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.