A 27-year-old female presents with easy fatigue and light-headedness. She also has a dry cough and fever for the past few days. On examination, she is pale, her lungs are clear, and the rest is normal. A chest x-ray (CXR) shows patchy bilateral infiltrates; the hemoglobin is 8.4 g/dL, reticulocyte count of 6%, and many spherocytes on the peripheral blood film. Which of the following is the most likely significance of the spherocytosis on the blood film?