title: IgE antibodies to betalactams: relationship between the triggering hapten and the specificity of the immune response.
abstract: BACKGROUND
  In immunoglobulin (Ig)E-mediated responses to betalactams (BL) the antibody is directed to the hapten inducing the response. For benzylpenicillin (BP) the determinant is benzylpenicilloyl (BPO) and for amoxicillin (AX), amoxicilloyl (AXO). Because of cross-reactivity, IgE from some patients reacts to both drugs whereas others have a drug-selective recognition. After an allergic episode, there is an increase in IgE that decreases over time. We analysed the response of patients allergic to BL after penicillin administration, with emphasis on IgE cross-reactivity.
  
  
  METHODS
  Subjects who developed an IgE antibody response were studied. Sequential follow-up samples were obtained at different times during the response. Changes in IgE specificity were analysed by competition immunoassays using different penicillin monomeric conjugates.
  
  
  RESULTS
  Two patterns of response were existed: one with IgE directed to the culprit penicillin and another with IgE mainly reactive to BPO. In both, a variable cross-reactivity with the hapten triggering the boosting response was found. This pattern was maintained with no change in specificity over time, even in subjects who experienced one boosting event.
  
  
  CONCLUSIONS
  The IgE response can be specific to the drug inducing the reaction or cross-reactive to the classical BPO determinant. This pattern is maintained throughout the whole period of the response, even if re-exposure occurs. The stability of the type of response can be explained by the phenomenon of original antigenic sin: in the presence of antibodies, memory B cells are more easily triggered than naive B cells.
authors.affiliation: Research Laboratory, Carlos Haya Hospital, Málaga, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Antúnez
authors.forename: T
authors.initials: T
authors.lastname: Fernández
authors.forename: N
authors.initials: N
authors.lastname: Blanca-Lopez
authors.forename: M J
authors.initials: MJ
authors.lastname: Torres
authors.forename: C
authors.initials: C
authors.lastname: Mayorga
authors.forename: G
authors.initials: G
authors.lastname: Canto
authors.forename: J
authors.initials: J
authors.lastname: Fernández
authors.forename: M C
authors.initials: MC
authors.lastname: Moya
authors.forename: M
authors.initials: M
authors.lastname: Blanca
mesh_terms: D000918:Antibody Specificity / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology; D003429:Cross Reactions / Q000276:immunology; D004342:Drug Hypersensitivity / Q000097:blood / Q000276:immunology*; D005260:Female; D006241:Haptens / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D007156:Immunologic Memory / Q000276:immunology; D008297:Male; D013997:Time Factors; D047090:beta-Lactams / Q000009:adverse effects / Q000276:immunology*
chemical_list: D006241:Haptens; D047090:beta-Lactams; D007073:Immunoglobulin E