Differentiation of platelet-leukocyte conjugate formation by short term exercise

Platelet-leukocyte conjugates are increased in cardiovascular disease, but exercise is also able to trigger platelet-leukocyte formation in healthy subjects. The aim was to investigate the heterogeneity of platelet-leukocyte conjugate formations triggered by short term exercise. 18 healthy non-smokers underwent a 90 second maximal test on a SRM cycle ergometry system and a control experiment. Blood samples were taken after 30 min rest, immediately before and after, 15 min and 1 h after exercise. The different platelet-leukocyte conjugates were detected by flow cytometry via CD45, CD14, CD16, CD41, together with CD62P antibodies for the investigation of platelet activation in the conjugates. In addition, a stimulation of conjugate formation in vitro with 8 microM TRAP-6 was initiated. Immediately after exercise platelet-granulocyte (+24%), and -lymphocyte (+17%) conjugates were increased (p<0.01), while the platelet-monocyte conjugates (+40%) were enhanced (p<0.05) 15 min after exercise. The differentiation after stimulation showed that the regular (CD14(+)16(-); +32%) and mature (CD14(+)16(+); +35%) monocytes were both increased after exercise (p<0.01) but the regular monocytes were preferred (p<0.001) in platelet-monocyte conjugate formation. In addition, these conjugates revealed the highest CD62P expression. Maximal short term exercise is useful for the investigation of platelet-leukocyte formation; e.g., it could be shown, that regular monocytes may be preferred in conjugate formation and that these conjugates revealed the highest CD62P expression.