Case Study OneA 50-year-old female patient with systemic lupus erythematosus (SLE) is admitted to the hospital with evidence of hemolysis, including decreased hemoglobin and hematocrit, increased reticulocyte count, and increased indirect bilirubin. The patient has no recent history of transfusion. An antibody screen is ordered and 3+ agglutination is observed at the AHG phase for all cells. An au

A 50-year-old female patient with systemic lupus erythematosus (SLE) is admitted to the hospital with evidence of hemolysis, including decreased hemoglobin and hematocrit, increased reticulocyte count, and increased indirect bilirubin. The patient has no recent history of transfusion. An antibody screen is ordered and 3+ agglutination is observed at the AHG phase for all cells. An autologous control (autocontrol) is also tested and 3+ agglutination is observed at the AHG phase in this test as well.

Given the results of the antibody screen and other laboratory test results and the patient's medical and transfusion history, which of the following is the MOST likely cause of the positive screen results?