Background: Neutropenia is common after kidney transplantation and is associated with an increased incidence of infections. Drug toxicities are the main causes of posttransplant neutropenia (PTN), mainly related to immunosuppressive drugs as mycophenolic acid (MPA) and anti-infectious agents, but some PTN remain unexplained.
Methods: Between January 2012 and January 2013, cultures of autologous granulocytic progenitors from bone marrow aspirate were performed in two patients with unexplained severe neutropenia.
Results: Both patients' serum inhibited granulocytic differentiation while granulocytic differentiation was normal with the control serum. Similar inhibition of differentiation of granulocytic progenitors from a control marrow was observed with the patients' serum as compared with the control serum. Moreover, in both cases intravenous immunoglobulins allowed full neutrophil count recovery. Other usual etiologies of acquired neutropenia including systemic drug toxicity, infection, and autoimmune disease were excluded. As frequently observed in adult immune neutropenia, granulocyte autoantibodies were absent in both cases. Owing to biological and clinical results, we concluded that an autoimmune mechanism was responsible for neutropenia. The levels of MPA, which is known to interact with tacrolimus, were not measured in our patients. However, the persistence of neutropenia more than 70 days after withdrawal of MPA did not support this hypothesis.
Conclusion: Autoimmune neutropenia should be considered in kidney transplant recipients in case of persistent unexplained neutropenia as it allows effective treatment and avoids the withdrawal of important immunosuppressive and anti-infectious treatments.