A 76-year-old woman is hospitalized following surgical repair of a femoral neck fracture. Two days after surgery, she experiences acute-onset shortness of breath and tachycardia. Pharmacologic therapy is administered in addition to a CT scan that confirms the diagnosis. One week later, her bloods are shown:
Hemoglobin 15 g/dL
Leukocytes 8,000/μL
Platelets 80,000/μL
The immunologic mechanism responsible for this patient’s condition is most closely similar to which of the following?