rhG-CSF does not affect the phenotype of adult donor peripheral blood NK cells

Effects and safety of granulocyte colony-stimulating factor in healthy volunteers

PURPOSE OF REVIEW

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is now widely used in normal donors for collection of peripheral blood progenitor cells for allogeneic transplantation and granulocytes for transfusion. Currently available data on biologic and molecular effects, and safety of rhG-CSF in normal healthy volunteers are reviewed.

RECENT FINDINGS

In addition to its known activating role on neutrophil kinetics and functional status, rhG-CSF administration can affect monocytes, lymphocytes and the hemostatic system. Granulocyte colony-stimulating factor receptors were identified in a variety of nonmyeloid tissues, although their role and functional activity have not always been well defined. Moreover, rhG-CSF is capable of modulating complex cytokine networks and can impact the inflammatory response. In addition to its known mobilizing role for peripheral blood progenitor cells, rhG-CSF can mobilize dendritic and endothelial progenitor cells as well. On a clinical level, serious rhG-CSF-related adverse events are well described (e.g. splenic rupture) but remain rare.

SUMMARY

rhG-CSF effects in healthy volunteers, although normally transient and self-limiting, are now believed to be more complex and heterogeneous than previously thought. Although rhG-CSF administration to healthy volunteers continues to have a favorable risk-benefit profile, these new findings have implications for safeguarding the safety of normal individuals.

Biologic and molecular effects of granulocyte colony-stimulating factor in healthy individuals: recent findings and current challenges

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used in healthy donors for collection of peripheral blood progenitor cells (PBPCs) for allogeneic transplantation and granulocytes for transfusion. The spectrum of its biologic and molecular activities in healthy individuals is coming into sharper focus, creating a unique set of challenges and clarifying the need to monitor and safeguard donor safety. Accumulating evidence indicates that rhG-CSF effects are not limited to the myeloid cell lineage. This may reflect the presence of functional G-CSF receptors on other cell types and tissues, as well as rhG-CSF-induced modulation of cytokine networks. While most rhG-CSF-induced effects are transient and self-limiting, preliminary, provocative data have suggested the possibility of a more durable effect on the chromosomal integrity of lymphocytes. While these reports have not been validated and have been subject to criticism, they are prompting prospective studies and monitoring efforts to determine whether there is a significant risk of long-term adverse events (eg, hematologic malignancies) in healthy PBPC and granulocyte donors. Based on the totality of information that is currently available, the administration of rhG-CSF to healthy donors for the purpose of PBPC donation continues to have a favorable risk-benefit profile.

Adenovirus infection after allogeneic stem cell transplantation

Adenovirus infection after allogeneic hematopoietic stem cell transplantation (HSCT) is an emerging pathogen causing relevant morbidity and mortality, with preponderance in children. During the last years, basic research on the biology of the virus and host immune response ameliorated the diagnostic, surveillance, and therapeutic strategies. Risk factors for infection commonly have an impact on T-cell reconstitution, such as T-cell depleted graft, unrelated or HLA-mismatched donor transplantation, and GvHD. Weekly surveillance by PCR in stool and blood till day 100 or longer post-HSCT and pre-emptive therapy with cidofovir are the mainstay of the current approach to adenoviral infections post-HSCT. Since a sufficient host T-cell response is essential to clear the virus, diagnostic procedures for detection of virus-specific T-cells have recently been developed to assess the risk of the infection. Furthermore, adoptive immunotherapy is a new treatment option for patients with absent specific T-cell response and present systemic adenoviral infection.

Natural-killer-cell-based treatment in haematopoietic stem-cell transplantation

Adoptive immunotherapy using natural killer (NK) cells is currently under investigation, especially in situations where anti-neoplastic effect is needed but infusion of T cells is considered hazardous, such as in recipients of haematopoietic stem-cell transplantation (HSCT) from haploidentical donors. NK-cell therapy is mainly but not exclusively investigated in the setting of allogeneic stem-cell transplantation. NK cells may induce potent anti-leukaemic and possibly anti-rejection activity, and may even mitigate graft-versus-host disease (GvHD). It remains to be determined whether such effects are clinically important and whether or not they are mediated mainly or exclusively by KIR-HLA class I interactions. Recent advances in graft engineering has provided methods for isolating large numbers of purified NK cells. Several groups have shown that clinical-grade NK cells at doses up to 10(7)/kg may be collected and purified for the purpose of infusion to patients. Early results in a limited number of patients show that these cell doses may be administered without adverse events and possibly without inducing GvHD. Further study is required to determine whether such infusions will be useful in preventing graft rejection, exerting graft-versus-leukaemia effects, and/or hastening immune recovery.