title: Combined in vivo and in vitro approach for the characterization of penicillin-specific polyclonal lymphocyte reactivity: tolerance tests with safe penicillins instead of challenge with culprit drugs.
abstract: BACKGROUND
  Amino-penicillins are a major cause of delayed-type reactions to penicillins.
  
  
  OBJECTIVE
  The aim of this study was to establish a diagnostic approach for the characterization of the individual penicillin-specific polyclonal lymphocyte reactivity in order to detect side chain-specific sensitization to amino-penicillins. Patients can then be advised to undergo a tolerance test with safe penicillins instead of provocation with culprit penicillins for confirmation of penicillin allergy.
  
  
  METHODS
  We investigated penicillin-specific polyclonal lymphocyte reactivity in nine patients with delayed-type reactions to amino-penicillins by a combined in vivo (patch, prick and intracutaneous tests with delayed readings) and in vitro (lymphocyte transformation test, LTT) approach.
  
  
  RESULTS
  A combination of LTT and skin tests improved the sensitivity for the characterization of penicillin-specific polyclonal lymphocyte reactivity and allowed the detection of three different patterns of lymphocyte reactivity. Four patients showed a side chain-specific sensitization to amino-penicillins in vivo and in vitro and were advised to undergo tolerance tests with safe penicillins. Two patients agreed and were exposed to parenteral benzyl-penicillin and oral phenoxymethyl-penicillin which they tolerated without complications.
  
  
  CONCLUSIONS
  These data suggest that a combined in vivo and in vitro approach is helpful for the detection of side chain-specific sensitization to amino-penicillins. Patients with such sensitization are very likely to tolerate safe penicillins, thereby expanding their therapeutic options when antibiotic treatment is required.
authors.affiliation: Department of Dermatology and Allergology, Rheinisch-Westfälische Technische Hochschule Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany. bcsachs@tiscalinet.de
authors.forename: B
authors.initials: B
authors.lastname: Sachs
authors.forename: T
authors.initials: T
authors.lastname: Al Masaoudi
authors.forename: H F
authors.initials: HF
authors.lastname: Merk
authors.forename: S
authors.initials: S
authors.lastname: Erdmann
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D002478:Cells, Cultured; D002511:Cephalosporins / Q000494:pharmacology; D003429:Cross Reactions; D003875:Drug Eruptions / Q000175:diagnosis* / Q000209:etiology; D004361:Drug Tolerance; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D010400:Penicillin G / Q000009:adverse effects; D010406:Penicillins / Q000009:adverse effects* / Q000494:pharmacology; D012882:Skin Tests / Q000379:methods; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000187:drug effects*
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D000667:Ampicillin; D010400:Penicillin G