title: Thrombin-induced chemotaxis and aggregation of neutrophils.
abstract: Thrombin-induced neutrophil chemotaxis and aggregation were studied using cells isolated from either human or sheep blood. Sheep neutrophils (10(8) cells/ml) exhibited maximum chemotactic migration towards 10(-8)M human alpha-thrombin, 10(-8)M gamma-thrombin (which lacks the fibrinogen site), and 10(-12)MD-Phe-Pro-Arg-CH2-alpha-thrombin (catalytically inactive thrombin). Chemotactic responses of the same magnitude were obtained with human neutrophils (10(8) cells/ml). The chemotactic responses to thrombin were comparable to those obtained with diluted (1:200 v/v) zymosan activated serum (ZAS) and 10(-11)M FMLP. Premixing of the thrombin forms with hirudin in 1:1 stoichiometric amounts abolished the chemotaxis but not chemokinesis Aggregatory responses of human and sheep neutrophils were comparable for ZAS, alpha-thrombin, and gamma-thrombin. The responses of both human and sheep neutrophils to D-Phe-Pro-Arg-CH2-alpha-thrombin were attenuated, indicating that the proteolytic site may be involved in the aggregatory response. The results suggest that thrombin-induced neutrophil chemotaxis and aggregation are mediated by different mechanisms, since chemotaxis is a catalytically independent response whereas aggregation is an active site independent response.
mesh_terms: D000818:Animals; D002449:Cell Aggregation / Q000187:drug effects*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D006801:Humans; D009504:Neutrophils / Q000187:drug effects* / Q000502:physiology; D012756:Sheep; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D013917:Thrombin