Recent studies have revealed that eosinophils and eosinophil- derived mediators strongly contribute to the onset of nasal swelling and nasal hyperreactivity. The effect of histamine on the adhesion of endothelial cells to ³⁵S-labeled eosinophils and on eosinophil transendothelial migration was investigated. Human microvascular endothelial cells were isolated and cultured from the mucosa of the inferior turbinates of patients with nasal allergy.
Histamine caused dose- related enhancement of adhesiveness to eosinophils. Incubation of endothelial cells treated with 10^-5M and 10^-4M histamine increased adhesion to eosinophils by a mean of 56.4% (p<0.05) and 66.0% (p<0.05), respectively. When eosinophils were incubated with histamine, they did not induce any increase in adhesion to endothelial cells. Preincubation of endothelial cells with anti-ELAM-1 significantly inhibited histamine- induced adhesion, whereas anti-ICAM-1 and anti-VCAM-1 had no inhibitory effect. Histamine did not increase eosinophil transendothelial migration.
Histamine is known to be vasoactive, mediating vasodilation and plasma extravasation. In addition, the results of this study raise the possibility that histamine promotes eosinophil adhesion to endothelial cells by increasing ELAM-1 molecules on endothelial cells and promotes nasal inflammatory and allergic reactions.