The role of type I hypersensitivity reaction and IgE-mediated mast cell activation in acute interstitial nephritis

Background: Acute interstitial nephritis (AIN) presents with acute kidney injury, with evidence of interstitial inflammation and tubulitis on histology, and the presence of fever, rash, and eosinophiluria. Although the pathogenesis of this disease is not well understood, cell-mediated immunity is thought to play a major role. We hypothesized that IgE mediated mast cell activation is also involved in the pathogenesis of renal injury in AIN. Methods: 28 patients, with biopsy proven AIN over a 5-year period, were included in this study. Clinical data, including renal outcomes and the etiologies of AIN, were evaluated in all patients. Available tissues (renal biopsy) from 26 of the patients were stained for ß-tryptase (marker for mast cell degranulation), IgE, IL-16, and CD3. A negative control for immunostaining was included. Results: Samples from all 26 individuals stained positive for ß-tryptase (mean of 11.16 cells/high power field), IgE (mean average of 0.68 cells/HPF), IL-16 (28% of the interstitium), and CD3 (33% of the interstitium). Acute interstitial nephritis was due to medication in 73%, systemic disease in 15%, and unknown (idiopathic) in 12% of the cases. 86% of patients were treated with corticosteroids. 18% required acute inpatient dialysis, with 7% remaining on dialysis longterm. Conclusions: Our study suggests that IgE and mast cell activation may play a role in the pathogenesis of AIN.