Anaphylactic reactions to aprotinin reexposure in cardiac surgery: relation to antiaprotinin immunoglobulin G and E antibodies.

BACKGROUND: Aprotinin, a serine proteinase inhibitor, reduces bleeding during cardiac surgery. As aprotinin is derived from bovine lung, it has antigenic properties. This investigation examined the incidence of anaphylactic reactions in patients reexposed to aprotinin and the relation to preformed antiaprotinin immunoglobulin (Ig)G and IgE antibodies.
METHODS: This prospective observational study conducted at five centers in Germany evaluated patients undergoing repeat cardiac surgery reexposed to aprotinin between 1995 and 1996. Antiaprotinin IgG and IgE antibody measurements, using a noncommercial enzyme-linked immunosorbent assay and an immunofluorescence assay, respectively, were performed preoperatively and postoperatively. An anaphylactic reaction was defined as major changes from baseline within 10 min of aprotinin administration of systolic pressure 20% or greater, heart rate 20% or greater, inspiratory pressure greater than 5 cm H2O, or a skin reaction.
RESULTS: In 121 cases (71 adults, 46 children), a mean aprotinin reexposure interval of 1,654 days (range, 16-7,136 days) was observed. Preoperative antiaprotinin IgG (optical density ratio > 3) and IgE antibodies (radioallergosorbent test [RAST] score < 3) were detected in 18 and 9 patients, respectively. High concentrations of each (IgG, optical density ratio > 10; IgE, RAST score > or = 3) were detected in five patients. Three patients (2.5%; 95% confidence interval, 0.51-7.1%) experienced an anaphylactic reaction after aprotinin exposure, followed by full recovery; these patients had reexposure intervals less than 6 months (22, 25, and 25 days) and the highest preoperative IgG concentrations of all patients (P < 0.05). Assay sensitivity was 100%, as no anaphylactic reactions occurred in IgG-negative patients (95% confidence interval, 0.0-3.1%); assay specificity was 98%. Preoperative IgE measurements were quantifiable in two of three reactive patients and in three nonreacting patients.
CONCLUSIONS: Quantitative detection of antiaprotinin IgE and IgG lacks specificity for predictive purposes; however, quantitation of antiaprotinin IgG may identify patients at risk for developing an anaphylactic reaction to aprotinin reexposure.