Objective: To investigate the significance of circulating adhesion molecules associated with leucocyteendothelial cell interactions in asthma, serum levels of soluble E (sE)-selectin, soluble P (sP)-selectin, soluble L (sL)-selectin, and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured in mild, moderate and severe asthma. Method: Serum levels of sE-selectin, sP-selectin, sLselectin, and sVCAM-1 were measured in 32 women with asthma and 30 healthy donors using an enzymelinked immunosorbent assay method. Twenty patients were suffering from severe asthma, and 12 from mild/moderate asthma. Results: Serum sE-selectin and sVCAM-1 levels from patients with asthma were significantly higher than those observed in healthy donors (p < 0.01). The levels of sP-selectin were the same as those of controls. The level of sE-selectin exhibited an important increase in the severe asthmatic patients compared with mild/moderate asthma (p < 0.01). The sVCAM-1 level was increased in severe asthma when compared with healthy controls. There was no correlation between the levels of soluble selectins and the age of the patients. A significant correlation was found between sE-selectin and sVCAM-1 levels. Conclusion: These data indicate that circulating soluble forms of the selectins may have different kinetics during the clinical course of asthma, suggesting that they may reflect different inflammatory pathways in severe asthma. Both sVCAM-1 and sE-selectin may be useful immunological markers for monitoring disease activity in asthma.Key words: Asthma, Inflammation, Selectins IntroductionAdherence of leucocytes to endothelial cells (EC) is a primordial event in the sequence of inflammatory response. Specific cell adhesion molecules, expressed on the surface of leucocytes and/or EC, have been identified. As an initial event during inflammation, leucocytes in the blood stream roll along EC with loose contact, mediated by E-selectin, P-selectin and L-selectin. 1 In the inflammation phase, activation of leucocyte integrins occurs with expression of immunoglobulin-like adhesion proteins on EC, including intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 (VCAM-1). The leucocytes that are tightly bound to EC then migrate into the subendothelial tissue. Soluble forms of these adhesion molecules are released in circulation. Serum levels may be increased in several inflammatory diseases, and particularly in asthma. These circulating forms may be biologically active. 2 Asthma is known as a bronchial chronic inflammatory disorder. 3 Immunological abnormalities during asthma are characterized by marked activation of the immune system, leading to increased cytokine production by activated effector cells and the induction of antigen expression on EC. 4 The factors modulating the activation and recruitment of circulating inflammatory cells to the lung remain partially unknown, but an early step in this process is the interaction of adhesion molecules on circulating cells with those on EC. 5 Severe asthma is supposed t...