Lymphocytes in mucopolysaccharidosis type VI patients

Mucopolysaccharidoses are lysosomal storage diseases (LSD) characterized by the accumulation of glycosaminoglycans. The focus of this work is Mucopolysaccharidosis type VI (MPS VI), which is a disorder caused by mutations in the gene encoding the ASB enzyme (ARSB). In this disease there is accumulation of the glycosaminoglycan dermatan sulfate. The lysosome is an important organelle in the presentation of lipid antigen to T cells. Invariant natural killer T cells (iNKT) are the most studied lipid specific T cells and are well known by their immunoregulatory properties. We analyze the lymphocyte populations of 11 MPS VI patients and 11 control subjects by flow cytometry. All the patients analyzed were under Enzyme Replacement Therapy with Naglazyme. We found an increase percentage of B-lymphocytes in MPS VI patients when compared with control subjects. No alterations were found in the percentage of the T and iNKT cells and in their subsets according to CD4 and CD8 expression in MPS VI patients. These parameters have been previously analyzed for other LSDs in our laboratory and imbalances in the iNKT cell subsets were found namely in Fabry and Gaucher disease patients (see abstract by Cátia Pereira et al). Therefore the results obtained with the Mucopolysaccharidoses patients highlight the fact that lysosome dysfunction per se is not sufficient to induce iNKT subset alterations. The alterations found in the B lymphocyte population of the MPS VI patients should be further explored.