title: Serum 25-hydroxyvitamin D and IgE - a significant but nonlinear relationship.
abstract: BACKGROUND
  Hormonal vitamin D system affects the determination of T-cell responses. It is unknown if there is an association between vitamin D status and allergic conditions. Our aim was to investigate differences in serum IgE concentrations by vitamin D status [measured by 25(OH)D] and by a genetic variation in a key vitamin D activation enzyme (CYP27B1) previously shown to be associated with type 1 diabetes.
  
  
  METHODS
  9377 participants in the 1958 British birth cohort completed a biomedical assessment at 45 years of age ; 7288 eligible participants had data on 25(OH)D and IgE, with 6429 having further information on CYP27B1 genotype ()1260C>A).
  
  
  RESULTS
  There was a nonlinear association between 25(OH)D and IgE (P-value for curvature = 0.0001). Compared with the reference group with the lowest IgE concentrations [25(OH)D 100-125 nmol/l], IgE concentrations were 29% higher (95% CI 9-48%) for participants with the 25(OH)D <25 nmol/l, and 56% higher (95% CI 17-95%) for participants with 25(OH)D >135 nmol/l (adjusted for sex, month, smoking, alcohol consumption, time spent outside, geographical location, social class, PC/TV time, physical activity, body mass index and waist circumference). CYP27B1 genotype was associated with both 25(OH)D (difference for A vs. C allele: 1.88%, 95% CI 0.37-3.4%, P = 0.01) and IgE concentrations ()6.59%, )11.6% to )1.42%, P = 0.01).
  
  
  CONCLUSIONS
  These data suggest that there may be a threshold effect with both low and high 25(OH)D levels associated with elevated IgE concentrations. The same CYP27B1 allele that is protective of diabetes was associated with increased IgE concentrations.
authors.affiliation: MRC Centre for the Epidemiology of Child Health, UCL Institute of Child Health, London, UK.
authors.forename: E
authors.initials: E
authors.lastname: Hyppönen
authors.forename: D J
authors.initials: DJ
authors.lastname: Berry
authors.forename: M
authors.initials: M
authors.lastname: Wjst
authors.forename: C
authors.initials: C
authors.lastname: Power
mesh_terms: D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005838:Genotype; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D008297:Male; D008875:Middle Aged; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; D007073:Immunoglobulin E; C104450:25-hydroxyvitamin D; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase