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

Abstract Background: It has been shown in mice that the integrin α4β7 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 β-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 α4β7 integrin in cells from patients compared with control subjects with no allergies ( P = .005) when β-lactoglobulin was used to stimulate the cells. α4β7 integrin was also expressed at significantly higher levels in β-lactoglobulin–stimulated cells than in tetanus toxoid-stimulated cells ( P = .005). The αEβ7 and the α4β1 integrins were not upregulated by allergen stimulation. Most α4β7 integrin–expressing cells were identified as CD4 + T cells. Conclusion: These results show that α4β7 integrin expression after stimulation with β-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). (J Allergy Clin Immunol 1999;103:931-6.)