A 16-year-old male presents with recurrent sinusitis, hemoptysis, and rapidly progressive glomerulonephritis. Laboratory studies are positive for antineutrophil cytoplasmic antibodies (ANCA). The pathogenesis of this vasculitis involves ANCA-mediated activation of neutrophils and monocytes. Which specific ANCA target antigen is most closely associated with this classic triad of upper airway, lower airway, and renal disease?