title: Elevated serum total IgE alter the diagnostic performance of radio-immune assays for β-lactam specific antibody dosing.
abstract: BACKGROUND
  In vivo allergy tests and the detection of drug-specific antibodies are widely used in the diagnosis of β-lactam induced immediate-type hypersensitivity reactions. The diagnostic performance of immunoenzymatic tests for the demonstration of serum-specific IgE (IgEs) antibodies is influenced by total IgE values (IgEt). The aim of this study was to investigate whether the result obtained by radioimmunoassays (RIA) for β-lactams IgEs antibodies is correlated to IgEt.
  
  
  METHODS
  68 paired in vivo and in vitro tests were performed for the culprit drugs in 49 patients with suspected previous hypersensitivity reactions to β-lactams. 14 controls who tolerated the tested antibiotics were similarly investigated. The dosing of IgEt was performed using the Immulite Immunoassay (Siemens). We detected IgEs using a sandwich-type RIA with sepharose as solid phase (Pathologie Cellulaire et Moléculaire en Nutrition, France) and anti-IgEs I(125)-labelled antibodies (Immunotech, Czech Republic).
  
  
  RESULTS
  RIA-IgEs sensitivity was 56.52% in patients with IgEt < 120 IU/mL and 90.90% in patients with IgEt > 120 IU/mL (p = 0.0052). All patients with IgEt > 500 IU/mL had positive RIA results. RIA-IgEs specificity was 90.90% for IgEt < 120 IU/mL and 66.66% for IgEt > 120 IU/mL. The linear equation that fits the relation between IgEt and IgEs is: IgEs = (IgEt + 81.644)/137.94, with a correlation coefficient of 0.4.
  
  
  CONCLUSIONS
  Serum total IgE alter the diagnostic performance of radioimmunoassays for β-lactam specific antibody dosing. Assays for the detection of both IgEt and IgEs need to be performed for each individual investigated, retrospectively, to confirm clinical immediate-type hypersensitivity reactions.
authors: Cristina
authors: C
authors: Petrişor
authors: Manuela
authors: M
authors: Sfichi
authors: Nadia
authors: N
authors: Gherman
authors: Ramona
authors: R
authors: Bologa
authors: Natalia
authors: N
authors: Hagău
mesh_terms: D016022:Case-Control Studies; D004342:Drug Hypersensitivity / Q000097:blood / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood*; D010641:Phenotype; D011863:Radioimmunoassay; D012882:Skin Tests; D047090:beta-Lactams / Q000009:adverse effects* / Q000276:immunology*
chemical_list: D047090:beta-Lactams; D007073:Immunoglobulin E