Abstract Introduction Anti-glomerular basement membrane (anti-GBM) disease is an uncommon autoimmune condition characterized by rapidly progressive glomerulonephritis (RPGN), often associated with pulmonary involvement. A rare subset of patients exhibits dual positivity for anti-GBM and antineutrophil cytoplasmic antibodies (ANCA), typically myeloperoxidase (MPO)-ANCA, suggesting overlapping pathogenic mechanisms. Environmental or immune triggers such as infections, toxins, or insect stings have been postulated to initiate autoimmune responses in genetically susceptible individuals. We present a case of dual anti-GBM and MPO-ANCA-associated crescentic glomerulonephritis triggered by multiple bee stings (18-20 at once). Case Presentation A 77-year-old female with a medical history of atrial fibrillation on Eliquis, hypertension, hyperlipidemia, obstructive sleep apnea on CPAP, and chronic kidney disease stage III presented with one week of generalized weakness and poor appetite. She denied fever, abdominal pain, cough, or urinary symptoms. Notably, she reported multiple bee stings approximately six weeks prior to the presentation. On admission, she was found to have high anion gap metabolic acidosis, anemia (Hgb 7.4 g/dL), acute kidney injury (BUN 257 mg/dL, Cr 31.9 mg/dL, GFR 0 mL/min), and hyperkalemia (K⁺ 8.1 mmol/L). CT abdomen/pelvis showed diffuse body wall, mesenteric, and retroperitoneal edema without acute findings. She was admitted to the ICU and started on continuous renal replacement therapy (CRRT). Autoimmune evaluation revealed dual antibody positivity with elevated anti-GBM (+4.7) and MPO-ANCA (5.8, P-ANCA 1:320). Kidney biopsy showed focal necrotizing and diffuse crescentic glomerulonephritis with moderate chronicity, consistent with anti-GBM nephritis (MPO-ANCA type). CT chest suggested pulmonary edema, and bronchoscopy confirmed diffuse alveolar hemorrhage. She was treated with high-dose IV methylprednisolone (500 mg-1 g daily ×3 days, then 70 mg daily), plasmapheresis, and cyclophosphamide. Discussion Bee sting can trigger robust immune responses, including neutrophil activation. In the context of ANCA vasculitis, activated neutrophils release proteinases that digest components of GBM, notably, collagen type IV. This process exposes previously hidden cryptic epitopes. This leads to intermolecular epitope spreading and antibody production. This case illustrates a rare presentation of dual anti-GBM and MPO-ANCA-associated vasculitis, potentially triggered by multiple bee stings. Early recognition of environmental triggers and prompt immunosuppressive therapy are crucial to improving outcomes in these severe cases. This abstract is funded by: none
Singh et al. (Fri,) studied this question.