Cholesterol sulfate is not degraded but does not accumulate in Epstein-Barr virus-transformed lymphoid cells from patients with X-linked ichthyosis

Abstract

The metabolism of cholesterol sulfate (CS) was investigated in immortalized, Epstein-Barr virus-transformed lymphoid cell lines derived from normal individuals and patients affected with recessive X-linked ichthyosis (XLI). Normal lymphoid cells expressed arylsulfatase C and steroid sulfatase (including cholesterol sulfatase) activities, and these two sulfohydrolases showed the same enzyme properties as in other human cells, e.g., leukocytes or skin fibroblasts. XLI-derived lymphoid cell lines exhibited extremely deficient activity of both arylsulfatase C and steroid sulfatase. While normal and XLI intact, living lymphoid cells could take up exogenous radiolabelled CS through a non-receptor-mediated process, XLI cells were completely unable to degrade CS to cholesterol. However, despite their defect in CS degradation, steroid sulfatase-deficient cells did not accumulate CS because of outflux of this sterol. The potential implications of these findings to the pathogenesis of increased CS content in plasma and epidermis of XLI patients are discussed. This study also demonstrates that immortalized lymphoid cell lines may represent a useful experimental model system for the study of XLI.