Lectin-binding in normal and fibrillated articular cartilage of human patellae

Fluorescein-isothiocyanate (FITC) labeled lectins were used to study the distribution of specific binding-sites in histological sections of normal and fibrillated articular cartilage of human patellae. It has been shown that normal articular cartilage reveals lectin binding-sites for Concanavalin A (Con A) and wheat germ agglutinin (WGA), but not for soybean agglutinin (SBA), peanut agglutinin (PNA) and Ulex europaeus agglutinin (UEA). In fibrillated cartilage the distribution pattern of Con A and WGA is completely changed. SBA, PNA and UEA show a distinct staining pattern in particular in the fibrillated areas of degenerated cartilage. Lectin-staining of the extracellular matrix and the chondrocytes in both normal and fibrillated cartilage did not show any correlation with material that was either PAS- or Alcian blue-positive. In comparison with the conventional PAS- and Alcian blue reaction lectin-staining proved to be superior. Visualization of intra- and extracellular glycoconjugate-changes in normal and fibrillated cartilage in areas with no PAS and/or Alcian blue staining indicates that all layers of the cartilage are involved in the pathological process. It is evident that lectins can demonstrate minute differences between normal and arthrotic cartilage and we therefore conclude that lectins are sensitive and specific tools for the study of degenerative joint diseases.