Required cefazolin concentration to maximize diagnostic accuracy of the basophil activation test for cefazolin-induced anaphylaxis

Tatsuo Horiuchi, Tomonori Takazawa, Masaki Orihara, Shinya Sakamoto, Akihiko Yokohama, Junko Takahashi, Akihiro Tomioka, Nagahide Yoshida, Kazuaki Hagiwara, Shigeru Saito

Identifying the causative agent of perioperative anaphylaxis is key to preventing its recurrence. Besides skin testing, the basophil activation test (BAT) is increasingly being accepted as an additional and reliable method. Cefazolin seems to be a major cause of perioperative anaphylaxis. However, few studies have described use of the BAT for cefazolin-induced anaphylaxis. In this study, we aimed to determine the optimum cefazolin concentration required in the BAT for an accurate diagnosis. Seven patients who presented with immediate hypersensitivity to cefazolin and 21 control subjects were studied. We conducted skin tests and performed BATs using both CD203c and CD63 as markers of activated basophils. We measured the ratio of activated basophils after stimulation with serial dilutions of cefazolin and investigated the cefazolin concentration that resulted in better sensitivity and specificity. All patients demonstrated positive reactions to cefazolin, while all control subjects showed negative reactions on skin tests. The net percentage of both CD203c- and CD63-labeled activated basophils was greater when higher concentrations of cefazolin than previously reported were used. In control subjects, however, the number of activated basophils by cefazolin stimulation was negligible regardless of its concentration. In the case of CD203c, the sensitivity was 86% with a cefazolin concentration of 3 mg/ml, while in the case of CD63, the sensitivity was 100% with a cefazolin concentration of 10 mg/ml. Using a higher concentration of cefazolin than previously reported for the BAT might increase the accuracy of diagnosis of cefazolin-induced anaphylaxis.