CD4(+) CD28(+) lymphocytes on day 5 after high-dose melphalan for multiple myeloma predict a low risk of infections during severe neutropenia and are associated with the number of reinfused T lymphocytes of the autologous stem cell graft

Mobilized peripheral blood grafts include more than hematopoietic stem cells: the immunological perspective

Although stem cell mobilization has been performed for more than 20 years, little is known about the effects of mobilizing agents on apheresis composition and the impact of graft cell subsets on patients' outcome. With the increasing use of plerixafor and the inclusion of poor mobilizers in autologous transplant procedures, new parameters other than CD34(+) stem cell dose are emerging; plerixafor seems to mobilize more primitive CD34(+)/CD38(-) stem cells compared with G-CSF, but their correlation with stable hematopoietic engraftment is still obscure. Immune recovery is as crucial as hematopoietic reconstitution, and higher T and natural killer cells infused within the graft have been correlated with better outcome in autologous transplant; recent studies showed increased mobilization of immune effectors with plerixafor compared with G-CSF, but further data are needed to clarify the clinical impact of these findings. In the allogeneic setting, much evidence suggests that mobilized T-cell alloreactivity is tempered by G-CSF, probably with the mediation of dendritic cells, even though no clear correlation with GVL and GVHD has been found. Plerixafor is not approved in healthy donors yet; early data suggest it might mobilize a GVHD protective balance of immune effectors, but further studies are needed to define its role in allogeneic transplant.

Changing treatment paradigms for patients with plasma cell myeloma: impact upon immune determinants of infection

Plasma cell myeloma (PCM) is increasing in prevalence in older age groups and infective complications are a leading cause of mortality. Patients with PCM are at increased risk of severe infections, having deficits in many arms of the immune system due to disease and treatment-related factors. Treatment of PCM has evolved over time with significant impacts on immune function resulting in changing rates and pattern of infection. Recently, there has been a paradigm shift in the treatment of PCM with the use of immunomodulatory drugs and proteasome inhibitors becoming the standard of care. These drugs have wide-ranging effects on the immune system but their impact on infection risk and aetiology remain unclear. The aims of this review are to discuss the impact of patient, disease and treatment factors on immune function over time for patients with PCM and to correlate immune deficits with the incidence and aetiology of infections seen clinically in these patients. Preventative measures and the need for clinically relevant tools to enable infective profiling of patients with PCM are discussed.

CD34+ cell subclasses and lymphocyte subsets in blood grafts collected after various mobilization methods in myeloma patients

BACKGROUND

Cyclophosphamide (CY) combined with granulocyte-colony-stimulating factor (G-CSF) is commonly used to mobilize stem cells in multiple myeloma (MM). Plerixafor may also be used with G-CSF in patients who mobilize poorly or it may be added to chemomobilization to boost mobilization. Limited data are available on graft content collected after various mobilization methods.

STUDY DESIGN AND METHODS

Blood grafts collected from 21 MM patients were retrospectively analyzed. We analyzed CD34+ subclasses and lymphocyte subsets from cryopreserved grafts collected on the next morning after plerixafor injection in nine MM patients mobilized with G-CSF with (n = 5) or without preceding CY (n = 4). As controls we had the first collections from 12 MM patients mobilized with low-dose CY with G-CSF.

RESULTS

The proportion of the most primitive stem cells (CD34+CD133+CD38-) from all CD34+ cells in the graft was higher in the plerixafor-treated patients but there was no significant difference in the total number of these cells. The numbers of CD19+ B lymphocytes and natural killer cells were higher in patients collected after G-CSF plus plerixafor when compared to the patients mobilized with CY plus G-CSF. Early engraftment after high-dose melphalan was comparable between the groups.

CONCLUSION

Plerixafor appears to have effects on blood stem cell graft composition in myeloma patients. A higher number of grafts should be evaluated in regard to cellular content and longer follow-up of the patients is needed to evaluate the potential clinical impact of graft content.