In vitro adherence of rat lymphocytes to salivary gland epithelia

Abstract

Glandular mucosal tissues contain lymphocyte populations that contribute to expression of IgA antibodies in external secretions. Interaction of circulating lymphocytes with glandular structures may regulate lymphocyte accumulation. An in vitro assay was used to investigate adhesive interactions between lymphocytes and salivary gland tissues. Thoracic duct lymphocytes (TDL) bound to the serous acinar epithelia of parotid salivary glands and to the mucous tubulo-acinar epithelium of submandibular salivary glands. Lymph node cells and splenocytes adhered to these tissues in lesser numbers and thymocytes bound in negligible numbers. TDL adherence was an active process, being time- and cell dose-dependent and requiring intact membrane as well as cytoskeletal and metabolic function. Calcium was required in each case and binding was mediated by a trypsin-sensitive lymphocyte surface determinant. These findings suggest that the lymphocyte composition of salivary gland tissues is regulated by active lymphocyte interaction with the glandular epithelium.

Lymphocyte adhesive interactions with cultured parotid salivary gland epithelial cells from rats

“…Previous binding studies (11) have demonstrated that viable TDL bind to the acinai-epithelial cells of fixed, cryostat parotid gland sections. The assay used was a modification of the Stamper & Woodruff in vitro binding assay (21), which has been widely use to study adhesive interactions between recirculating lymphocytes and the high endothelial venules of lymph nodes and Peyer's patches.…”

“…A preliminary experiment determined that the density of adherent TDL under these conditions was comparable to their binding to live parotid epithelial cultures at 37°C with no rotation (66 ± 6 vs. 59 ± 13 bound cells per mm", respectively, n=A wells each). Fixation prevented loss of parotid cells from the wells during the assay and subsequent staining steps as well as more closely approximated the procedures used in earlier studies with fixed cryostat sections of parotid tissue (11). The data presented in these studies were, therefore, obtained using fixed cultures.…”

“…The assay was modified from a previously described binding assay which used frozen sections of parotid gland as the target tissue (11). Culture medium was removed and the cells were gently rinsed in the wells with 0.1 M cacodyiate then fixed for 10 min with 3% glutaraldehyde (in cacodyiate).…”

“…Lymphocytes were incubated over fixed parotid gland epithelial cell cultures at 7°C and with 60 rpm rotation, conditions similar to those reported previously to evaluate lymphocyte binding to fixed parotid gland cryosections (11). Nonadherent cells were removed, the wells stained and the lymphocytes bound to acinar cells were counted.…”

“…In vivo studies have established that IgA-positive cells from mucosa-associated lymphoid tissues traffic to, and accumulate in, salivary glands (7). In vitro assays have been used to examine adhesive interactions between lymphocytes and salivary gland tissues (11,13). Adherence was primarily to the acinar epithelial cells of parotid gland ciyosections, required lymphocyte viability and intact metabolic and cytoskeletal function, depended on the presence of calcium ions (11) and predominantly involved B cells (13).…”