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 alpha(4) and beta(2) subunits. OBJECTIVES The aim of this study was to evaluate the expression of alpha(1) and alpha(2) integrin subunits on peripheral blood T cells in asthmatic subjects, because previously we showed evidence that alpha(1)beta(1) and alpha(2)beta(1) integrins may be found on peripheral blood eosinophils in these subjects. In this study, we also analyzed the expression of alpha(4) and beta(1) subunits as a positive reference. PATIENTS AND METHODS Expression of alpha(1), alpha(2), alpha(4), and beta(1) 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 alpha(1) subunit was not present on peripheral blood T cells in the majority of subjects in both study groups. Expression of alpha(2) was detectable on CD8(+) cells in both groups and was increased on CD4(+) in asthmatics. Both types of T cells showed higher expression of alpha(4) and beta(1) in patients with asthma. Expression of alpha(4) was higher on CD8(+) T cells both in asthmatics and controls. CONCLUSIONS Expression of alpha(4) and beta(1) 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 alpha(2) subunit on T cells remains to be elucidated.