Cytological and immunohistochemical study of the limbal form of vernal keratoconjunctivitis by the replica technique.

The cellular composition of the inflammatory infiltrate present in 13 patients with the limbal form of vernal keratoconjunctivitis was examined in the conjunctival scrapings and the limbic replicas by means of Giemsa stain and immunohistochemistry. Conjunctival scrapings showed the presence of mast cells, lymphocytes, plasma cells, polymorphonuclear leucocytes, and very few basophils in all the specimens. Eosinophils were present in only four scrapings. The superficial epithelium of the limbic lesion and the adjacent cornea and conjunctiva was studied by the replica technique. The limbic lesion area showed the presence of necrotic epithelial cells mixed with inflammatory cells, including eosinophils, mast cells, lymphocytes, plasma cells, and polymorphonuclear leucocytes and very few basophils. Most of the inflammatory cells were HLA-DR+. Many OKT6+ cells were present, indicating the presence of Langerhans cells. T-lymphocytes including a few helper/inducer cells and many suppressor/cytotoxic cells, were detected in the infiltrate. In addition many B-lymphocytes were observed. These findings suggest that other immune mechanisms in addition to type 1 reaction are involved in the pathogenesis of the disease.