Immunohistochemical and histochemical characterisation of epithelial cells of rabbit lacrimal glands in tissue sections and cell cultures.

The purpose of this study was to establish conditions for isolation and long term culture of acinar cells from the Harderian gland, and superior and inferior lacrimal glands of the rabbit and to compare the in vitro growth patterns of cultured cells from these glands. In order to determine the predominant cell type in the cultures, cells and tissue sections were stained using a variety of antibodies to cytokeratins, smooth muscle actin, and neuron specific enolase. Similarly, PAS and alcian blue histochemistry were used to test for the presence of mucins. The glands were excised and cells isolated using enzymatic digestion and then established in long term culture. Different media and substrata were trialed for suitability. When cultured on uncoated Costar plastic in DMEM/10%FBS, the pattern of cell growth was similar for all glands with distinct phases involving aggregation and migration out from the aggregates before cells died between 20 to 30 days. Immunohistochemical staining indicated that the cultures were of acinar cells with a small percentage of ductal cells. The acinar cells of the lacrimal glands in situ and in vitro stained with antibody MNF116 directed against cytokeratins 5, 6, 8 and 17 but did not stain for antibodies to cytokeratin 18. The reverse staining pattern was true for the Harderian gland. Sections from the white lobe of the Harderian gland showed islets of serous secreting cells which showed positive staining when MNF116 was used. In situ, PAS positive cells were found in a small number of demilunes in the superior and inferior lacrimal glands and also in cells of the intercalated ducts. Surprisingly, in culture nearly all cells, including those isolated form the Harderian gland became PAS positive. In this study we have demonstrated that acinar cells from the Harderian and lacrimal glands of rabbit can be isolated and maintained in culture for 20 to 30 days, and that despite dramatic morphological changes, these cells retain their distinctive phenotype as indicated by antibody staining to specific cellular structural proteins such as cytokeratins and actin. However, the cultured cells also begin to produce mucins as indicated by PAS staining.