The mucosal adhesion receptor α4β7 integrin is selectively increased in lymphocytes stimulated with lactoglobulin in children allergic to cow's milk

Background: It has been shown in mice that the integrin alpha 4 beta 7 directs the migration of memory T cells into the gut-associated lymphoid tissue. However, little is known about T-cell homing mechanisms in children with food allergies. Objective: We investigated the expression of this and other integrins in children with different manifestations of cow's milk allergy (urticaria, atopic dermatitis, and wheezing). Methods: PBMCs were stimulated with beta-lactoglobulin, 1 of the major allergenic proteins in cow's milk, and tetanus toxoid, Integrin expression was studied by flow cytometric analysis after 1 week of culture. Results: We found significantly higher expression of the alpha 4 beta 7 integrin in cells from patients compared with control subjects with no allergies (P = .005) when beta-lactoglobulin was used to stimulate the cells. alpha 4 beta 7 integrin was also expressed at significantly higher levels in beta-lactoglobulin-stimulated cells than in tetanus toroid-stimulated cells (P = .005). The alpha E beta 7 and the alpha 4 beta 1 integrins were not upregulated by allergen stimulation. Most alpha 4 beta 7 integrin-expressing cells were identified as CD4(+) T cells. Conclusion: These results show that alpha 4 beta 7 integrin expression after stimulation with beta-lactoglobulin correlates with the presumptive site of cow's milk sensitization (ie, the gut-associated lymphoid tissue but not with the site of symptoms of cow's milk allergy).