Anaphylactoid reaction to muromonab-CD3 in a pediatric renal transplant recipient.

Muromonab-CD3 (OKT3), a murine IgG2a antibody directed against the T3 (CD3) complex on mature lymphocytes, triggers adverse immune reactions. Anaphylactic reactions have occurred in patients exposed to OKT3 and are mediated by anti-OKT3 IgE antibodies. The reactions are not antibody mediated and can occur within seconds of administration of a mast cell secretogogue. A renal transplant recipient became hypotensive and hypoxic immediately after receiving her first dose of OKT3 and required advanced life support. Serum antibody tests were negative for anti-OKT3 IgG, IgE, and antimouse protein antibodies. To our knowledge, this is the first published report of a patient with an anaphylactoid reaction to the initial infusion of OKT3.