Sepsis- and endotoxemia-generated cytokines do not trigger activation of human platelets.
OBJECTIVE
To analyze the effect of cytokines generated in sepsis and endotoxemia (tumor necrosis factor [TNF]-alpha and interleukins [IL]-1beta, -6, and -8) on activation of human platelets and to study the effect of cytokines on platelet activation in the presence of alpha-thrombin, a potent inducer of coagulation and platelet activation generated in sepsis and endotoxemia.


METHODS
flow cytometric study of platelet activation induced by cytokines and/or thrombin in the whole blood and platelet-rich plasma (PRP) of healthy volunteers.


METHODS
Research laboratory in a Canadian hospital.


METHODS
Nine healthy volunteers recruited from laboratory staff.


RESULTS
Venous blood samples were obtained into acid-citrate-dextrose anticoagulant. Whole blood and PRP were diluted with appropriate buffer optimized for analyzing platelet activation by flow cytometry. TNF-alpha, IL-1beta, IL-6, and IL-8 were added to blood or PRP in concentrations ranging from 1 to 100 ng/mL and incubated for 15 mins at 37 degrees C in the presence or absence of a submaximal concentration of human alpha-thrombin (0.025 units/mL). Samples were stained with fluorescent antibodies against markers of platelet activation (P-selectin [CD62], lysosomal protein [CD63], and fibrinogen and von Willebrand factor receptors [CD41 and CD42b, respectively]) and analyzed by flow cytometry. The data obtained show that none of these cytokines trigger activation of resting platelets in whole blood or PRP and do not modulate the effect of thrombin on platelet activation as measured by quantitation of CD62, CD63, and CD42b markers on the platelet surface.


CONCLUSIONS
Cytokines TNF-alpha, IL-1beta, IL-6, and IL-8, which are extensively produced in sepsis and endotoxemia, do not trigger activation of resting human platelets directly or indirectly by mediating processes in white or red blood cells. The cytokines did not affect thrombin-induced platelet activation.
Leytin
Valery
V
Department of Transfusion Medicine, Shuter Wing, Room 2003, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada.
Shakoor
Samantha
S
Mody
Meera
M
Allen
David
D
Garvey
Bernadette
B
Freedman
John
J
D016207:Cytokines / Q000502:physiology*; D019446:Endotoxemia / Q000276:immunology / Q000503:physiopathology*; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000502:physiology; D015850:Interleukin-6 / Q000502:physiology; D016209:Interleukin-8 / Q000502:physiology; D015539:Platelet Activation / Q000276:immunology*; D018805:Sepsis / Q000276:immunology / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
D016207:Cytokines; D007375:Interleukin-1; D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha