The Specificity of Adhesive Interactions between Rat Lymphocytes and Salivary Gland Epithelia

Salivary immune responses depend on localization of immunocytes in salivary glands. We tested effects of anti-adhesion molecule antibodies and several ligand analogs onin vitroadherence of rat thoracic duct lymphocytes (TDL) to parotid and submandibular gland sections. While TDL adherence to both tissues was markedly decreased by anti-L-selectin mAbs, binding ability after removal of L-selectin by chymotrypsin or PMA suggested that other adhesion systems were involved. Integrin involvement in parotid interactions was indicated by inhibitory effects of anti-HEBFPP, LFA-1, ICAM-1, and α4integrin antibodies as well as by the PMA-enhanced adherence. Anti-Thy-1 partially inhibited TDL binding to parotid gland, and anti-CD44 partially inhibited submandibular binding. The majority of salivary gland-bound TDL were sIg+B cells. FACS analysis showed differences in parotid and submandibular endogenous lymphocyte adhesion molecule expression with greater percentages of L-selectin, HEBFPP, α4integrin, LFA-1, ICAM-1, CD44, and Thy-1-positive cells present in parotid gland. While precise roles of known or novel adhesion molecules in salivary gland lymphocyte retention are not clear, these data suggest that selectins (parotid, submandibular), integrins (parotid), Thy-1 (parotid), and CD44 (submandibular), as well as other unidentified molecules, are involved.