Anaphylactic transfusion reactions in haptoglobin-deficient patients with IgE and IgG haptoglobin antibodies.

Background: Patients with haptoglobin deficiency associated with haptoglobin IgG antibodies, who experienced severe nonhemolytic transfusion reactions (NHTRs), have been identified in Japan. Haptoglobin deficiency therefore might be a risk factor for NHTRs.

Study Design And Methods: A total of 4138 cases of voluntarily reported NHTRs in Japan, including 367 cases of immediate-onset anaphylactic NHTRs, were examined to identify haptoglobin deficiency.