The nature of mannose-containing material which accumulates in cultured fibroblasts from patients with mannosidosis.

Fibroblasts from a patient with mannosidosis were grown in a medium containing a radioactive monosaccharide (D-[U-14C]mannose or N-acetyl-D-[1-14C]-glucosamine). An accumulation of radioactive material was observed. It was possible to prevent the accumulation to a certain degree by the addition of human liver alpha-D-mannosidase to the fibroblast medium. After six days of fibroblast culture the majority of the accumulated material had a molecular weight in the oligosaccharide range and was stationary during high-voltage electrophoresis. Paper chromatography of the stationary material separated three radioactive compounds with the same chromatographic mobilities as the oligosaccharides alpha-D-Man-(1 leads to 3)-beta-D-Man-(1 leads to 4)-D-GlcNAc (I), alpha-D-Man-(1 leads to 2)-alpha-D-Man-(1 leads to 3)-beta-D-Man-(1 leads to 4)-GlcNAc (II), and alpha-D-Man-(1 leads to 2)-alpha-D-Man-(1 leads to 2)-alpha-D-Man-(1 leads to 3)-beta-D-Man-(1 leads to 4)-GlcNAc (III) previously isolated from the urine of patients with mannosidosis. Degradation of the three radioactive compounds with jack bean alpha-mannosidase gave D-mannose and a disaccharide (containing D-mannose and N-acetyl-D-glucosamine). Thus the three main compounts observed in the fibroblasts from patients with mannosidosis are most probably identical to the oligosaccharides I--III.