RESUMEN
To evaluate the role of immunological mechanisms in the etiology off primary pterygia, 20 cases of surgically excised primary pterygium presenting at various clinical stages were examined with morphological and immunohistochemical methods, and compared with normal conjunctiva excised from the nasal part of the limubs. B5-fixed, paraffin-embedded tissue was stained with anti-bodies directed against T-cells, B-cells, macrophages, Langerhans cells, HLA-DR antigens and immunoglobulins. Increased numbers of dendritic cells variably expressing s-100 protein, HLA-DR antigens and/or the LN2-marker, were observed both in the epithelium and underlying stroma. In addition, the elastotically degenerated stroma contained variable numbers off KP1 + macrophages. T- and B- lymphocytes as well as immunoglobulin-containing plasma cells were generally inconspicuous