COLLAGEN TYPE-I AND TYPE-III IN GIANT PAPILLAE OF VERNAL KERATOCONJUNCTIVITIS

Aims-The objective of this study was to investigate alterations in con junctival collagen and proteoglycans in the conjunctival giant papilla e of patients with vernal keratoconjunctivitis (VKC). Methods-Tissue s amples from tarsal giant papillae of seven eyes from five patients wit h VKC, and five tarsal conjunctival samples from five normal patients were obtained. Tissues were processed and stained with haematoxylin an d eosin, Van Gieson, trichromic Mallory, toluidine blue, Alcian blue, and alkaline Giemsa. Collagen extraction was performed in acetic acid and pepsin, total collagen was quantified using hydroxyproline levels, and collagen types I and III were analysed by gel electrophoresis (SD S-PAGE). Proteoglycans were quantified using uronic acid levels. Resul ts-Histological evaluation showed a significant increase of mast cells in the epithelium (0/mm(2) v 147/mm(2), p<0.01) and in the stroma (5. 1/mm(2) v 80/mm(2), p<0.01) of VKC patients. Collagen fibres were thic ker and arranged irregularly, with the total amount significantly incr eased. Owing to an increased percentage of type III collagen, the rati o of collagen types I to III was decreased. Proteoglycans were also re duced in VKC samples. Conclusion-The well known morphological abnormal ities observed in VKC correspond to alterations in the ratio between c ollagens and proteoglycans, and between different types of collagen. T he greatly increased number of mast cells found in these tissues sugge sts an active role for these cells in the abnormal connective tissue m etabolism observed in VKC.