Selective interactions of lymphocytes with neonatal and adult lacrimal gland tissues

The lacrimal gland is a functional part of the mucosal immune system and is populated by lymphoid cells that begin to appear early in neonatal development. To define the events controlling the accumulation of these cells, an in vitro adherence assay was used to investigate the interactions of lymphocyte populations with neonatal and adult lacrimal tissue. It was found that (1) lymphocytes adherence to neonatal lacrimal tissue is significantly enhanced over that seen in adults; (2) the increased binding is caused, in part, by adherence to nonacinar structures in neonatal tissue; (3) binding to both neonatal and adult lacrimal gland tissue is an active process that is observed only with viable lymphocytes; (4) lymphocyte adherence to neonatal and adult lacrimal gland tissues is differentially affected by metabolic and cytoskeletal inhibitors; and (5) attachment appears to require the presence of Ca++, a lymphocyte surface protein, and may involve target tissue carbohydrate recognition. These findings suggest that the initial accumulation of lymphocytes in the neonatal lacrimal gland results from a generalized enhanced binding capacity of the developing tissue and that the preferential binding of certain populations (thoracic duct and mesenteric lymph node lymphocytes) to acinar cells maintains the pool in the adult lacrimal gland.