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.

Introduction: 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.
Objectives: 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.
Patients and Methods: 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.
Results: 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.
Conclusions: 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.