INTERCELLULAR-ADHESION MOLECULE-1 (ICAM-1) AND LEUKOCYTE FUNCTION-ASSOCIATED ANTIGEN-1 (LFA-1) EXPRESSION IN HUMAN EPIRETINAL MEMBRANES

Various histogenetically different cell types such as macrophages, retinal pigment epithelial cells, glial cells, and fibroblasts are involved in the formation of epiretinal membranes. In the development of such multicellular tissues, cellular adhesion molecules (CAMs) are necessary for cell migration, proliferation, and localization, and the transfer of information between the cells. We investigated the expression of the intercellular adhesion molecule 1 (ICAM-1) and the leukocyte function-associated antigen 1 (LFA-1) in frozen sections of epiretinal membranes in proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR), macular pucker, and recurrent membranes after intraocular silicone oil tamponade using the indirect immunoperoxidase method. ICAM-1 forms a receptor-ligand pair with LFA-1 and is involved in a number of significant cellular interactions, e.g. in providing dynamic position-specific information to guide lymphocyte and leukocyte localization in the immune response. ICAM-1 is a member of the immunoglobulin gene super-family of CAMs. LFA-1 is a member of the integrin family of cell membrane receptors. It mediates a wide range of lymphocyte, monocyte, natural killer cell, and granulocyte interactions with other cells in immunity and inflammation, and it is a receptor for ICAM-1. The LFA-1 interaction with its ligand ICAM-1 mediates not only cell adhesion but also signal transduction in immunologic and inflammatory cell responses. Basal ICAM-1 expression is normally low on nonhematopoietic cells, but it can be subject to an up-and-down regulation by various cytokines. ICAM-1 expression was found in 8/9 PVR membranes, in 9/10 PDR membranes, in 4/4 macular pucker, and in 7/8 recurrent membranes after intraocular silicone oil tamponade. Coexpression of LFA-1 was detected in all but one of the ICAM-1 -positive membranes. The high frequency of ICAM-1/LFA-1 coexpression in epiretinal membranes indicates an important role in the pathogenesis of epiretinal membrane formation.