Erythromycin jaundice: diagnosis by an in vitro challenge test.

A 53-year-old housewife who had developed severe cholestatic hepatitis following the administration of erythromycin estolate therapy two-and-a-half years previously, was studied by an in vitro "challenge" test in which peripheral venous lymphocytes were cultured in the presence of erythromycin estolate, erythromycin stearate and erythromycin base. Evidence of blastogenesis was observed in response to erythromycin estolate, but not to erythromycin stearate of erythromycin base. This test thus provided evidence that the patient was "sensitized" to erythromycin estolate without exposing her to the risk of in vivo challenge. Furthermore, in contrast to previous studies, the findings provide evidence that erythromycin estolate jaundice is mediated by immunological mechanisms.