ALLERGEN-STIMULATED T-LYMPHOCYTES FROM ALLERGIC PATIENTS INDUCE VASCULAR CELL-ADHESION MOLECULE-1 (VCAM-1) EXPRESSION AND IL-6 PRODUCTION BY ENDOTHELIAL-CELLS

Adhesion of inflammatory cells to endothelium is a critical step for t heir transvascular migration to inflammatory sites. To evaluate the re lationship between T lymphocytes (TL) and vascular endothelium, supern atants from allergen-stimulated TL obtained from patients sensitive to Dermatophagoides pteronyssinus (Dpt) versus healthy subjects were add ed to endothelial cell (EC) cultures. TL were stimulated by autologous -activated antigen-presenting cells (APC) previously fixed in paraform aldehyde to prevent monokine secretion. Two parameters were measured: the expression of adhesion molecule and the production of IL-6. Relate d allergen-stimulated TL supernatants from allergic patients induced a n increase of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) ex pression when supernatants of the control groups (TL exposed to an unr elated allergen or not stimulated or TL obtained from healthy subjects ) did not. E-selectin expression was not modulated whatever the supern atant added to EC culture. IL-6 production by EC was significantly enh anced after activation with related allergen-stimulated TL supernatant s from allergics compared with control supernatants. Induction of VCAM -1 expression was inhibited by adding neutralizing antibodies against IL-4, whereas IL-6 production and ICAM-1 expression were inhibited by anti-interferon-gamma (IFN-gamma) antibodies. Enhanced production of I L-4 and IFN-gamma was detected in related allergen-stimulated TL super natants from allergic subjects compared with the different supernatant s. These data suggest that allergen-specific TL present in the periphe ral blood of allergic patients are of Th1 and Th2 subtypes. Their stim ulation in allergic patients may lead to the activation of endothelial cells and thereby participate in leucocyte recruitment towards the in flammatory site.