A 62-year-old woman with diabetes mellitus and hyperlipidemia is admitted 48 hours after the onset of acute anterior wall myocardial infarction. She underwent successful primary percutaneous coronary intervention (PCI) to the left anterior descending artery. On day 5 post-MI, she develops sudden-onset dyspnea, hypotension (BP 88/55 mmHg), and elevated JVP. Cardiac auscultation reveals a pericardial friction rub. Echocardiography shows a large pericardial effusion with diastolic right atrial collapse. A bedside pericardiocentesis is performed. Which of the following findings in the pericardial fluid would be most consistent with the pathological process occurring in this patient?