The
enzyme activity of
arylsulfatase A and
arylsulfatase B was studied in Epstein-Barr virus-transformed lymphoid cell lines established from control individuals and patients affected with
metachromatic leukodystrophy,
mucopolysaccharidosis type VI (or
Maroteaux-Lamy syndrome) and
multiple sulfatase deficiency. Lymphoid cells derived from patients with
metachromatic leukodystrophy showed a severe deficiency in
cerebroside sulfatase activity, as measured using radiolabelled
sulfatide, but some residual activity of
arylsulfatase A when measured with the
chromogenic substrate,
para-nitrocatechol sulfate. Lymphoid cells from
mucopolysaccharidosis type VI had virtually no
arylsulfatase B activity. In cells from patients with
multiple sulfatase deficiency, the activities of lysosomal
sulfatases as well as
steroid sulfatase were deficient. Study of the molecular forms of
arylsulfatases confirmed the complete deficiency of
arylsulfatase A and
arylsulfatase B activities in
metachromatic leukodystrophy and
mucopolysaccharidosis type VI lymphoid cells, respectively. The
arylsulfatase A defect in metachromatic leukodys-lymphoid cells, respectively. The
arylsulfatase A defect in
metachromatic leukodystrophy cells could be demonstrated on focused fractions even using the artificial substrates,
para-nitrocatechol sulfate and
4-methylumbelliferyl sulfate. To investigate the discrepancy of the
arylsulfatase A activity data observed between whole cell homogenates and focused fractions when using the synthetic substrates, assays were tentatively performed for optimizing the determination of
arylsulfatase A on crude homogenates of lymphoid cells. Although this work has indicated methodological limitations of the enzymatic assay of
arylsulfatase A in lymphoid cells using methylumbelliferyl
sulfate, it emphasizes the validity of lymphoid cell lines as an experimental model for the study of inborn deficiencies of
arylsulfatases A and B.