Endothelial adhesion molecules for nasal-homing T cells in allergy

During the allergic reaction mucosal T cells are activated and a local increase in numbers occurs. In peripheral blood, a concomitant T cell activation and switch towards memory phenotype appears. E-selectin, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 were studied in nasal mucosal biopsies taken during a time-course provocation study, including patients with seasonal allergic rhinitis and healthy controls. Allergic patients were also studied during the natural pollen season with particular attention to the influence of local corticosteroid treatment. Before provocation allergic patients and controls did not differ concerning the expression of endothelial adhesion molecules. However, the epithelial ICAM-1 expression was increased among allergics (P < 0.05). Repetitive allergen provocation induces an increased endothelial expression of VCAM-1 in allergic patients (P < 0.01). Similarly, VCAM-1 expression was increased during the natural pollen season (P < 0.05). Interestingly, the increased VCAM-1 expression was inhibited by the use of local corticosteroids. The present data demonstrate a putative integrin-VCAM-1 mechanism for selective homing of T memory cells to the allergic nasal mucosa and new in vivo effects of local corticosteroid treatment are demonstrated.