Immunology of a serum sickness/vasculitis reaction secondary to streptokinase used for acute myocardial infarction.

We have studied six patients who received streptokinase for acute myocardial infarction (MI). One of these patients experienced a serum sickness/vasculitis reaction nine days after receiving the drug. Immunologic investigation of serum obtained from these individuals demonstrated that IgE and IgG anti-streptokinase antibody concentrations (measured by radioimmunoassay) were significantly elevated, both pre and post (IgE antibody, 36-fold increase) drug exposure, in the individual having the serum sickness/vasculitis reaction. Two of five of the remaining MI patients receiving the drug had post-exposure elevation of IgE anti-streptokinase antibody, but no patient had the immunologic profile seen in the individual with vasculitis. One should be aware that the serum sickness/vasculitis reaction can occur late after administration of streptokinase when the acute MI patient is recuperating.