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- Mircheff, A K, et al.
(author)
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Class II antigen expression by lacrimal epithelial cells. An updated working hypothesis for antigen presentation by epithelial cells
- 1991
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In: Investigative Ophthalmology and Visual Science. - 0146-0404 .- 1552-5783. ; 32:8, s. 2302-2310
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Journal article (peer-reviewed)abstract
- It has been suggested that aberrant expression of Class II histocompatibility antigens (HLA) is involvedin T cell activation and leads to autoimmunity. Although Class II antigen expression was foundin various nonlymphoid tissues, including salivary glands, its expression on lacrimal epithelial cells hasnot been reported. In this study, 12 cadaver lacrimal glands were analyzed for HLA-DR and for thenumbers and distributions of T suppressor cells (Ts), T helper cells (Th), B cells, and macrophages.None of these cases exhibited the high numbers of inflammatory cells, tissue damage, and fibrosischaracteristic of Sjogren's syndrome. The HLA-DR-positive epithelial cells were detected in ten cases;they represented from less than 1% to more than 70% of the epithelial cells. In these ten positive cases,there were greater numbers of T cells per millimeter squared (229 ± 94 [mean ± the standard error ofthe mean]) than in the two HLA-DR-negative cases (37 ± 1 [mean ± range]). Three lacrimal glandspecimens tested were negative for immunoglobulin (Ig) G-bearing B cells, and two of the three specimenstested had IgA-bearing cells. Acinar cells were isolated from rat and rabbit lacrimal glands andcultured overnight in serum-free media supplemented with several potential mediators of Class IIantigen expression: interferon-7, carbachol, or isoproterenol. Freshly isolated cells did not expressClass II antigens at detectable levels, but in most experiments, they began to express the antigen evenin the absence of putative mediators. In light of results from recent studies of antigen presentation andepithelial cell membrane dynamics, these findings suggest a hypothesis in which Class II antigen-expressingepithelial cells present antigenic peptides that are generated in the intracellular compartmentsin communication with the basal-lateral membrane assembly and recycling pathway.
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