A 50-year-old male presents with edema and oliguria for 1 week. BP 160/100 mmHg, urinary protein 3g/24h, urinary RBCs 20-30/HPF, creatinine (Cr) 633 μmol/L, blood CIC (+). Renal pathology: Light microscopy shows 17 glomeruli with partial capillary narrowing, 6 cellular crescents, and 8 fibrocellular crescents. IgG and C3 show granular deposits along capillary walls and mesangial areas. The primary pathogenesis is: