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Immunopathogenesis of vernal keratoconjunctivitis
A M Abu el-Asrar1, K Geboes, K F Tabbara
1Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
Insights
Vernal keratoconjunctivitis (VKC) involves complex immune responses, with increased adhesion molecules promoting inflammatory cell recruitment. This study analyzes immune cell distribution and adhesion molecule expression in VKC conjunctival tissues.
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- Vernal keratoconjunctivitis (VKC) is a severe allergic eye disease.
- The immunopathogenesis of VKC involves complex immune mechanisms.
- Adhesion molecules play a crucial role in inflammatory cell trafficking.
Purpose of the Study:
- To analyze the in situ distribution of immune cells in VKC conjunctival biopsies.
- To investigate the expression and distribution of adhesion molecules in normal and VKC conjunctiva.
- To elucidate the role of adhesion molecules in VKC pathogenesis.
Main Methods:
- Immunohistochemical techniques were employed.
- A panel of monoclonal and polyclonal antibodies was used.
- Analysis of immune cell distribution and adhesion molecule expression.
Main Results:
- VKC conjunctiva showed distinct immune cell components, including IgE-mediated, humoral, and cell-mediated mechanisms.
- Significant upregulation of intercellular adhesion molecule-1 (ICAM-1), lymphocyte function associated antigen-1 (LFA-1), intercellular adhesion molecule-3 (ICAM-3), and very late activation antigen-4 (VLA-4) was observed in VKC.
- Endothelial leukocyte adhesion molecule-1 (ELAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were induced in VKC vascular endothelium.
- ICAM-1 expression increased on basal epithelial cells and vascular endothelium.
- LFA-1 and ICAM-3 were expressed on most infiltrating mononuclear cells.
- VLA-4 was expressed on approximately 25% of stromal mononuclear cells.
Conclusions:
- Increased expression of adhesion molecules in VKC facilitates inflammatory cell recruitment via blood vessels.
- Adhesion molecules mediate crucial cell interactions, including lymphocyte-antigen presenting cell and lymphocyte-epithelial cell interactions.
- These findings highlight the complex immunopathogenesis of VKC and the role of adhesion molecules in disease progression.
Abstract:
We have analyzed the in situ distribution of immune cells in the conjunctival biopsy specimens obtained from patients with active vernal keratoconjunctivitis (VKC). We used immunohistochemical techniques and a panel of monoclonal and polyclonal antibodies. Our data point to a complex immunopathogenesis of the disease. Distinct components involved in IgE-mediated immune mechanisms, as well as humoral and cell mediated immune mechanisms were detected in the conjunctival tissues. In addition, we investigated the presence and distribution of adhesion molecules. In the normal conjunctiva, intercellular adhesion molecule-1 (ICAM-1) was expressed only on the vascular endothelium, lymphocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-3 (ICAM-3) on epithelial and stromal mononuclear cells, and very late activation antigen-4 (VLA-4) on a few stromal mononuclear cells. Endothelial leukocyte adhesion molecule-1 (ELAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression was not detected. In VKC a marked increase of all these antigens was observed. Strong ICAM-1 expression was induced on the basal epithelial cells, and vascular endothelium. Furthermore, about 30% of the stromal mononuclear cells expressed ICAM-1. LFA-1 and ICAM-3 were expressed on the majority of infiltrating mononuclear cells. VLA-4 expression was noted on about 25% of the stromal mononuclear cells. ELAM-1 and VCAM-1 were induced on the vascular endothelial cells. Our results suggests that increased expression of adhesion molecules in VKC promotes the recruitment of inflammatory cells through blood vessels and the cell interaction between lymphocytes and antigen presenting cells, among lymphocytes, as well as between lymphocytes and epithelial cells.