INTRACELLULAR TRANSPORT OF GLYCOSAMINOGLYCANS (MUCOPOLYSACCHARIDES) IN HUMAN LEUKOCYTES

The subcellular progression in myeloid cells of newly synthesized chondroitin sulfate was studied in vitro by pulse labeling with 35S-sulfate and 14C-glucosamine. Leukocytes from the peripheral blood of healthy individuals exhibited a decreasing 35S specific activity of the subcellular fractions after the pulse indicating polysaccharide degradation or secretion. In myeloid leukemic cells the specific activities of both 35S-sulfate and 14C-hexosamine labeled material of the microsomal fraction displayed a decrease after the initial rise while the specific activity of the granule fraction increased steadily with time. The results indicate that the chondroitin sulfate which has been newly synthesized on microsomal structures is transferred to the granule fraction. The different behaviour between the non leukemic (mature myeloid cells) and the leukemic cell population (predominantly immature myeloid cells) may indicate that the chondroitin sulfate stored in the granules is synthesised during cell maturation possibly in the process of manufacturing specific granules. The solubility of the cetylpyridinium complexes and the electrophoretic mobility of the chondroitin sulfate obtained from the granule and the microsomal fraction suggest a continuous breakdown in the granules of stored polysaccharide. © 1969.