Diclofenac hypersensitivity: antibody responses to the parent drug and relevant metabolites.
BACKGROUND
Hypersensitivity reactions against nonsteroidal antiinflammatory drugs (NSAIDs) like diclofenac (DF) can manifest as Type I-like allergic reactions including systemic anaphylaxis. However, except for isolated case studies experimental evidence for an IgE-mediated pathomechanism of DF hypersensitivity is lacking. In this study we aimed to investigate the possible involvement of drug- and/or metabolite-specific antibodies in selective DF hypersensitivity.


RESULTS
DF, an organochemically synthesized linkage variant, and five major Phase I metabolites were covalently coupled to carrier proteins. Drug conjugates were analyzed for coupling degree and capacity to crosslink receptor-bound IgE antibodies from drug-sensitized mice. With these conjugates, the presence of hapten-specific IgE antibodies was investigated in patients' samples by ELISA, mediator release assay, and basophil activation test. Production of sulfidoleukotrienes by drug conjugates was determined in PBMCs from DF-hypersensitive patients. All conjugates were shown to carry more than two haptens per carrier molecule. Immunization of mice with drug conjugates induced drug-specific IgE antibodies capable of triggering mediator release. Therefore, the conjugates are suitable tools for detection of drug-specific antibodies and for determination of their anaphylactic activity. Fifty-nine patients were enrolled and categorized as hypersensitive either selectively to DF or to multiple NSAIDs. In none of the patients' samples evidence for drug/metabolite-specific IgE in serum or bound to allergic effector cells was found. In contrast, a small group of patients (8/59, 14%) displayed drug/metabolite-specific IgG.


CONCLUSIONS
We found no evidence for an IgE-mediated effector mechanism based on haptenation of protein carriers in DF-hypersensitive patients. Furthermore, a potential involvement of the most relevant metabolites in DF hypersensitivity reactions could be excluded.
Division of Allergy and Immunology, Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
Andrea
A
Harrer
Roland
R
Lang
Robert
R
Grims
Michaela
M
Braitsch
Thomas
T
Hawranek
Werner
W
Aberer
Lothar
L
Vogel
Walther
W
Schmid
Fatima
F
Ferreira
Martin
M
Himly
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000009:adverse effects*; D000906:Antibodies / Q000276:immunology*; D001491:Basophils / Q000276:immunology; D004008:Diclofenac / Q000009:adverse effects*; D004342:Drug Hypersensitivity / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000906:Antibodies; D004008:Diclofenac; D007073:Immunoglobulin E