Cytochemical analysis of storage materials in cultured skin fibroblasts from patients with I-cell disease

BackgroundIn cultured fibroblasts from I-cell disease patients the transport of many lysosomal enzymes is defective, and affected cells contain inclusion bodies filled with undegraded substrates. However, the contents of these inclusion bodies have not been well characterized yet. We attempted to identify accumulated substances in cultured I-cell disease fibroblasts cytochemically.MethodsCultured fibroblasts from I-cell disease patients were double-stained with a monoclonal antibody to lysosome-associated membrane protein-1 (LAMP-1) and that to GM2 ganglioside, or a series of lectins that specifically bind to sugar moieties.ResultsThe patients' cells were granularly stained with the antibody to GM2 ganglioside and the lectins including Maakia amurensis, Datura stramonium, and concanavalin A. Their localization was coincident with that of LAMP-1.ConclusionsGM2 ganglioside and various kinds of glycoconjugates having sialic acidα2-3galactose, galactoseβ1-4N-acetylglucosamine and mannose residues accumulate in enlarged lysosomes in I-cell disease fibroblasts.