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T6-positive Langerhans cells in diseased corneas
1Department of Ophthalmology, University of Innsbruck, Austria.
Insights
Corneal Langerhans cells (LC) can express T6 antigen in certain diseases, challenging the idea they are inactive. This antigen expression may be crucial for their immune function in conditions like corneal allograft rejection.
Area of Science:
- Immunology
- Ophthalmology
- Cell Biology
Background:
- Normal corneal Langerhans cells (LC) typically lack T6 antigen, unlike those in other tissues.
- Previous studies suggested corneal LC might be a distinct, inactive subpopulation due to inability to express T6 antigen in culture.
Purpose of the Study:
- To investigate the presence and expression of T6 and HLA-DR antigens on corneal Langerhans cells (LC) in various corneal diseases.
- To determine if corneal LC can express T6 antigen in pathological conditions.
Main Methods:
- Analysis of 62 human corneas from patients with diverse corneal diseases.
- Immunohistochemical detection of T6 and HLA-DR antigens on LC in central and pericentral corneal epithelium.
Main Results:
- T6- and HLA-DR-positive LC were found in corneas with epidermalization after alkali burns, at densities comparable to normal epidermis.
- T6- and HLA-DR-positive LC were also detected in corneas affected by chronic herpetic stromal keratitis, zoster keratitis, allograft rejection, and bacterial ulcers.
Conclusions:
- Corneal Langerhans cells (LC) can express T6 antigen in response to disease states, indicating they are not inherently inactive.
- The induction of T6 antigen on corneal LC may enhance their antigen-presenting capabilities, particularly relevant in corneal allograft rejection and other inflammatory conditions.
Abstract:
Langerhans cells (LC) in normal human corneas (with the exception of newborns) lack thymocyte antigen T6, a highly specific marker for noncorneal LC. Because corneal LC could not be induced to express T6 antigen when cultured with various cytokines including interleukin-1 (shown to modulate T6 expression on gingival LC), some authors assume that corneal LC may represent a distinct LC subpopulation that is innately inactive. In this study, 62 corneas from patients with various corneal diseases were investigated for the presence of T6 and histocompatibility antigen HLA-DR on LC in the central and pericentral epithelium. Both T6- and HLA-DR-positive LC at a high density similar to that observed in normal epidermis could be detected in the epithelium of five corneas with epidermalization after alkali burns. Furthermore T6- and HLA-DR-positive LC at smaller densities also were detected in corneas from patients with chronic herpetic stromal keratitis, zoster keratitis, chronic allograft rejection, and bacterial corneal ulcers. Although the functional significance of T6 expression on corneal LC remains to be determined, the induction of T6 antigen on corneal LC may represent an important event for the antigen-presenting function of these cells in various corneal diseases including corneal allograft rejection.