PROLIFERATIVE VITREORETINOPATHY - AN EXAMINATION OF THE INVOLVEMENT OF LYMPHOCYTES, ADHESION MOLECULES AND HLA-DR ANTIGENS

This paper addresses the molecular basis of interactions between leuco cytes, other cells in the vitreoretinal environment and extracellular matrix that may underlie the pathogenesis of proliferative vitreoretin opathy. In this study we report the expression of adhesion molecules ( CD11a, CD11c, CD18 and ICAM-1), lymphocyte surface markers (CD3, CD4, CD8 and CD22) and HLA-DR molecules in 25 epiretinal membranes obtained from eyes undergoing vitrectomy for the treatment of retinal detachme nt complicated by epiretinal membrane formation. Retinas from normal c adaveric eyes were used as controls. The results showed that cells exp ressing the adhesion molecules CD11a, CD11c and CD18 were present in 5 of 25, 17 of 25 and 11 of 23 membranes, respectively. Cells stained w ith antibodies against intracellular adhesion molecule 1 (ICAM-1) were observed in 24 of 25 membranes, whilst HLA-DR positive cells were see n in all membranes investigated. Immunohistochemical staining revealed that the molecules ICAM-1 or HLA-DR were not only expressed on inflam matory cells but also distributed within the extracellular matrix in s everal specimens. Lymphocytes expressing CD3 markers were present in 1 2 of 25 membranes, whilst T lymphocytes expressing CD4 and CD8 markers were observed in 5 of 18 and 12 of 24 membranes, respectively. In con trast, B lymphocytes expressing CD22 molecules were not found in any o f the membranes. Leucocyte surface molecules were not expressed in con trol cadaveric retinas, although occasional cells expressing ICAM-1 we re identified in the inner plexiform layer. The present findings indic ate that selective interaction between infiltrating leucocytes and adh esion molecules present in extracellular matrix may well be involved i n epiretinal membrane formation, and that T lymphocytes may play an im portant role in the pathogenesis of proliferative vitreoretinopathy.