Abstract
Normal levels of acidic α-man activity have been found in the culture medium of a number of mannosidosis fibroblast lines. This observation is different from most other lysosomal storage diseases in which enzyme deficiency is evident both intra- and extracellularly. Studies were undertaken in order to determine if the extracellular α-man is in fact a product of the cells. Cells cultivated in medium containing fetal calf serum from which acidic α-man was removed by concanavalin A adsorption excreted normal amounts of α-man. The extracellular enzyme exhibited normal thermostability and normal kinetics. Incubation of mannosidosis extracellular enzyme with either normal or patient cell lysate resulted in a partial loss of acidic α-man activity whereas an additive value was observed when the normal extracellular enzyme was incubated with cell lysate of either type. Addition of medium from normal cell cultures to mucolipidosis II fibroblasts previously cultured in presence of [3H] mannose resulted in reduction of the intracellular storage of mannose-containing macromolecules. In contrast, no correction could be demonstrated with medium from mannosidosis cell cultures. These findings suggest that the mutation in mannosidosis results in altered catalytic properties and thermostability only after complete intracellular processing. The final processing presumably takes place within the lysosomes and the extracellular enzyme which has escaped this step therefore does not express the defect.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ben-Yoseph, Y., Hahn, L., Defranco, C. et al. 777 MANNOSIDOSIS: CATALYTICALLY ACTIVE EXTRACELLULAR ACIDIC α-MANNOSIDASE (α-man) DUE TO INCOMPLETE PROCESSING. Pediatr Res 15 (Suppl 4), 572 (1981). https://doi.org/10.1203/00006450-198104001-00801
Issue Date:
DOI: https://doi.org/10.1203/00006450-198104001-00801