The Role of Granulocyte Transfusions in Hematopoietic Cell Transplantation and Leukemia

Overview

Granulocyte transfusions have been explored for over 50 years as a method to reduce infection risk in patients with low granulocyte counts, particularly in hematopoietic cell transplantation and leukemia. Despite early promise and technological advances in granulocyte collection, randomized trials have not demonstrated clear safety or efficacy benefits, leading to controversy and decreased clinical use.

Background

Infection risk increases significantly when blood granulocyte concentrations fall below 0.5 × 10⁹/L, prompting investigation into granulocyte transfusions as a potential remedy. Early devices like the NCI/IBM Amino™ Continuous Flow Blood Separator enabled collection of granulocytes from normal donors and those with chronic myeloid leukemia. Initial animal studies and small human trials suggested possible benefits, but larger randomized controlled trials failed to show consistent improvements in infection rates, remission, or survival. Complications such as transfusion reactions, allo-immunization, and pulmonary issues further complicated their use.

Data Highlights

Key Findings

• Infection risk rises sharply when granulocyte counts fall below 0.5 × 10⁹/L, but the exact threshold for transfusion benefit remains unclear.
• Granulocyte transfusions can be collected using continuous flow centrifugation, yielding 0.3–6 × 10¹⁰ granulocytes from normal donors and up to 10¹¹–10¹² from CML donors.
• Early animal and small human studies suggested granulocyte transfusions might improve infection outcomes, but larger trials showed no survival benefit.
• Prophylactic granulocyte transfusions during AML induction chemotherapy did not reduce infections or improve remission and were associated with increased pulmonary complications and transfusion reactions.
• High rates of allo-immunization and adverse interactions with antifungal agents like amphotericin limit granulocyte transfusion safety and efficacy.
• Use of granulocyte transfusions has declined markedly since the late 1990s, remaining a niche practice without consensus guidelines.

Clinical Implications

Current evidence does not support routine prophylactic or therapeutic granulocyte transfusions in hematopoietic cell transplantation or leukemia patients due to lack of demonstrated survival benefit and notable risks. Clinicians should weigh potential transfusion reactions, allo-immunization, and pulmonary complications against uncertain efficacy. Ongoing expert discussions may help clarify specific clinical scenarios where granulocyte transfusions could be considered.

Conclusion

Despite intuitive rationale and technological advances, granulocyte transfusions have not proven convincingly safe or effective in reducing infection-related morbidity or mortality in hematopoietic cell transplantation and leukemia. Their use remains controversial and limited pending further consensus and evidence.

References

1. Bodey & Freireich, 1965 -- Relationship between blood granulocyte concentration and infection risk
2. Epstein et al., 1969 -- Granulocyte transfusion prolongs survival in experimental bacteremia
3. Herzig et al., 1977 -- Randomized controlled trial of granulocyte transfusions in granulocytopenic patients
4. Powles et al., 1970s -- AML cell collection for immunotherapy
5. Recent large RCT in AML induction chemotherapy -- Granulocyte transfusions do not improve outcomes
6. American Society of Transplantation and Cellular Therapy (ASCT) Sub-Committee discussions, 2021