Anaphylactoid reaction to imiglucerase, but not to alglucerase, in a type I gaucher patient

Imiglucerase, the recombinantly produced enzyme, is gradually replacing the human placental derived alglucerase in the treatment of gaucher patients. We describe the first case, to the best of our knowledge, of an anaphylactoid reaction to imiglucerase in a patient who tolerated alglucerase. The patient was diagnosed at the age of 2 4/12 years with anemia and hepatosplenomegaly. Over the years he had suffered from marked splenomegaly, thrombocytopenia and recurrent bleeding episodes. At the age of 24 he started treatment with imiglucerase. After 3 months of treatment, immediately after starting an infusion, he experienced flushing, cough, tachycardia, palpitation, chest pain and excessive sweating, which reoccurred on a consecutive administration. Substitution with alglucerase was tolerated well, with only mild rash when he was premedicated with benadryl. Immediate skin tests to alglucerase, imiglucerase and gelatin were negative. IgG against alglucerase was undetectable. The in vitro mast cell degranulation test was positive for alglucerase, imiglucerase heamaccel (a gelatin based plasma substitute, which is a component of imiglucerase). This sensitivity to imiglucerase but not to alglucerase, raises the question of future treatment for this patient, since the production of alglucerase may cease, once imiglucerase production will cover the need for replacement enzyme.