Increased expression of α2 (CD49b), α4 (CD49d) and β1 (CD29) integrin subunits on peripheral blood T lymphocytes in clinically stable mild‑to‑moderate persistent asthma

Abstract

Adhesive molecules, particularly selectins and integrins, are critical for the inflammatory cell trafficking from blood to the lungs. Among integrins, the most important for cell infiltration are those containing α₄ and β₂ subunits. The aim of this study was to evaluate the expression of α₁ and α₂ integrin subunits on peripheral blood T cells in asthmatic subjects, because previously we showed evidence that α₁β₁ and α₂β₁ integrins may be found on peripheral blood eosinophils in these subjects. In this study, we also analyzed the expression of α₄ and β₁ subunits as a positive reference. Expression of α₁, α₂, α₄, and β₁ subunits was analyzed by flow cytometry on CD₄+ and CD8+ T lymphocytes obtained from the peripheral blood of 54 clinically stable, asymptomatic, mild-to-moderate persistent asthmatics and 40 healthy controls. The α₁ subunit was not present on peripheral blood T cells in the majority of subjects in both study groups. Expression of α₂ was detectable on CD8+ cells in both groups and was increased on CD4+ in asthmatics. Both types of T cells showed higher expression of α₄ and β₁ in patients with asthma. Expression of α₄ was higher on CD8+ T cells both in asthmatics and controls. Expression of α₄ and β₁ integrin subunits is increased on peripheral blood T cells in patients with asthma, which confirms the preactivation of blood lymphocytes even in stable and asymptomatic disease. The biological role of α₂ subunit on T cells remains to be elucidated.