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Regular Manuscript

Expression of endothelial selectin ligands on human leukocytes following dive

¹ University of Split Hospital Center
² University of Split School of Medicine
³ University of Zagreb School of Medicine
⁴ Norwegian University of Science and Technology

^* To whom correspondence should be addressed. E-mail: zdujic{at}bsb.mefst.hr.

	Abstract

The fact that impaired endothelial-dependent vasodilatation after scuba diving often occurs without visible changes in the endothelial layer implies its biochemical origin. Since Lewis x (CD15) and sialyl-Lewis x (CD15s) are granulocyte and monocyte carbohydrate antigens recognized as ligands by endothelial selectins, we assumed that they could be sensitive markers for impaired vasodilatation following diving. Using flow-cytometry, we determined CD15 and CD15s peripheral blood mononuclear cells of eight divers, 30 min before and 50 min after a single dive to 54 m for 20 min bottom time. The number of gas bubbles in the right heart was monitored by ultrasound. Gas bubbles were seen in all 8 divers, with the average number of bubbles/cm2 1.9±1.9. The proportion of CD15+ monocytes increased two fold after the dive as well as the subpopulation of monocytes highly expressing CD15s. The absolute number of monocytes was slightly but no significantly increased after the dive, whereas absolute number of granulocytes was markedly elevated (up to 61%). There were no correlations between bubbles formation and CD15+ monocytes expression (r = - 0.56; p = 0.17), as well as with monocytes highly expressing CD15s (r = 0.43, p = 0.29). This study suggests that biochemical changes induced by scuba diving primary activate existing monocytes rather than increase the number of monocytes at a time of acute arterial endothelial dysfunction.

Key Words: scuba diving, endothelial function, monocyte, sialyl-Lewis x, ultrasound