Leukocyte apoptosis in whole blood involves platelet-dependent coaggregation.
BACKGROUND
Activated leukocytes and platelet-leukocyte interaction are involved in the pathogenesis of thrombotic and inflammatory events. Because apoptosis is a prerequisite for the successful resolution of an inflammatory response, we investigated the amount of apoptotic peripheral blood leukocytes (PBLs) in whole blood and their possible functional relation with the platelet-leukocyte interaction by a flow cytometric assay using APO 2.7 antibody for the detection of apoptosis


METHODS
Thirty healthy subjects volunteered for the study. PBL apoptosis in seven volunteers was induced by phorbol 12-myristate 13-acetate or while standing at rest.


RESULTS
Apoptosis was observed in all types of leukocytes (0.7% neutrophils, 1.5% monocytes, and 0.3% lymphocytes). Apoptosis was found predominantly in platelet and leukocyte coaggregates (<1% of nonaggregated leukocytes vs. 9% of platelet and leukocyte coaggregates). This phenomenon was even more pronounced after induction of leukocyte apoptosis in vitro (66% of platelet and leukocyte coaggregates).


CONCLUSIONS
Apoptosis and platelet-leukocyte interaction seemed to be closely related phenomena, and apoptotic leukocytes seemed to trigger adhesion and, hence, activation of platelets. Because platelet-leukocyte interaction is involved in the pathogenesis of thrombotic events, apoptotic leukocytes may constitute an additional prothrombotic trigger.
Hartz
S
S
German Diabetes Research Institute, Heinrich-Heine-University, Duesseldorf, Germany.
Menart
B
B
Tschoepe
D
D
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001792:Blood Platelets / Q000502:physiology*; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010974:Platelet Aggregation; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D013755:Tetradecanoylphorbol Acetate