1. A 47-year-old male presents with declining renal function characterized by oliguria, elevated blood urea nitrogen and creatinine, and hematuria . He also complains of nasal congestion and epistaxis. Review of systems is notable for occasional cough and hemoptysis. Examination shows mucosal ulceration and nasal septal perforation, but no polyps. Which of the following serum markers would likely be present in this case?