Immunologic evaluation of ofloxacin hypersensitivity.

Quinolone hypersensitivity, most of which is immediate type, is rare but has increased in recent years. The pathogenic mechanisms underlying immediate reactions are not defined clearly. This study was aimed to observe the clinical characteristics of immediate hypersensitivity to ofloxacin and to investigate the pathogenic mechanism with detection of serum specific IgE to ofloxacin using an enzyme-linked immunoasorbent assay (ELISA). We recruited 5 patients with immediate hypersensitivity reactions to ofloxacin (group I), and as control groups, 5 subjects with ciprofloxacin hypersensitivity (group II) and 20 healthy subjects with no history of drug allergy. Serum specific-IgE to ofloxacin-human serum albumin (HSA) conjugate was detectable in four group I subjects (80%) and three group II subjects (60%). The ELISA inhibition test showed significant inhibition with both ofloxacin-HSA conjugate and free ofloxacin in a dose-dependent manner. As to ciprofloxacin, significant inhibition was noted upon addition of free ciprofloxacin in one subject, while minimal inhibition was noted in the other. We confirmed that an IgE-mediated response is a major pathogenic mechanism of ofloxacin hypersensitivity. Cross reactivity between ofloxacin and ciprofloxacin was noted with individual difference.