Vitamin D deficiency and insufficiency are prevalent in Hong Kong Chinese children. Vitamin D deficiency is associated with childhood AD and high total IgE. Serum 25(OH)D levels correlate inversely with both long- and short-term AD severity.

Summary. Platelet-derived growth factor (PDGF) is a major mitogen for connective tissue cells. In this study, we investigated the effects and mechanism of PDGF on the ex vivo expansion of cord blood CD34 + cells. Our data demonstrated that among various cytokine combinations of thrombopoietin (TPO), interleukin 1 beta (IL-1b), IL-3, IL-6 and Flt-3 ligand (Flt-3L), TPO + IL-6 + Flt-3L was most efficient in promoting the expansion of CD34 + cells, CD34 + CD38 -cells, mixed-lineage colony-forming units (CFU-GEMM) and long-term culture-initiating cells (LTC-IC) by 21AE7 ± 5AE00-, 103 ± 27AE9-, 10AE7 ± 7AE94-and 6AE52 ± 1AE51-fold, respectively, after 12-14 d of culture. The addition of PDGF increased the yield of these early progenitors by 45AE0%, 66AE5%, 45AE1% and 79AE8% respectively. More significantly, PDGF enhanced the engraftment of human CD45 + cells and their myeloid subsets (CD33 + , CD14 + cells) in non-obese diabetic (NOD)/severe-combined immunodeficient (SCID) mice. The expression of PDGF receptor (PDGFR)-b was not detectable in fresh CD34 + cells but was upregulated after culture for 3 d. PDGF also enhanced the development of adherent cells/clusters that expressed the endothelial markers VE-cadherin and CD31. These findings suggest that PDGF is an effective cytokine for the ex vivo expansion of early stem and progenitor cells. The mechanism could be mediated by PDGFR-b on committed CD34 + progenitor cells and/or secondary to the stimulation of autologous, stromal feeder cells.

Maroteaux-Lamy syndrome, or mucopolysaccharidosis type VI (MPS VI), is an autosomal recessive inborn metabolic disorder due to deficiency of the enzyme N-acetylgalactosamine-4-sulphatase, resulting in accumulation of glycosaminoglycans in most tissues. Affected individuals have coarse skin and facial features, dysostosis multiplex, hepatosplenomegaly, corneal cloudiness, upper airway nar-