Expression of very late activation antigen-1 on intrathyroid lymphocytes in autoimmune thyroid disease.

Very late activation antigen-1 (VLA-1) is a beta 1-integrin implied in interaction with extracellular matrix components. It is expressed by T lymphocytes upon prolonged activation in vitro. In this work we have evaluated VLA-1 expression in thyroid infiltrates and peripheral blood of patients with autoimmune thyroid disease (AITD), by immunofluorescence on dispersed cells and by in situ analysis on frozen tissue sections. The results obtained showed increased proportions of VLA-1 positive lymphocytes in thyroid infiltrates, similarly to that observed with "early" activation antigens. No positivity of thyroid follicular cells was observed. Given the role of the VLA-1 molecule in lymphocyte adhesion, the increased VLA-1 positivity of infiltrating lymphocytes is consistent with intrathyroidal homing of long-term activated cells, possibly relevant to AITD pathogenesis.