Autoimmunity in infection-related glomerulonephritis

Introduction: Autoimmune (AI) reactivity in the setting of infection-related GN (IRGN) is often viewed as an epiphenomenon and not well described. Methods: We report a cohort of 17 patients with IRGN during a 7-year period that highlights cases with AI reactivity and describes the clinical and pathologic characteristics of IRGN cases associated with AI reactivity. Results: Of the IRGN cases, 76% had clinical evidence of an autoimmune diseases (AD) and/or positive autoimmune serologies. Within the IRGN group with AI reactivity, 12 had positive autoimmune serologies (92%) and 10 had AD (77%). 30% had a prior diagnosis of AD, while the remaining 70% did not have a history of AD and were either diagnosed or suspected of having an AD at the time of biopsy. The most common autoantibody detected was anti-nuclear antibody (ANA) followed by anti-neutrophil cytoplasmic antibodies (ANCA) and autoantibodies associated with anti-phospholipid syndrome. Conclusion: The study is not sufficiently powered to determine any significance but demonstrates the frequency with which autoimmune features occur in IRGN and should prompt further future investigation. In summary, our findings suggest autoimmune manifestations are common in IRGN.