Abstract
The capacity of inflammatory cells to adhere is critical to inflammatory responses and involves an array of adhesion molecules grouped into distinct families. Intercellular adhesion molecule (ICAM)-1 has recently attracted much interest in view of increasing evidence that it plays a prominent role in allergic diseases such as asthma and rhinitis. Apart from its role in adhesion of inflammatory cells to vascular endothelium, the extracellular matrix and epithelium, ICAM-1 mediates T-cell/T-cell, T-cell/target cell and T-cell/B-cell interactions. ICAM-1 on the surface of T-cells is thought to participate in signal transduction and may thus modulate several functions including activation, proliferation, cytotoxicity and cytokine production. Because ICAM-1 is the receptor for the major group of rhinoviruses, the most important cause of acute asthma attacks, binding of rhinovirus (RV) to ICAM-1 on T-cells may, at least theoretically, modulate their function. We review here the role of ICAM-1 in asthma and focus more specifically on its expression on T-cells. We present evidence for a general increase in ICAM-1 expression in this disease including recent observations of enhanced expression on the surface of T-cells in the airways lumen. Whilst the implications of intercellular adhesion molecule- upregulation in asthma remain to be fully elucidated, its participation in cell trafficking and activation are being considered as a target for treatment. We present here early attempts to interfere with intercellular adhesion molecule-1 as an adhesion molecule involved in cell influx and studies aimed preventing virus-induced exacerbations of asthma in children based on the knowledge that intercellular adhesion molecule-1 is the receptor for rhinoviruses.
