Newborn screening for hunter disease: a small-scale feasibility study.

Hunter disease (Mucopolysaccharidosis type II, MPS II) is an X-linked lysosomal storage disorder caused by deficiency of iduronate-2-sulfatase (IDS). Two main therapies have been reported for MPS II patients: enzyme-replacement therapy (ERT) and hematopoietic stem-cell transplantation (HSCT). Both treatment modalities have been shown to improve some symptoms, but the results with regard to cognitive functioning have been poor. Early initiation of therapy, i.e., before neurological symptoms have manifested, may alter cognitive outcome. The need for early identification makes Hunter disease a candidate for newborn screening (NBS). Our objective was to explore the use of a fluorometric assay that could be applicable for high-throughput analysis of IDS activity in dried blood spots (DBS). The median IDS activity in DBS samples from 1,426 newborns was 377 pmol/punch/17 h (range 78-1111). The IDS activity in one sample was repeatedly under the cutoff value (set at 20% of the median value), which would imply a recall rate of 0.07%. A sample from a clinically diagnosed MPS II individual, included in each 96-well test plate, had IDS activities well below the 20% cutoff value. Coefficients of variation in quality control samples with low, medium, and high IDS activities (190, 304, and 430 pmol/punch/17 h, respectively) were 12% to 16%. This small-scale pilot study shows that newborn screening for Hunter disease using a fluorometric assay in DBS is technically feasible with a fairly low recall rate. NBS may allow for identification of infants with Hunter disease before clinical symptoms become evident enabling early intervention.

Variable leukocyte composition of red blood cell concentrates prepared in top-bottom systems: possible implications for pre-transplant blood transfusion.

BACKGROUND AND OBJECTIVES: The beneficial effect of blood transfusion on kidney graft survival requires the presence of leukocytes in the transfusate, but a minimal dose has not been defined, nor has the role of individual leukocyte subsets been investigated. In the Netherlands, a standard pre-transplant blood transfusion consists of a buffy coat (BC)-depleted red blood cell concentrate (RBCC) containing a maximum of 1.2x10(9) residual leukocytes per unit. However, leukocyte subset composition is not standardized. MATERIALS AND METHODS: Using FACS analysis, this study compared the residual leukocyte composition of RBCCs produced by Compomat((R)) and Optipress((R)), two currently used top-bottom systems. RESULTS: While the total leukocyte content of the RBCCs was equivalent in both press types (0.5x10(9)), the percentage of mononuclear cells (lymphocytes and monocytes) was significantly higher in the Compomat as compared with the Optipress system (p < 0. 0001), resulting in significantly higher numbers of transfused T cells, B cells, HLA-DR-positive cells, NK cells and stem cells. CONCLUSIONS: The leukocyte composition of a pre-transplant blood transfusion depends on the BC depletion method used; this might differentially affect the tolerizing or immunizing potential of a pre-transplant blood transfusion.

Characterization of a human plasmacytoma line.

The TH line was established by bringing tumour cells from a multiple myeloma patient into suspension culture and subsequently cloning them by limiting dilution. The cultured cells show marked heterogeneity; there are ultrastructural differences between small and large TH cells, particularly with respect to the rough endoplasmatic reticulum (RER). Karyotyping revealed chromosome numbers in the triploid range, with many structural abnormalities, at the 14q32 region among others. A t(14;18) could not be demonstrated. TH was shown to have germline and a rearranged allele for kappa light chain, and only a single rearranged gene for heavy chain immunoglobulin. TH expressed PCA-1, CD9, CD28 and CD38 antigens, HLA class II, RER and kappa light chain, but few or no other antigens associated with the B-cell lineage. Light chain kappa and trace amounts of IgG3 were found intracellularly as well as in culture supernatant. The addition of IL-6 to cultures of TH increased proliferation, as well as the secretion of kappa light chain and the membrane expression of CD28 and CD38 antigens. Because TH has relatively few B cell markers on its membrane, it may be useful for the induction of monoclonal antibodies specific for human plasma cells. It also provides a model for the demonstration that IL-6 can act as a paracrine growth and differentiation factor for cells of myelomal origin.