Lectin binding patterns of the human cornea. Comparison of frozen and paraffin sections

Twelve FITC-conjugated lectins were used to establish a reaction pattern with cellular and noncellular components in fresh-frozen and formalin-fixed paraffin sections of 11 normal human corneas. In frozen sections the epithelium demonstrated the most active lectin staining; keratocytes and endothelium stained to a lesser degree. Of the noncellular components, the epithelial basement membrane and Descemet's membrane of some of the tissues were stained most by Phasolus vulgaris agglutinin (PHA), Pisum sativum agglutinin (PSA), Concanavalin A (Con-A), and Sopora japonica agglutinin (SJA). None of the lectins stained Bowman's layer or the stromal matrix. Keratocytes in paraffin sections stained the most compared with the epithelium and endothelium. In paraffin sections, the epithelial basement membrane and Bowman's layer of some of the tissue sections were stained by Con-A, Ricinus cummuni agglutinin 120 (RCA-120), Banderiraea simplicifolia lectin (BSL-I), PHA, and wheat germ agglutinin (WGA). From this study, it was observed that the reactivity of lectins to the cellular components in paraffin-embedded sections was less pronounced than in frozen sections. Sensitivity of lectin binding was considerably enhanced by the proteolytic enzyme digestion of paraffin sections.