ADHESION MOLECULES AND LYMPHOCYTE RECRUITMENT IN LYMPHOCYTIC THYROIDITIS, THYROID PAPILLARY CARCINOMA AND PAROTID ADENOLYMPHOMA

Lymphocytic infiltrates are usually present in chronic lymphocytic thy roiditis, thyroid papillary carcinoma and parotid adenolymphoma. We se lected these conditions to investigate the mechanisms of recruitment a nd organization of lymphocytic infiltrates in extranodal tissues. MoAb s in immunoperoxidase were used to identify the expression of ICAM-1 a nd VCAM-1 on endothelial cells (EC), and of their ligands LFA-1 and VL A-4 on lymphocytes and accessory cells. VCAM-1 positive EC were rarely observed in thyroids devoid of lymphocyte infiltration. Conversely, E C in chronic lymphocytic thyroiditis and in papillary carcinoma showed positive immunostaining for VCAM-1 and ICAM-1. These findings were as sociated with the presence of lymphocytes positive for the ligands VLA -4 and LFA-1. The upregulated expression of VCAM-1 on perifollicular c apillaries was co-distributed with an accumulation of VLA-4 positive l ymphocytes. In adenolymphoma, all EC were ICAM-1 positive, whereas the majority of vessels were VCAM-1 negative. Consequently the majority o f lymphoid cells were LFA-1 positive and VLA-4 negative. We suggest th at ICAM-1 and VCAM-1 expression on EC play a role in the recruitment o f lymphocyte infiltration in chronic lymphocytic thyroiditis and capil lary carcinoma. Furthermore, the upregulation of VCAM-1 and VLA-4 in t hyroid reactive and neoplastic conditions may be linked to an immune r esponse possibly related to thyroid tissue antigens.