Purpose of review: Inconsistent results regarding the clinical efficacy of granulocyte transfusions for the treatment or prophylaxis of life-threatening infections in neutropenic patients have been attributed to insufficient number of transfused neutrophils. Since the introduction of granulocyte colony-stimulating factor (G-CSF) to the granulocyte mobilization regimen in the 1990s, the number of transfused cells significantly increased, which directly translated to a significant increase in absolute neutrophil counts in the transfused patients.
Recent findings: For therapeutic granulocyte transfusions, neither of the two randomized controlled studies in the G-CSF era could demonstrate a clear clinical benefit. However, a number of small studies or case series have suggested its clinical efficacy, including one that demonstrated the clinical response against drug-resistant invasive fusariosis. For prophylactic granulocyte transfusions, there have been scarce reports in the G-CSF era. A pulmonary reaction is the most significant adverse event after granulocyte transfusions, although its reported frequency varies among studies.
Summary: Despite the expectation that the increased number of transfused neutrophils enables the clear demonstration of the clinical benefit, the role of therapeutic granulocyte transfusions remains controversial. Future directions may include: identifying the patient population who would benefit most from granulocyte transfusions; minimizing the risk of adverse events by identifying the risk factors and the prevention methods; and finding a way to prove the clinical benefit of granulocyte transfusions in therapeutic and prophylactic settings.