Single doses of intravenous protamine result in the formation of protamine-specific IgE and IgG antibodies

Background: Protamine reactions are a well-recognized and serious complication of intravenous protamine administration. IgE-mediated anaphylaxis occurs after initial sensitization and subsequent re-exposure to antigens. Subcutaneous protamine in insulin preparations is associated with protamine-specific IgE and IgG antibody production. In contrast, the influence of intravenous protamine administration on protamine-specific IgE and IgG antibody formation has never been investigated. Methods: Sera from 93 patients were analyzed for protamine-specific IgE and IgG antibodies both before and 4 to 6 weeks after exposure to single doses of intravenous protamine. Specific clinical variables were assessed by univariate and multivariate analyses to determine independent predictors of protamine- specific antibody production. Results: In patients who were previously seronegative, intravenous protamine administration resulted in protamine- specific IgE and IgG antibody production in 17 of 93 (18%) and 15 of 93 (16%) patients, respectively. As determined by multivariate analysis, male gender (p = 0.06) and insulin-dependent diabetes mellitus (p = 0.002) were associated with protamine-specific IgG but not IgE antibody production. Conclusion: Single-dose intravenous protamine resulted in protamine-specific IgE and/or IgG antibody production in 26 of 93 (28%) of patients. Seroconversion was associated with male gender and insulin-dependent diabetes mellitus. Patients responding immunologically to protamine may be at increased risk for experiencing reactions on subsequent exposure.