Granulocyte Transfusion

Key points

Introduction

The term granulocyte is broadly applicable to white blood cells (WBCs) demonstrating cytoplasmic granules, referring not only to neutrophils, but also basophils, eosinophils, and mast cells. The latter 3 cell types rarely circulate in large numbers but are integral to the host defense against parasitic infections, allergens, and noxious stimuli. Neutrophils are by far the most numerous granulocyte and play a critical role in the immune defense against fungal and bacterial pathogens. ¹ Patients with impaired neutrophil function, either as a result of congenital deficits, neonatal infection, or as a result of chemotherapy or hematopoietic progenitor cell transplant, are at significant risk of morbidity and mortality after infection from an invasive pathogen. The development of bacterial and/or fungal infection in neutropenic patients is known to be associated with prolonged hospitalization, end-organ damage, and increased mortality. Furthermore, prolonged neutropenia is a poor prognostic indicator after hematopoietic progenitor cell transplantation. ^2 , 3

The transfusion of allogeneic granulocytes to provide innate immune support represents a logical therapeutic modality for patients with innate immune depression. However, the clinical usefulness of granulocyte transfusion (GTX) has long been debated, with reports suggesting clinical usefulness published as early as the 1930s. ⁴ To date no randomized controlled clinical trials have demonstrated the efficacy of GTX. ^5 , 6 However, some retrospective and observational studies suggest GTX may improve outcomes in specific populations of neutropenic patients with active infection. 7891011

Unfortunately, the interpretation of the studies performed to date has been hampered by multiple limitations, particularly those associated with variances in granulocyte collection, including, but not limited to, the evolution of donor stimulation and collection regimens, profound advancements, and modifications to patient care regimens, and poor patient accrual potentially owing to physician bias and an unwillingness to subject patients to randomization. ¹⁰ Herein we provide a practical guide for practice of GTX.