Detection of specific IgE to quinolones

In the last years, immediate reactions to quinolone antibiotics have been observed with increasing frequency, mainly urticaria, angioedema, and shock. No test was available because of the high incidence of false-positive results on skin tests. Thus the pathogenesis, value of diagnostic procedures, and cross-reactivity have not been evaluated in a systematic way.

We sought to assess whether these reactions are IgE mediated and whether an in vitro test for quinolone-specific IgE is useful in the diagnosis and understanding of cross-reactivity.

We assayed specific serum IgE to quinolones using epoxy-activated sepharose 6B as the solid phase in 55 patients with immediate adverse reactions; specificity of IgE binding was demonstrated by inhibition tests.

The test yielded positive results in 30 (54.5%) patients who were tested 1 to 48 months after the reaction had occurred. The quinolone-specific IgE seems to disappear more slowly in atopic patients. The cross-reactivity between various quinolones allowed us to identify a common structural motif within quinolones that might be responsible for clinical and serologic cross-reactivity.

A substantial portion of immediate reactions to quinolones appear to be IgE mediated. Cross-reactivity of IgE among different quinolones is frequent and suggests that a common avoidance of quinolones should be attempted in all patients with respective symptoms.