Review Question - QID 106690

A 56-year-old male undergoes a pancreaticoduodenectomy for resection of a tumor of the head of the pancreas. His medical history is otherwise insignificant except for a series of minor respiratory and gastrointestinal infections since childhood that were effectively treated with antibiotics. Before today, he has not had any prior surgeries or required a blood transfusion. In the post anesthesia care unit, his hemoglobin is measured and found to be 5.2 g/dL. A transfusion of 2 units of packed red blood cells is ordered. Minutes after the transfusion is initiated, the patient reports severe itching, nausea, and shortness of breath. His vital signs show a drop in blood pressure from 138/88 to 92/47 and an increase in heart rate from 94 to 118. The patient's nurse stops the transfusion immediately. Which of the following underlying conditions most likely predisposed this patient to develop this reaction?