Recurrent IgA Nephropathy or Subclinical Chronic Humoral Rejection With Predominance of Plasma Cells: A Case Report.

Both antibody-mediated rejection and recurrence of kidney disease are major causes of allograft loss. A possible strategy to address the former is donor-specific antibody (DSA) monitoring. In this patient with IgA nephropathy, DSA detection triggered biopsy 10 years after transplant despite preserved graft function and normal urinary examination. Biopsy showed mild glomerulitis, mild capillaritis, and transplant glomerulopathy with no C4d peritubular capillary staining, along with IgA-dominant mesangial immunofluorescence staining. Interstitial inflammation had a notable predominance of plasma cells, a finding that has been variably attributed to rejection and worse prognosis. Immunosuppression was optimized with the working diagnosis of recurrent IgA nephropathy and/or chronic active humoral rejection with predominance of plasma cells, with favorable response at follow-up. This case illustrates the conflicting role of DSA monitoring and allograft biopsy to optimize immunosuppression management. Despite imperfect correlation with each other and clinical outcomes, they are key to tailor therapy. In the future, characterization of the role of plasma cell infiltrates in rejection might further enable prognosis and treatment individualization.