Immunologic evaluation of immediate hypersensitivity to cefaclor

Abstract

PURPOSE: Cefaclor is widely prescribed for various infectious diseases. As its

consumption increases, the number of hypersensitivity reactions to cefaclor has

increased. This study aimed to evaluate the immunologic findings of immediate

hypersensitivity to cefaclor. MATERIALS AND METHODS: We enrolled 47 patients with

immediate hypersensitivity to cefaclor from Ajou University Hospital and Asan

Medical Center. Serum specific IgE, IgG1, and IgG4 antibodies to cefaclor-human

serum albumin (HSA) conjugate were measured by enzyme-linked immunosorbent assay

(ELISA). RESULTS: The most common phenotype was anaphylaxis (Group I, 78.7%),

followed by urticaria (Group II, 21.3%). The detection of specific IgE, IgG1, and

IgG4 to cefaclor-HSA conjugate by ELISA tended to be higher in Group I (40.5%,

41.7%, 21.6%) than in Group II (20.0%, 20.0%, 0%) with no statistical

significance. Significant associations were found between specific IgE and IgG1

or IgG4 (p<0.001, p=0.019). ELISA inhibition tests showed significant inhibitions

by both free cefaclor and cefaclor-HSA conjugate. For basophil activation tests

in patients having no specific IgE antibody, the CD63 expression level on

basophils increased with incubations of free cefaclor. CONCLUSION: The most

common manifestation of immediate hypersensitivity to cefaclor was anaphylaxis,

most of which was mediated by IgE; however, a non-IgE mediated direct basophil

activation mechanism was suggested in a subset of anaphylaxis patients.