at various time points to document the degree of leukocyte activation and the presence of platelet-leukocyte aggregates through FACS analysis before and after allergen exposure. Similar studies were carried out in @entity19 exposed to allergen after previous sensitization, with some groups being selectively depleted of platelets through both an immunologic (antiplatelet antiserum) and nonimmunologic ( @entity1863 ) method. Additionally, lavage fluid and airway tissue were analyzed to assess the degree of pulmonary leukocyte recruitment. The importance of platelets on leukocyte adhesion to the endothelium was then assessed with in vitro incubation of radiolabeled leukocytes in the presence of activated platelets on cultured @entity1 vascular endothelial cells. RESULTS: We have observed circulating platelet-leukocyte aggregates in the blood of allergic @entity748 @entity1 during the allergen-induced late @entity748 response and in sensitized @entity19 after allergen exposure. In platelet-depleted @entity19 infiltration of leukocytes into airways after allergen challenge was significantly reduced and could be restored by means of infusion of platelets from allergic animals, indicating an essential role for platelets in leukocyte recruitment. @entity9536 expression on leukocytes involved in aggregates with platelets, although not on free leukocytes, was upregulated. Furthermore, the presence of autologous platelets augmented the adhesion of @entity1 polymorphonuclear leukocytes to cultured vascular endothelial cells, an effect that was found to be endothelial cell dependent and to involve platelet activation. CONCLUSION: These results suggest that platelet participation in cell recruitment occurs at the level of the circulation and might involve the priming of leukocytes for subsequent adhesion and transmigration into tissues.

Platelets are essential for leukocyte recruitment in XXXX .

@entity748 :: ('MESH:D013224', 'Disease') :: ['asthmatic', 'Asthmatic'] @entity32 :: ('MESH:D007249', 'Disease') :: ['inflammation', 'allergic inflammation'] @entity1 :: ('9606', 'Species') :: ['patients', 'human'] @entity19 :: ('10090', 'Species') :: ['mice', 'murine'] @entity9536 :: ('3684', 'Gene') :: ['CD11b'] @entity1863 :: ('MESH:D002066', 'Chemical') :: ['busulfan'] @entity65 :: ('MESH:D002318', 'Disease') :: ['cardiovascular disease']
@entity32 :: (MESH:D007249,Disease) :: ['allergic inflammation']
