Immune reconstitution after transplantation of autologous peripheral CD34+ cells: analysis of predictive factors and comparison with unselected progenitor transplants

Strategic infection prevention after genetically modified hematopoietic stem cell therapies: recommendations from the International Society for Cell & Gene Therapy Stem Cell Engineering Committee

There is lack of guidance for immune monitoring and infection prevention after administration of ex vivo genetically modified hematopoietic stem cell therapies (GMHSCT). We reviewed current infection prevention practices as reported by providers experienced with GMHSCTs across North America and Europe, and assessed potential immunologic compromise associated with the therapeutic process of GMHSCTs described to date. Based on these assessments, and with consensus from members of the International Society for Cell & Gene Therapy (ISCT) Stem Cell Engineering Committee, we propose risk-adapted recommendations for immune monitoring, infection surveillance and prophylaxis, and revaccination after receipt of GMHSCTs. Disease-specific and GMHSCT-specific considerations should guide decision making for each therapy.

Immune reconstitution after transplantation of autologous peripheral stem cells in children: a comparison between CD34+ selected and nonmanipulated grafts

BACKGROUND AND AIMS

High-dose chemotherapy (HDC) followed by autologous stem cell transplantation (ASCT) improves the prognosis in pediatric patients with several solid tumors and lymphomas. Little is known about the reconstitution of the immune system after ASCT and the influence of CD34+ cell selection on the reconstitution in pediatric patients.

METHODS

Between 1990 and 2001, 94 pediatric patients with solid tumors and lymphomas received autologous CD34+ selected or unmanipulated peripheral stem cells after HDC. CD34+ selection was carried out with magnetic microbeads. The absolute numbers of T cells, B cells and natural killer (NK) cells were measured and compared in both groups at various time points post-transplant.

RESULTS

Recovery of T cells was significantly faster in the unmanipulated group at day 30, with no significant difference later on. Reconstitution of B and NK cells was similar in both groups without significant differences at any time. The CD34+-selected group was divided into patients receiving less or more than 5.385 × 106/kg CD34+ cells. Patients in the CD34+ high-dose group displayed significantly faster reconstitutions of neutrophiles and lymphocyte subsets than the CD34+ low-dose group.

CONCLUSIONS

Engraftment and reconstitution of leukocytes, B cells and NK cells after transplantation of CD34+ selected stem cells were comparable to that in patients receiving unmanipulated grafts. T-cell recovery was faster in the unmanipulated group only within the first month. However, this delay could be compensated by transplantation of >5.385 × 106 CD34+ cells/kg. Especially for patients receiving immunotherapy after HDC large numbers of immune effector cells such as NK and T cells are necessary to mediate antibody-dependent cellular cytotoxicity. Therefore, in patients receiving autologous CD34+-selected grafts, our data emphasize the need to administer high stem cell counts.

Approaches to Enhance Natural Killer Cell-Based Immunotherapy for Pediatric Solid Tumors

Treatment of metastatic pediatric solid tumors remain a significant challenge, particularly in relapsed and refractory settings. Standard treatment has included surgical resection, radiation, chemotherapy, and, in the case of neuroblastoma, immunotherapy. Despite such intensive therapy, cancer recurrence is common, and most tumors become refractory to prior therapy, leaving patients with few conventional treatment options. Natural killer (NK) cells are non-major histocompatibility complex (MHC)-restricted lymphocytes that boast several complex killing mechanisms but at an added advantage of not causing graft-versus-host disease, making use of allogeneic NK cells a potential therapeutic option. On top of their killing capacity, NK cells also produce several cytokines and growth factors that act as key regulators of the adaptive immune system, positioning themselves as ideal effector cells for stimulating heavily pretreated immune systems. Despite this promise, clinical efficacy of adoptive NK cell therapy to date has been inconsistent, prompting a detailed understanding of the biological pathways within NK cells that can be leveraged to develop "next generation" NK cell therapies. Here, we review advances in current approaches to optimizing the NK cell antitumor response including combination with other immunotherapies, cytokines, checkpoint inhibition, and engineering NK cells with chimeric antigen receptors (CARs) for the treatment of pediatric solid tumors.

Human NK Cells in Autologous Hematopoietic Stem Cell Transplantation for Cancer Treatment

Simple Summary

Natural killer (NK) cells are key elements of the innate immune system that have the ability to kill transformed (tumor and virus-infected) cells without prior sensitization. Hematopoietic stem cell transplantation (HSCT) is a medical procedure used in the treatment of a variety of cancers. The early reconstitution of NK cells after HSCT and their functions support the therapeutic potential of these cells in allogenic HSCT. However, the role of NK cells in autologous HSCT is less clear. In this review, we have summarized general aspects of NK cell biology. In addition, we have also reviewed factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells.

Abstract

Natural killer (NK) cells are phenotypically and functionally diverse lymphocytes with the ability to recognize and kill malignant cells without prior sensitization, and therefore, they have a relevant role in tumor immunosurveillance. NK cells constitute the main lymphocyte subset in peripheral blood in the first week after hematopoietic stem cell transplantation (HSCT). Although the role that NK cells play in allogenic HSCT settings has been documented for years, their significance and beneficial effects associated with the outcome after autologous HSCT are less recognized. In this review, we have summarized fundamental aspects of NK cell biology, such as, NK cell subset diversity, their effector functions, and differentiation. Moreover, we have reviewed the factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells and their receptor repertoire in this regard.

Gold nanoparticle-mediated bubbles in cancer nanotechnology

Microbubbles (MBs) have been extensively investigated in the field of biomedicine for the past few decades. Ultrasound and laser are the most frequently used sources of energy to produce MBs. Traditional acoustic methods induce MBs with poor localized areas of action. A high energy level is required to generate MBs through the focused continuous laser, which can be harmful to healthy tissues. As an alternative, plasmonic light-responsive nanoparticles, such as gold nanoparticles (AuNPs), are preferably used with continuous laser to decrease the energy threshold and reduce the bubbles area of action. It is also well-known that the utilization of the pulsed lasers instead of the continuous lasers decreases the needed AuNPs doses as well as laser power threshold. When well-confined bubbles are generated in biological environments, they play their own unique mechanical and optical roles. The collapse of a bubble can mechanically affect its surrounding area. Such a capability can be used for cargo delivery to cancer cells and cell surgery, destruction, and transfection. Moreover, the excellent ability of light scattering makes the bubbles suitable for cancer imaging. This review firstly provides an overview of the fundamental aspects of AuNPs-mediated bubbles and then their emerging applications in the field of cancer nanotechnology will be reviewed. Although the pre-clinical studies on the AuNP-mediated bubbles have shown promising data, it seems that this technique would not be applicable to every kind of cancer. The clinical application of this technique may basically be limited to the good accessible lesions like the superficial, intracavity and intraluminal tumors. The other essential challenges against the clinical translation of AuNP-mediated bubbles are also discussed.

Identification of the best-suited donor for generating virus-specific T cells

BACKGROUND AND OBJECTIVES

Administration of virus-specific T cells (VSTs) is a viable antiviral treatment strategy after allogeneic HSCT, even if conventional therapies fail. Third-party donors are often chosen for the generation of the VST product. The eligibility of the donor has to be tested in a rigorous donor screening procedure, since the isolation technology only targets pre-existing VSTs.

MATERIALS AND METHODS

In a period of 3 years, we performed 32 VST treatments for 28 patients. Targeting four different viruses, 284 healthy individuals underwent 417 donor screening procedures. VSTs were counted by flow cytometry detecting interferon-gamma (IFN-γ) producing T cells. Generation of the VSTs was performed from leukapheresis products in a fully automated and closed system using magnetic cell separation.

RESULTS

The mean circulating VST frequencies ranged from 0·006% to 0·328%. The average yield of viable VSTs in the product was 1·83·10₆ cells, while the average VST dose calculated for the patient's body weight was 4·63·10₄ /kg. The mean purity - percentage of VSTs within the T cells - of all T-cell products was 62·9%. Correlation was identified between the frequency of the VSTs in the peripheral blood of the donor and the VST numbers of the end product; the strongest correlation was seen for CMV.

CONCLUSION

This paper focuses on the T-cell donors, highlighting some key points on the donor selection process. Based on the findings in connection with the CMV therapies, peripheral VST seems to be the best predictor of the VST content of the final product administered to the patient.

Impaired lymphocyte reconstitution after autologous transplant is associated with apoptosis of CD8+ T cells and adverse clinical outcome

We noticed that the lymphocyte counts, after autologous hematopoietic stem cell transplantation, oscillated during the first 4 post-transplant months. Thereafter, the lymphocyte counts stabilized and segregated the patients into two groups, those who normalized their lymphocyte counts and those with prolonged lymphopenia. In both groups, the CD4 counts remained low for at least 6 months. However, in approximately half of the patient, the CD8 counts increased to normal or above normal values. Patients with prolonged lymphopenia had higher rates of lymphocytes' spontaneous apoptosis and the lymphocytes in patients who restored their counts expressed the intracellular CD14-derived MO2 epitope that protects the cells from apoptosis. These findings were translated to longer disease-free survival and overall survival in patients who restored the CD8 counts. Collectively, our data show that post-transplant lymphocytes that express intracellular CD14-MO2 epitope have survival advantage.

Hematopoietic stem cell transplantation in autoimmune disorders: From immune-regulatory processes to clinical implications

Autoimmune diseases are characterized by the development of autoreactive T- and B-cells targeting self-antigens, which eventually can result in chronic and persistent organ damage. The autologous hematopoietic stem cell transplantation (AHSCT) opened new avenues in the treatment of patients with severe, treatment-resistant autoimmune diseases. This paper reviews the immune-regulatory mechanisms behind AHSCT, and also summarizes the experiences of clinical practice related to the therapy in organ-specific and systemic autoimmune diseases. It seems that the intricate interplay of various immune competent cells with regulatory capacity control in a synergistic manner the repopulated immune system after AHSCT, which potentially leads to a significant clinical improvement in certain autoimmune diseases. However, the widespread use of AHSCT was intrinsically limited, due to the serious side-effects of conditioning treatment and relatively high treatment-related mortality; moreover, the development of new effective and safe therapeutic approaches and the dawn of biological agents further limited its indications in the last decade. Nevertheless, with an appropriate patient selection and increased experience of transplant centres, the risks can be minimized, and AHSCT remained still a reasonable choice in multiple sclerosis and systemic sclerosis when the conventional therapy failed and further progression of disease is inevitable.

All-in-one processing of heterogeneous human cell grafts for gene and cell therapy

Current cell processing technologies for gene and cell therapies are often slow, expensive, labor intensive and are compromised by high cell losses and poor selectivity thus limiting the efficacy and availability of clinical cell therapies. We employ cell-specific on-demand mechanical intracellular impact from laser pulse-activated plasmonic nanobubbles (PNB) to process heterogeneous human cell grafts ex vivo with dual simultaneous functionality, the high cell type specificity, efficacy and processing rate for transfection of target CD3+ cells and elimination of subsets of unwanted CD25+ cells. The developed bulk flow PNB system selectively processed human cells at a rate of up to 100 million cell/minute, providing simultaneous transfection of CD3+ cells with the therapeutic gene (FKBP12(V36)-p30Caspase9) with the efficacy of 77% and viability 95% (versus 12 and 60%, respectively, for standard electroporation) and elimination of CD25+ cells with 99% efficacy. PNB flow technology can unite and replace several methodologies in an all-in-one universal ex vivo simultaneous procedure to precisely and rapidly prepare a cell graft for therapy. PNB’s can process various cell systems including cord blood, stem cells, and bone marrow.

Fingerprints of transplant tolerance suggest opportunities for immunosuppression minimization

HLA incompatible organ transplant tolerance is the holy grail of transplantation. Stable engraftment of an HLA mismatched allograft and life-long tolerance induction, though feasible in highly selected cohorts with depletional protocols, is not ready for generalized application to the entire transplant recipient pool. It has thus been important to harness biomarkers that can uncover mechanisms and tools for monitoring HLA mismatched recipients that develop a state of operational tolerance, during accidental immunosuppression withdrawal secondary to problems of over-immunosuppression (infection or malignancy) or toxicity (mostly cosmetic or cardiovascular). A restricted and unpredictable group of patients can demonstrate a clinical state of operational tolerance, manifested by state of stable graft function of a graft with HLA mismatches between recipient and donor, intact immune responses to third party antigens and no measurable immunosuppression. These patients have served as the basis for the discovery of clinically correlative biomarkers, in distal biofluids (mainly blood), that can define the existing state of operational clinical tolerance. Operationally tolerant patients are rare, as withdrawal of immunosuppression most often results in rejection and graft loss. Nevertheless, operationally tolerant kidney, liver and heart allograft recipients have been reported. The presence of similar biomarker signature profiles in HLA mismatched transplant recipients on immunosuppression, suggests the feasibility of utilizing these biomarkers for educated immunosuppression minimization with a view to retaining immunological quiescence, while reducing the maintenance immunosuppression burden to a "safe" alloimmune threshold. Though clinical operational tolerance is rare, as immunosuppression cessation most often results in increased alloimmunity and rejection, the biomarker profile studies that have harnessed whole genome profiling suggest that the frequency of this state may be ~8% in kidney allograft recipients, and even more frequent in pediatric recipients and in liver transplantation: 25% in adult liver allograft recipients and ~60% in pediatric liver allograft recipients. In this review we discuss putative molecular mechanisms, cellular players and correlative biomarkers that have been developed through clinically associative studies of tolerant and non-tolerant patients. Through mechanisms of carefully constructed and monitored randomized, prospective clinical trials, the transplant community stands at the cusp of improved quality of recipient life through educated immunosuppression minimization.

Dual roles of autologous CD8+ T cells in hematopoietic progenitor cell mobilization and engraftment

BACKGROUND

Poor marrow cellularity alone cannot explain poor hematopoietic progenitor cell (HPC) mobilization. This study assessed the role of CD8+ T cells in HPC cell mobilization and engraftment.

STUDY DESIGN AND METHODS

Mobilization and engraftment were assessed in 192 autologous HPC donors. CD34+, CD4+, and CD8+ T-cell contents in apheresis products were evaluated. Using a chemotaxis assay, we assessed the effect of purified autologous CD8+ T cells from low and high mobilizers on HPC migration from high to low stromal cell-derived factor (SDF-1α) concentration gradients. We also assessed CD8+ T-cell content association with days to neutrophil engraftment.

RESULTS

The median number of CD34+ cells/kg was 4.7 × 10(6) . Patients were categorized according to their total CD34+ cell collection quartile distribution into low, moderate, and high mobilizers. We found that HPC products from low mobilizers contained more CD8+ T cells than HPC products from moderate and high mobilizers. Chemotaxis assays showed depletion of CD8+ T cells enhances HPC mobilization independent of SDF-1α concentration. Neutrophil engraftment analysis showed that the higher the CD8+ T-cell content per unit CD34+ cell, the faster the rate of engraftment.

CONCLUSION

Our findings suggest CD8+ T cells inhibit HPC mobilization and facilitate homing and engraftment.

NK cell-based immunotherapies in Pediatric Oncology

The past decade has seen several anticancer immunotherapeutic strategies transition from "promising preclinical models" to treatments with proven clinical activity or benefit. In 2013, the journal Science selected the field of Cancer Immunotherapy as the overall number-1 breakthrough for the year in all of scientific research. In the setting of cancer immunotherapy for adult malignancies, many of these immunotherapy strategies have relied on the cancer patient's endogenous antitumor T-cell response. Although much promising research in pediatric oncology is similarly focused on T-cell reactivity, several pediatric malignancies themselves, or the chemo-radiotherapy used to achieve initial responses, can be associated with profound immune suppression, particularly of the T-cell system. A separate component of the immune system, also able to mediate antitumor effects and less suppressed by conventional cancer treatment, is the NK-cell system. In recent years, several distinct immunotherapeutic approaches that rely on the activity of NK cells have moved from preclinical development into clinical testing, and some have shown clear antitumor benefit. This review provides an overview of NK cell-based immunotherapy efforts that are directed toward childhood malignancies, with an emphasis on protocols that are already in clinical testing.

Adoptive immunotherapy with antigen-specific T cells during extracorporeal membrane oxygenation (ECMO) for adenovirus-related respiratory failure in a child given haploidentical stem cell transplantation

We report on the successful infusion of human adenovirus (HAdV)-specific T cells in a child with congenital amegakaryocytic thrombocytopenia, given T-cell-depleted hematopoietic stem cell transplantation (HSCT) from the HLA-haploidentical mother during extracorporeal membrane oxygenation (ECMO) for severe HAdV-related respiratory failure. Donor-derived, interferon (IFN)-γ-secreting HAdV-specific T cells were enriched using the cytokine capture assay, after in vitro stimulation with overlapping peptides from the immunodominant HAdV5 hexon protein. Two weeks after T-cell transfer, viral load decreased and ECMO was discontinued. T-cell responses to HAdV antigens were documented after four weeks and were associated with viral clearance, immune reconstitution and clinical amelioration.

Plasmonic nanobubbles as tunable cellular probes for cancer theranostics

This review is focused on a novel cellular probe, the plasmonic nanobubble (PNB), which has the dynamically tunable and multiple functions of imaging, diagnosis, delivery, therapy and, ultimately, theranostics. The concept of theranostics was recently introduced in order to unite the clinically important stages of treatment, namely diagnosis, therapy and therapy guidance, into one single, rapid and highly accurate procedure. Cell level theranostics will have far-reaching implications for the treatment of cancer and other diseases at their earliest stages. PNBs were developed to support cell level theranostics as a new generation of on-demand tunable cellular probes. A PNB is a transient vapor nanobubble that is generated within nanoseconds around an overheated plasmonic nanoparticle with a short laser pulse. In the short term, we expect that PNB technology will be rapidly adaptable to clinical medicine, where the single cell resolution it provides will be critical for diagnosing incipient or residual disease and eliminating cancer cells, while leaving healthy cells intact. This review discusses mechanisms of plasmonic nanobubbles and their biomedical applications with the focus on cancer cell theranostics.

Changes in the number of CD8⁺ T lymphocytes in the peripheral blood of patients with various autoimmune diseases after autologous hematopoietic stem cell transplantations and their relations to the survival times

The changes in the number of CD8⁺ T lymphocytes were studied before (0 day) and then 30 days after the autologous hematopoietic stem cell transplantations (AHSCT) in 14 therapy refractory patients with autoimmune diseases. The years of survival and the clinical states were also evaluated. The number of CD8⁺ T cells was determined by an hematologic automat and by flow cytometry. Longer than 5-year survival times were found in 6 cases, whereas there was no progression (improvement) in 2 cases, and 4 patients were lost. The increase in the number of CD8⁺ cytotoxic T cells was gradual in the first 2 months and reached the significantly highest values among all subtypes of lymphocytes. It was of a special interest that in all the 4 patients who died, the numbers of CD8⁺ T cells were less than 150/μl on the 30th day after AHSCT, whereas all the 10 patients with a higher cell number survived. These results suggest that the early monitoring of the number (not only the ratio) of regenerating CD8⁺ T cells in the peripheral blood can be a useful and quantitative laboratory measurement after AHSCT, and it has a significant relation also to the survival times of transplanted patients.

Cell-specific multifunctional processing of heterogeneous cell systems in a single laser pulse treatment

Current methods of cell processing for gene and cell therapies use several separate procedures for gene transfer and cell separation or elimination, because no current technology can offer simultaneous multifunctional processing of specific cell subsets in highly heterogeneous cell systems. Using the cell-specific generation of plasmonic nanobubbles of different sizes around cell-targeted gold nanoshells and nanospheres, we achieved simultaneous multifunctional cell-specific processing in a rapid single 70 ps laser pulse bulk treatment of heterogeneous cell suspension. This method supported the detection of cells, delivery of external molecular cargo to one type of cells and the concomitant destruction of another type of cells without damaging other cells in suspension, and real-time guidance of the above two cellular effects.

Immunological reconstitution after autologous stem cell transplantation in patients with refractory systemic autoimmune diseases

OBJECTIVE

High-dose chemotherapy followed by autologous haematopoietic stem cell transplantation (AHSCT) can be a salvage therapy for patients with severe, refractory systemic autoimmune diseases. The function of the newly rebuilt immune system is important, but little is known about immune reconstitution after AHSCT in autoimmune disorders. Our aim was to investigate the repopulation of different lymphocyte subsets in patients with systemic autoimmune diseases after AHSCT.

METHODS

Twelve patients with severe refractory, autoimmune diseases were enrolled in the study: four with rheumatoid arthritis (RA), four with systemic sclerosis (SSc), three with systemic lupus erythematosus (SLE), and one with autoimmune overlap syndrome (myositis and RA). After stem-cell mobilization, CD34+ apheresis was carried out, followed by conditioning and AHSCT. After transplantation, peripheral lymphocyte subsets were regularly assessed by flow cytometry.

RESULTS

The follow-up time was 24 months. The overall transplantation-related mortality (TRM) was 16.7% and the transplant-related toxicity was 33% 2 years after AHSCT. Regarding the immune reconstitution, CD56+ natural killer (NK) cells appeared in the earliest phase after transplantation, followed by CD8+ T cells. B cells and CD4+ T cells became normal within 150 days. The ratio of naive cells was low 30 days after AHSCT; however, naive B cells regenerated within 2 months whereas the repopulation of naive T cells took longer. After a short increase, the ratio of memory cells decreased 2 months after transplantation. Regulatory T (Treg) cells did not change significantly in the peritransplant period. Altogether approximately 5-6 months were required for the reconstitution of the peripheral immune network.

CONCLUSIONS

AHSCT can be a salvage therapeutic modality in autoimmune patients who are refractory to other conventional therapies.

Immune Recovery of Lymphocyte Subsets 6 Years after Autologous Peripheral Blood Stem Cell Transplantation (PBSCT) for Lymphoproliferative Diseases. A Comparison between NHL, HD and MM in Group of 149 Patients

To evaluate the normalization of lymphocyte subsets several years after autologous peripheral blood stem cell transplantation (aPBSCT) and to detect any differences based on the underlying lymphoproliferative diseases, we analyzed the immunological recovery of 149 patients with Non Hodgkin's Lymphoma (NHL), Hodgkin's Disease (HD), Multiple Myeloma (MM). Lymphocyte recovery was assessed before the transplant, on days 15, 30, 60, 90, 120 and on years 1, 2, 4, 6. Analysis of a total of 709 lymphocytes, including total lymphocyte count, CD3 +, CD4 +, CD8 +, CD4 +/CD8 + ratio, CD19 +, CD3 + HLA-DR +, CD16 + 56 +, was performed. The normalization of total lymphocyte counts was achieved between days 14 to 22 following PBSCT. CD3 + cells count showed a normalization after 2 years in the HD and NHL groups and after 4 years in MM group. CD4 + subset achieved normalization during the sixth year in the 3 groups. The CD8 + and CD19 + lymphocytes subsets achieved normal values in the 3 groups at day 60 and at day 120 respectively. CD16 + 56 + and CD3 +/HLA-DR + lymphocytes showed median values above the normal range starting from day 30. Immunological recovery was similar in all 3 groups. Moreover, the recovery of all subsets evaluated was similarly demonstrated within 6 years after aPBSCT.

Prophylactic ciprofloxacin treatment prevented high mortality, and modified systemic and intestinal immune function in tumour-bearing rats receiving dose-intensive CPT-11 chemotherapy

Infectious complications are a major cause of morbidity and mortality from dose-intensive cancer chemotherapy. In spite of the importance of intestinal bacteria translocation in these infections, information about the effect of high-dose chemotherapy on gut mucosal immunity is minimal. We studied prophylactic ciprofloxacin (Cipro) treatment on irinotecan (CPT-11) toxicity and host immunity in rats bearing Ward colon tumour. Cipro abolished chemotherapy-related mortality, which was 45% in animals that were not treated with Cipro. Although Cipro reduced body weight loss and muscle wasting, it was unable to prevent severe late-onset diarrhoea. Seven days after CPT-11, splenocytes were unable to proliferate (stimulation index=0.10+/-0.02) and produce proliferative and inflammatory cytokines (i.e., Interleukin (IL)-2, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha) IL-1beta, IL-6) on mitogen stimulation in vitro (P<0.05 vs controls), whereas mesenteric lymph node (MLN) cells showed a hyper-proliferative response and a hyper-production of pro-inflammatory cytokines on mitogen stimulation. This suggests compartmentalised effects by CPT-11 chemotherapy on systemic and intestinal immunity. Cipro normalised the hyper-responsiveness of MLN cells, and in the spleen, it partially restored the proliferative response and normalised depressed production of IL-1beta and IL-6. Taken together, Cipro prevented infectious challenges associated with immune hypo-responsiveness in systemic immune compartments, and it may also alleviate excessive pro-inflammatory responses mediating local gut injury.

Antigen-Specific T-Cell Immunity in Multiple Myeloma Patients is Restored Following High-Dose Therapy: Implications for Timing of Vaccination

The present study analyses the influence of high-dose chemotherapy (HD) and autologous stem cell transplantation on natural and vaccine induced specific immunity in multiple myeloma patients. Peripheral blood was collected from six multiple myeloma (MM) patients at serial time points in connection with treatment and during a follow-up period of 3 months. T-cell response to cytomegalovirus (CMV), varicella zoster virus (VZV) and tetanus toxoid (TT) was determined by flow cytometry analysis for CD69, TNFalpha, IFNgamma, IL-4 expression and cell proliferation. At diagnosis and prior to induction chemotherapy TNFalpha expressing T cells in 5/6 patients were found specific for CMV, 3/6 for VZV and 4/6 for TT. Serial analyses during treatment conclude impaired immune response, however, 3 months post-transplantation all but one patient had regained cytokine expressing CD8(+) T cells specific for CMV, VZV and TT. The highest percentages of cytokine responding T cells were observed after stimulation with CMV antigen. A striking observation was the low cytokine reactivity (close to zero) measured in G-CSF mobilized blood at the time of leukapheresis. In spite of a general reduction of the CD4/CD8 ratio following transplantation, recovery of antigen specific CD4(+) T cells reactivity generally occurred prior to CD8(+) recovery and often to a higher level. In conclusion, the study demonstrates that natural as well as vaccine induced specific immunity present prior to HD was regained after stem cell transplantation, hence identifying a possible window for future vaccination trials.

Autologous hematopoietic stem cell transplantation in refractory celiac disease with aberrant T cells

Autologous hematopoietic stem cell transplantation (ASCT) is an increasingly accepted treatment for refractory autoimmune diseases. Refractory celiac disease with aberrant T cells (RCD type II) is unresponsive to available therapies and carries a high risk of transition into enteropathy associated T-cell lymphoma (EATL). This study reports on the feasibility, safety, and efficacy of ASCT in patients with RCD type II. Thirteen patients with RCD type II were evaluated. Seven patients (4 men, 3 women, mean age 61.5 years [range, 51-69 years]) underwent transplantation. After conditioning with fludarabine and melphalan, ASCT was performed. Patients were monitored for response, adverse effects, and hematopoietic reconstitution. All 7 patients completed the mobilization and leukapheresis procedures successfully and subsequently underwent conditioning and transplantation. Engraftment occurred in all patients. No major nonhematologic toxicity or transplantation-related mortality was observed. There was a significant reduction in the aberrant T cells in duodenal biopsies associated with improvement in clinical well-being and normalization of hematologic and biochemical markers (mean follow-up, 15.5 months; range, 7-30 months). One patient died 8 months after transplantation from progressive neuroceliac disease. These preliminary results showed that high-dose chemotherapy followed by ASCT seems feasible and safe and might result in long-term improvement of patients with RCD type II whose condition did not respond promptly to available drugs.

T-lymphocyte reconstitution following rigorously T-cell-depleted versus unmodified autologous stem cell transplants

We compared the kinetics of T-cell recovery after extensive ex vivo and in vivo T-cell depleted autologous stem cell transplantation (SCT) for multiple sclerosis (MS; n=8) with unmodified SCT for hematological malignancies (HM; n=39). Both patient group showed a very protracted recovery of 'naive' CD4(+), 45R0(-) ( approximately CD45RA(+)) T-cells. Within the 'primed' CD4(+), 45R0(+) T-cells, the 'central memory' cells expressing the CD62L and CD27 markers were the slowest to recover. The repopulating T-cells were highly activated, as shown by increased expression of HLA-DR and the apoptosis marker CD95. The capability of CD4(+) and CD8(+) T-cells to produce IFN-gamma, IL-2 and TNF-alpha had reached normal ranges from 2 months post SCT onwards. Unexpectedly, the kinetics of T-cell recovery between 3 and 12 months post transplant was similar in T-depleted and unmodified SCT. Before SCT, the HM patients showed lymphopenia of all T-cell subsets, upregulated HLA-DR and CD95 expression and increased cytokine responses. We suggest that the similar kinetics of T-cell recovery in the two patient groups may be explained by the susceptibility to apoptosis of the activated CD4(+) T-cells in the autografts of the HM patients. This susceptibility to apoptosis would interfere with a swift and sustained CD4(+) T-cell regeneration post SCT.

In vitro culture during retroviral transduction improves thymic repopulation and output after total body irradiation and autologous peripheral blood progenitor cell transplantation in rhesus macaques

Immunodeficiency after peripheral blood progenitor cell (PBPC) transplantation may be influenced by graft composition, underlying disease, and/or pre-treatment. These factors are difficult to study independently in humans. Ex vivo culture and genetic manipulation of PBPC grafts may also affect immune reconstitution, with relevance to gene therapy applications. We directly compared the effects of three clinically relevant autologous graft compositions on immune reconstitution after myeloblative total body irradiation in rhesus macaques, the first time these studies have been performed in a large animal model with direct clinical relevance. Animals received CD34(+) cell dose-matched grafts of either peripheral blood mononuclear cells, purified CD34(+) PBPCs, or purified CD34(+) PBPCs expanded in vitro and retrovirally transduced. We evaluated the reconstitution of T, B, natural killer, dendritic cells, and monocytes in blood and lymph nodes for up to 1 year post-transplantation. Animals receiving selected-transduced CD34(+) cells had the fastest recovery of T-cell numbers, along with the highest T-cell-receptor gene rearrangement excision circles levels, the fewest proliferating Ki-67(+) T-cells in the blood, and the best-preserved thymic architecture. Selected-transduced CD34(+) cells may therefore repopulate the thymus more efficiently and promote a higher output of naïve T-cells. These results have implications for the design of gene therapy trials, as well as for the use of expanded PBPCs for improved T-cell immune reconstitution after transplantation.

Immunity for tumors and microbes after autotransplantation: if you build it, they will (not) come

Relapses after autologous stem cell transplants for hematopoietic malignancies are frequent and post-transplant infections continue to cause significant post-transplant morbidity and even mortality. The post-transplant period is typically characterized by low lymphocyte counts and impaired immune cell function. Early restoration of immune function may contribute to better disease control and enhance protection from infections. Indeed the attainment of a 'minimal residual disease' status following high-dose therapy makes the early post-transplant period ideal for the introduction of antitumor immunotherapy. Attempts to generate immunity against tumor and microbial antigens after autotransplantation have included vaccinations, T cell infusions (both resting and activated) and combinations of vaccinations and adoptive T cell infusions. One successful strategy for generating robust immune responses against microbial antigens was the combination of pre and post-transplant immunizations along with an early (post-transplant) infusion of in vivo vaccine-primed and ex vivo co-stimulated autologous T cells. Whether this or similar strategies will lead to the generation of effective antitumor immunity is unknown. The lessons gained from efforts to rebuild immune system function in the setting of autotransplantation may also be applicable to the problem of restoring immunity in other immunodeficient groups such as patients with cancer or HIV disease and the elderly.

Autologous haematopoietic-stem-cell transplantation for multiple sclerosis

Intense immunosuppression followed by autologous haematopoietic-stem-cell transplantation (HSCT) is being assessed as a potential treatment for patients with severe multiple sclerosis (MS). The treatment was developed from research that showed autologous HSCT was as effective as allogeneic HSCT in the treatment of experimental autoimmune encephalomyelitis. The treatment is thought to eradicate the defective immune system, and the infused haematopoietic stem cells reconstitute an immune system that is more tolerant to the nervous system. About 250 patients with MS have been treated with autologous HSCT as part of phase I and phase II open trials. Autologous HSCT seems feasible in MS and assessment with clinical and MRI measures suggests it induces a profound and long-lasting suppression of inflammation. The course of MS seems to be stabilised after autologous HSCT, especially in ambulatory patients with evidence of active disease. Autologous HSCT deserves further study in randomised controlled trials.

Infused peripheral blood autograft absolute lymphocyte count correlates with day 15 absolute lymphocyte count and clinical outcome after autologous peripheral hematopoietic stem cell transplantation in non-Hodgkin's lymphoma

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in non-Hodgkin's lymphoma (NHL). Factors affecting ALC-15 remain unknown. We hypothesized that dose of infused autograft lymphocytes (A-ALC) directly impacts upon ALC-15. A total of 190 consecutive NHL patients received A-ALC between 1993 and 2001. The primary end point was correlation between A-ALC and ALC-15. A strong correlation was identified (r=0.71). A higher A-ALC was infused into patients achieving an ALC-15 > or =500/microl vs ALC-15 <500/microl (median of 0.68 x 10(9)/kg (0.04-2.21 x 10(9)/kg), vs 0.34 x 10(9)/kg (0.04-1.42 x 10(9)/kg), P<0.0001). The median follow-up for all patients was 36 months (maximum of 109 months). The A-ALC threshold was determined at 0.5 x 10(9)/kg. The median overall survival (OS) and progression-free survival (PFS) times were longer in patients who received an A-ALC >/=0.5 x 10(9)/kg vs A-ALC <0.5 x 10(9)/kg (76 vs 17 months, P<0.0001; 49 vs 10 months, P<0.0001, respectively). Multivariate analysis demonstrated A-ALC to be an independent prognostic indicator for OS and PFS. These data support our hypothesis that ALC-15 and survival are dependent upon the dose of infused A-ALC in NHL.

A preliminary analysis of the balance between Th1 and Th2 cells after CD34+ cell-selected autologous PBSC transplantation

BACKGROUND

CD34+ cell-selected autologous PBSC transplantation (CD34+ APBSCT) is a procedure used for the treatment of patients with malignant disease that is intended to eliminate residual tumor cells from autologous grafts. However, frequent infectious complications after CD34+ APBSCT can occur. A delay of recovery of the absolute number of CD4+ T cells after transplantation was reported to be one disadvantageous factor. As data on T-cell function after CD34+ APBSCT are scanty, we analyzed changes in T-helper cell 1 (Th1) and T-helper cell 2 (Th2) after CD34+ APBSCT to evaluate immune reconstitution.

METHODS

Twelve patients underwent APBSCT (CD34+APBSCT group, n=4, and unselected APBSCT, n=8). Peripheral blood (PB) samples were obtained at 2, 4, 8, 12 and 16 weeks after the transplantation. The dynamics of the Th1 and Th2 were analyzed at a single-cell level, using flow cytometry.

RESULTS

In the CD34+ APBSCT group, not only the absolute count of CD4+ T cells but also the proportion of Th1 cells in CD4+ T cells and the ratio of Th1 to Th2 after transplantation were significantly decreased at 2 and 4 weeks after transplantation compared with findings in the unselected APBSCT group.

DISCUSSION

We suggest that higher rates of infectious complications after CD34+ APBSCT may be due to the inability of residual T cells from the CD34+ cell selection to generate mature T cells that function adequately against infection. Although further study would be required, our preliminary data provide some information on the immune reconstitution after CD34+ APBSCT and differentiation of T lymphocytes into Th1 and Th2 in vivo.

The dose of infused lymphocytes in the autograft directly correlates with clinical outcome after autologous peripheral blood hematopoietic stem cell transplantation in multiple myeloma

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in multiple myeloma (MM); however, factors affecting ALC-15 in MM remain unknown. We hypothesized that the dose of infused peripheral blood autograft lymphocytes (autograft absolute lymphocyte count: A-ALC) impacts ALC-15 recovery. Between 1989 and 2001, 267 consecutive MM patients underwent APHSCT. We set out to determine the correlation between A-ALC and ALC-15 and the utility of A-ALC as a marker for ALC-15 recovery. A-ALC was found to be both a strong predictor for area under curve (AUC=0.93; P=0.0001) and strongly correlated with (r(s)=0.83; P=0.0001) ALC-15 recovery. Higher infused A-ALC was significantly correlated with an ALC-15>/=500/microl. In addition, median post-transplant overall survival (OS) and time to progression (TTP) were longer in patients who received an A-ALC>/=0.5 x 10(9) lymphocytes/kg versus A-ALC <0.5 x 10(9) lymphocytes/kg (58 vs 30 months, P=0.00022; 22 vs 15 months, P<0.00012, respectively). Multivariate analysis demonstrated A-ALC as an independent prognostic indicator for OS and TTP. These results indicate that an infused dose of autograft lymphocytes significantly impacts clinical outcome post-APHSCT in MM.

Hemopoietic Recovery and Infectious Complications in Breast Cancer and Multiple Myeloma after Autologous CD34+ Cell-Selected Peripheral Blood Progenitor Cell Transplantation

Autografting with CD34+ cell-selected peripheral blood progenitor cells (PBPC) is often associated with a prolonged recovery time and a higher incidence of infections. The aim of our study was to evaluate whether underlying disease influences hemopoietic recovery and the infectious complications occurring after transplantation. We studied 19 breast cancer (BC) patients and 17 multiple myeloma (MM) patients entered in a high-dose chemotherapy (HDC) program of tandem autografting with CD34+ cell-selected PBPC. PBPC were collected after mobilizing chemotherapy plus granulocyte colony-stimulating factor and were processed for selection of CD34+ cells. After selection, a median of 53% CD34+ cells was recovered with a median final purity of 92% with no significant differences between the MM (52% and 92%, respectively) and BC (53% and 89%, respectively) patients. Medians of 4.5 x 10(6)/kg CD34+ cells (BC, 4.4 x 10(6)/kg; MM, 5.4 x 10(6)/kg) and 18 x 10(4)/kg colony-forming units-granulocyte-macrophage (BC, 21 x 10(4)/kg: MM, 16 x 10(4)/kg) were reinfused after each HDC. Twenty-six patients (10 MM and 16 BC) underwent tandem autografting, and 10 patients received only 1 autograft because of inadequate collection (5 patients), clinical condition (3 patients), and refusal (2 patients). In the BC patients, the HDC regimen included a high-dose melphalan course followed by an ICE (ifosfamide, carboplatin, and etoposide) course. In the MM patients, the regimen consisted of a course of high-dose melphalan therapy and a course of ICBV (idarubicin, cyclophosphamide [Cytoxan], BCNU, and etoposide) or total body irradiation, etoposide, and Cytoxan. We found a significantly prolonged time for neutrophil recovery to > 500/microL in the MM patients (13 days versus 10 days; P < .002), whereas the times for platelet recovery to > 20,000/microL in the two groups were not different (13 days versus 12 days; not significant). No late engraftment failures and no toxic deaths were observed. The incidences of extrahematologic toxicity were similar for the two patient groups. All patients received similar anti-infection prophylaxis for 3 months after transplantation. After 12 months of observation, we found a statistically significant higher incidence of bacterial infections in MM patients in both the early (77.8% versus 48.6%; P < .034) and the late (41.1% versus 0%; P < .014) posttransplantation periods, whereas the incidences of fungal infections were similar in the two groups. Viral infections consisted of herpes zoster virus infection in 2 patients of each group, and cytomegalovirus infection was observed in 3 MM patients and no BC patients. Our experience demonstrates a prolonged neutrophil recovery time and higher incidences of bacterial and viral infections in MM patients compared with BC patients. These observations, although limited by the small sample size, suggest that the underlying disease may influence the incidence of infections after CD34- cell-selected transplantation and should be considered in the planning of appropriate antimicrobial prophylaxis in the autologous transplantation setting.

Efficacy of granulocyte transfusions for neutropenia-related infections: retrospective analysis of predictive factors

BACKGROUND

The transfusion of G-CSf-primed granulocytes (GTX) might represent an important treatment option for neutropenia-related infections unresponsive to conventional antimicrobial therapies and to recombinant hematopoietic growth factors. However, few studies to date have identified the factors that can predict clinical outcome and the patient populations who are likely to benefit most from GTX. The primary endpoint of the present retrospective study was to evaluate the efficacy of GTX in 22 patients with hematological malignancies who developed neutropenia-related bacterial and fungal infections that were unresponsive to appropriate antimicrobial therapies.

METHODS

Peripheral blood granulocytes were collected by continuous-flow leukapheresis from HLA-identical siblings after priming with G-CSF. The response to GTX was classified as 'favorable' if clinical symptoms and signs of infection resolved or 'unfavorable' if clinical symptoms and signs of infection were unchanged or worsened. Control of infection at Day 30 after the enrollment in the GTX program was considered as the outcome variable in multiple regression analysis.

RESULTS

Two patients died of infection before receiving the granulocyte concentrates. Bacterial infections (monomicrobial or mixed bacteremias) were documented in 11 patients, whereas fungal infections (fungemia or focal fungal infections) were diagnosed in seven patients. In two patients, no infecting agent could be isolated (clinical infection). Control of infection at Day 30 after the first GTX was achieved in 10 of 20 assemble patients. Overall, 54% of patients with bacterial infections had a favorable response, compared with 57% of patients with fungal infections. No differences in terms of survival were found when comparing patients with bacterial and those with fungal infections at a median follow-up 90 days from the first GTX. In univariate analysis, disease status before GTX, e.g., complete or partial remission, and spontaneous recovery of the neutrophil count were significantly associated with control of infection. when multivariate regression models were formed, the recovery 0.5 x 10 (9)/L PMN was the only parameter that significantly and independently correlated with a favorable response to GTX.

DISCUSSION

GTX can be used to successfully treat bacterial as well as fungal infections in severely neutropenic patients when administered early after the onset of febrile neutropenia in patients with remission of the underlying disease and who are likely to recover marrow function.

Adoptive transfer of costimulated T cells induces lymphocytosis in patients with relapsed/refractory non-Hodgkin lymphoma following CD34+-selected hematopoietic cell transplantation

We explored the feasibility and toxicity of administering escalating doses of anti-CD3/CD28 ex vivo costimulated T cells as a therapeutic adjunct for patients with relapsed, refractory, or chemotherapy-resistant, aggressive non-Hodgkin lymphoma (NHL) following high-dose chemotherapy and CD34+-selected hematopoietic cell transplantation (HCT). Sixteen patients had infusions on day 14 after HCT of autologous T cells that had been stimulated using beads coated with anti-CD3 and anti-CD28 monoclonal antibodies. At baseline, the subjects had severe quantitative and functional T-cell impairments. The culture procedure partially reversed impaired cytokine responsiveness in T cells in vitro and in vivo. Transient dose-dependent infusion toxicities were observed. There was a rapid reconstitution of lymphocytes; however, there were persistent defects in CD4 T cells. Most interestingly, 5 patients had a delayed lymphocytosis between day 30 and day 120 after HCT. Maximal clinical responses included 5 patients with a complete response (CR), 7 patients with a partial response (PR), and 4 patients with stable disease. At a median follow-up of 33 months (range, 26-60 months), 5 patients are alive with stable or relapsed disease and 3 patients remain in CR. In conclusion, this phase 1 trial demonstrates that adoptive transfer of autologous costimulated T cells (1) is feasible in heavily pretreated patients with advanced NHL, (2) is associated with a rapid recovery of lymphocyte counts, (3) reverses cytokine activation deficits in vitro, and (4) is associated with delayed lymphocytosis in a subset of patients.

Identification of a novel subpopulation of human cord blood CD34-CD133-CD7-CD45+lineage- cells capable of lymphoid/NK cell differentiation after in vitro exposure to IL-15

The hemopoietic stem cell (HSC) compartment encompasses cell subsets with heterogeneous proliferative and developmental potential. Numerous CD34(-) cell subsets that might reside at an earlier stage of differentiation than CD34(+) HSCs have been described and characterized within human umbilical cord blood (UCB). We identified a novel subpopulation of CD34(-)CD133(-)CD7(-)CD45(dim)lineage (lin)(-) HSCs contained within human UCB that were endowed with low but measurable extended long-term culture-initiating cell activity. Exposure of CD34(-)CD133(-)CD7(-)CD45(dim)lin(-) HSCs to stem cell factor preserved cell viability and was associated with the following: 1) concordant expression of the stem cell-associated Ags CD34 and CD133, 2) generation of CFU-granulocyte-macrophage, burst-forming unit erythroid, and megakaryocytic aggregates, 3) significant extended long-term culture-initiating cell activity, and 4) up-regulation of mRNA signals for myeloperoxidase. At variance with CD34(+)lin(-) cells, CD34(-)CD133(-)CD7(-)CD45(dim)lin(-) HSCs maintained with IL-15, but not with IL-2 or IL-7, proliferated vigorously and differentiated into a homogeneous population of CD7(+)CD45(bright)CD25(+)CD44(+) lymphoid progenitors with high expression of the T cell-associated transcription factor GATA-3. Although they harbored nonclonally rearranged TCRgamma genes, IL-15-primed CD34(-)CD133(-)CD7(-)CD45(dim)lin(-) HSCs failed to achieve full maturation, as manifested in their CD3(-)TCRalphabeta(-)gammadelta(-) phenotype. Conversely, culture on stromal cells supplemented with IL-15 was associated with the acquisition of phenotypic and functional features of NK cells. Collectively, CD34(-)CD133(-)CD7(-)CD45(dim)lin(-) HSCs from human UCB displayed an exquisite sensitivity to IL-15 and differentiated into lymphoid/NK cells. Whether the transplantation of CD34(-)lin(-) HSCs possessing T/NK cell differentiation potential may impact on immunological reconstitution and control of minimal residual disease after HSC transplantation for autoimmune or malignant diseases remains to be determined.

Hematopoietic stem cell graft manipulation as a mechanism of immunotherapy

Hematopoietic stem cell transplants (SCT) are used in the treatment of neoplastic diseases, in addition to congenital, autoimmune, and inflammatory disorders. Both autologous and allogeneic SCT are used, depending on donor availability and the type of disease being treated, resulting in different morbidity and outcomes. In both types of SCT, immune regulation via graft manipulation is being studied, although with highly different targeted outcomes. In general, autologous SCT have lower treatment-related morbidity and mortality, but a higher incidence of tumor relapse, and graft manipulation targets immune augmentation and/or the reduction of immune tolerance. In contrast, allogeneic SCT have a higher incidence of treatment-related morbidity and mortality and a significantly longer time of disease progression, and the targeted outcomes or graft manipulation focus on a reduction in graft versus host disease (GVHD). One source of the increased relapse rate and shorter overall survival (OS) following high dose chemotherapy (HDT) and autologous SCT is the immune tolerance that limits host response, both innate and antigen (Ag) specific, against the tumor. The immune tolerance that is observed is due in part to the tumor burden and prior cytotoxic therapy. Therefore, graft manipulation, as an adjuvant therapeutic approach in autologous SCT, is primarily focused on non-specific or specific immune augmentation using cytokines and vaccines. Recently, manipulation of the infused product as a form of cellular therapy has begun to also focus on approaches to reduce immune tolerance found in transplant patients, both prior to and following HDT and SCT. To this end, graft manipulation to reduce the presence of Fas Ligand (FasL)-expressing cells or interleukin (IL)10 and tumor growth factor (TGF)beta production has been proposed. In contrast to autologous transplantation, graft manipulation during allogeneic transplantation is used extensively. This includes limiting the infusion of T cells within the product or as a donor leukocyte infusion (DLI), resulting in a reduction in GVHD and the induction of long-term survivors. Indeed, allogeneic SCT provide the only curative therapy for patients with chronic myelogenous leukemia (CML), refractory acute leukemia, and myelodysplasia. The curative potential of allogeneic SCT is reduced, however, by the development of GVHD, a potentially lethal T-cell-mediated immune response targeting host tissues [Int. Arch. Allergy Immunol. 102 (1993) 309, J. Exp. Med. 183 (1996) 589]. The morbidity and mortality associated with GVHD limit this technology, resulting focus on those patients who have no alternative therapeutic options or who have advanced disease. Thus, allogeneic SCT provide one of the few statistically supported demonstrations of therapeutic efficacy by T cells (comparison of allogeneic to autologous transplantation). In contrast to autologous transplantation, control of GVHD following allogeneic SCT focuses on immune suppression and the induction of tolerance. Here too, graft manipulation is appropriate, and there are numerous studies of T-cell depletion to reduce GVHD, with or without the isolation and infusion of T cells as DLI. Additional strategies are examining the isolation and infusion of T cells with graft versus leukemia (GVL) activity to reduce GVHD and/or the infusion of genetically manipulated and/or selected cellular populations (monocytes or dendritic cells (DC)) to induce tolerance. Therefore, depending upon the type of transplant, the goals associated with graft manipulation can be radically different. In this review, we emphasize using graft manipulation to regulate immune tolerance and anergy in association with SCT. Although this paper focuses on hematopoietic SCT, it should be noted that these strategies are relevant to conditions other than neoplastic and congenital diseases, including solid organ transplants, and autoimmune and inflammatory diseases.

Re-infused autologous graft natural killer cells correlates with absolute lymphocyte count recovery after autologous stem cell transplantation

Early absolute lymphocyte count (ALC) has been reported to be a powerful prognostic indicator of survival after autologous stem cell transplantation (ASCT). One possible source affecting ALC recovery includes the re-infused autologous graft lymphocytes (AGL). To assess if the re-infused AGL correlate with ALC recovery post-ASCT, we conducted a pilot study to identify which of the re-infused AGL subsets is most associated with day 15 ALC recovery in three patients with multiple myeloma and four patients with non-Hodgkin's lymphoma. Using the Spearman rank correlation coefficient analysis (r), we compared absolute numbers of CD3, CD4, CD8, CD19, and CD16+/CD56+ cells/kg of body weight from the apheresis product with ALC (cells/microl) at day 15 post-ASCT. The main lymphocyte subsets identified in the apheresis product were T cells and NK cells. There was no strong correlation between T or B cells from the apheresis product compared with the ALC at day 15 post-ASCT (CD3, r = 0.21; CD4, r = 0.32; CD8, r = 0.39; and CD19, r = 0.14). However, there was good correlation between NK cells from the apheresis product compared with ALC at day 15 post-ASCT (CD16+/CD56+/CD3-, r = 0.77). These data provide preliminary evidence that the number of re-infused autologous graft NK cells in the apheresis product significantly affect ALC recovery early post-ASCT. However, given the small sample size, our results are primarily hypothesis generating and subject of further research.

Cellular and humoral immune reconstitution after autologous peripheral blood stem cell transplantation (PBSCT)

Immune reconstitution after autologous peripheral blood stem cell transplantation (PBSCT) is of particular interest because of its importance for clinical outcome. Despite prolonged immunosuppression, especially of CD4(+) cells, few infections after neutrophil recovery occur. Only reactivation of varicella zoster virus (VZV) is more frequent in the first year after transplantation. From August 1997 to May 2001, we prospectively evaluated 38 patients prior to conditioning and during follow-up of 12 months post-transplant for virus antibodies [measles, mumps, rubella, polio, herpes simplex, varicella zoster, mononucleosis, cytomegalovirus (CMV)] and lymphocyte subpopulations by flow cytometry. CD3(+) T lymphocytes, CD8(+) T cells, and B-lymphocyte reconstitution in our study confirms previous reports. Complete CD4(+) lymphocyte reconstitution was not achieved in the 12 months post-transplant leading to a suppressed CD4/CD8 ratio. IgG antibody titers against measles, mumps, rubella, and polio were present in almost all patients pretransplant and during 12 months post-transplant, indicating persistent humoral immunity. CD3(+) and CD8(+) counts of patients with clinical VZV reactivation ( n=5) post-transplant were significantly higher (median: 1201/microl and 938/microl, respectively) than in patients without VZV reactivation (median: 594/microl and 482/microl, respectively) 6-12 months post-transplant. Positive CMV titers pretransplant ( n=19) were also correlated with higher CD3(+) and CD8(+) counts 3-6 months post-transplant (median: 1050/microl and 1056/microl, respectively) compared to CMV-negative patients (738/microl and 584/microl, respectively), although none of the patients suffered from CMV disease. Therefore, we conclude that persistent viral infections can contribute to the CD8(+) T-cell reconstitution after PBSCT by oligoclonal expansion of antigen-specific memory CD8(+) T cells.

Evidence for naive T-cell repopulation despite thymus irradiation after autologous transplantation in adults with multiple myeloma: role of ex vivo CD34+ selection and age

Immunodeficiency following autologous CD34+-purified peripheral blood stem cell (PBSC) transplantation could be related to T-cell depletion of the graft or impaired T-cell reconstitution due to thymus irradiation. Aiming to assess the role of irradiated thymus in T-cell repopulation, we studied 32 adults with multiple myeloma, randomly assigned to receive high-dose therapy including total body irradiation (TBI) followed by autologous transplantation with either unselected or CD34+-selected PBSCs. The median number of reinfused CD3+ cells was lower in the selected group (0.03 versus 14 x 10(6)/kg; P =.002). Lymphocyte subset counts were evaluated from month 3 to 24 after grafting. Naive CD4+ T cells were characterized both by phenotype and by quantification of T-cell receptor rearrangement excision circles (TRECs). The reconstitution of CD3+ and CD4+ T cells was significantly delayed in the CD34+-selected group, but eventually led to counts similar to those found in the unselected group after month 12. Mechanism of reconstitution differed, however, between both groups. Indeed, a marked increase in the naive CD62L+CD45RA+CD4+ subset was observed in the selected group, but not in the unselected group in which half of the CD45RA+CD4+ T cells appear to be CD62L-. Age was identified as an independent adverse factor for CD4+ and CD62L+CD45RA+CD4+ T-cell reconstitution. Our results provide evidence that infusing PBSCs depleted of T cells after TBI in adults delays T-cell reconstitution but accelerates thymic regeneration.

Rapid immune reconstitution following autologous hematopoietic stem cell transplantation in children: a single institution experience

In this retrospective study, we review the immune reconstitution of children undergoing autologous hematopoietic stem cell transplantation. A total of 125 patients underwent autologous transplantation between 1992 and 2000. The report includes data on 58 patients. Data were not available on the remaining patients who either died before testing or data were not obtained. The parameters evaluated include: (a) immunophenotype by flow cytometry to quantify lymphocyte subpopulations (b) mitogen stimulation assays, and (c) quantitative immunoglobulins. The analysis reveals that CD3+ cells did not reach the normal range during the first year post-transplant. The median percentage of CD4+ cells was below normal up to 6 months post-transplant, while the absolute number remain low throughout the first year. The CD8+ percentage and absolute numbers remain normal at all times post-transplant. The CD19+ cells were also normal post-transplantation. The mitogen lymphocyte stimulation was normal in 27 out of 31 patients tested after 6 months post-transplant. Our analysis of immune reconstitution shows a similar pattern to previous studies with a faster recovery of the CD4/CD8 ratio, especially in those patients who did not receive TBI. In conclusion, the observed deficiencies are transient and have very little clinical significance because, historically, the rate of serious infections is low despite prolonged immune suppression. The recovery post-autologous transplant is fast.

Heterologous cells cooperate to augment stem cell migration, homing, and engraftment

T-lymphocyte depletion of bone marrow grafts compromises engraftment, suggesting a facilitating mechanism provided by the T cells that has been shown to associate with CD8(+) but not CD4(+) T cells. Explanations for this phenomenon have focused on immune targeting of residual host cells or cytokine production. We provide evidence for an alternative mechanism based on cooperative effects on cell motility. We observed that engraftment of CD34(+) cells in a beta(2)-microglobulin-deficient nonobese diabetic/severe combined immunodeficiency (beta(2)m(-/-) NOD/SCID) mouse model paralleled clinical observations in humans, with an enhancing effect noted from the addition of CD8(+) cells but not CD4(+) cells. This correlated with CD8(+) augmentation of CD34(+) cell homing to the bone marrow in vivo and CD8(+) cell-associated increases of CD34(+) cell transmigration through a bone marrow endothelial cell line in vitro. The cooperative interaction was not sensitive to brefeldin A inhibition of protein secretion. However, cytochalasin D-induced inhibition of CD8(+) cytoskeletal rearrangements abrogated CD34(+) transendothelial migration and impaired CD34(+) cell homing in vivo. CD8(+) cells did not migrate in tandem with CD34(+) cells or alter endothelial barrier integrity; rather, they affected phosphotyrosine-mediated signaling in CD34(+) cells in response to the chemokine stromal derived factor-1alpha (SDF-1alpha). These data demonstrate cell-cell cooperativity between different cell types in mediating chemotactic events and provide one potential explanation for the clinically observed effect of CD8(+) cells on bone marrow transplantation. This modification of cell migration by neighboring cells provides broad possibilities for combinatorial effects between cells of different types to influence cell localization.

Immune reconstitution following hematopoietic stem-cell transplantation

BACKGROUND

Reconstitution of the immune system following allogeneic stem-cell transplantation is a complex process that requires successful engraftment of the hematopoietic stem cell, as well as adequate thymic function. As the majority of patients have reduced thymic function due to age, hormonal changes, as well as the damage caused by conditioning and GvHD, immune recovery is often delayed and incomplete. Following graft infusion there is rapid proliferation of natural killer (NK) cells that appear to proceed directly from the hematopoietic stem cell. B-cell function is dependent on specific maturation development in the BM micro-environment, as well as CD4 help. The CD8 population expands rapidly due to proliferation of many memory cells that react against Class I Ags, as well as viral molecules. Expansion of T-helper cells originates mainly from the memory pool that is present in the bone marrow graft. Naive cells require competent thymus hence the CD4 cell counts may be subnormal with clinical immunodeficiency. Controversy remains as to the capacity of the thymus to recover and thus extra thymic proliferation of T cells have been postulated. However these cells appear to have a limited capacity to expand and a fixed repertoire.

DISCUSSION

Donor lymphocyte infusions may contribute a competent CD4 population that can cause GvHD, but have limitations in the capacity to respond to new antigens. Future research needs to be concentrated on improving the capacity of the thymus to reconstitute a functional naive population.

Impact of high-dose chemotherapy on antigen-specific T cell immunity in breast cancer patients. Application of new flow cytometric method

The present study analyses the influence of high-dose chemotherapy (HD) and autologous stem cell transplantation on natural and vaccine-induced specific immunity in breast cancer patients. Peripheral blood was collected from five breast cancer patients at serial time points in connection with treatment and in a follow-up period of 1 year. The frequencies of CD8+ and CD4+ T cells responsive to cytomegalovirus (CMV), varicella zoster virus (VZV), and tetanus in antigen-activated whole blood were determined by flow cytometric analysis of CD69, TNF alpha, IFN gamma and IL-4 expression. Mononuclear cells were labelled with PKH26 dye and the CMV, VZV, and tetanus toxoid-specific proliferation of T cell subpopulations was analysed by flow cytometry. In none of the patients did the treatment result in loss of overall T cell reactivity for any of the antigens. Prior to chemotherapy 5/5 patients possessed TNF alpha expressing T cells specific for CMV, 4/5 for VZV, and 3/5 for tetanus. One year after stem cell transplantation all patients possessed TNF alpha expressing T cells specific for CMV, VZV and tetanus. The highest percentages of cytokine-responding T cells were seen after stimulation with CMV antigen. In general, the lowest reactivity (close to zero) was measured in G-CSF-mobilised blood at the time of leukapheresis. In spite of a continuously reduced CD4 to CD8 ratio after transplantation, recovery of CD4+ T cells usually occurred prior to CD8+ recovery and often to a higher level. The study demonstrates that natural as well as vaccine-induced specific immunity established prior to HD can be regained after stem cell transplantation. These data indicate that introduction of a preventive cancer vaccination in combination with intensive chemotherapy may be a realistic treatment option.

Immune reconstitution after autologous peripheral blood progenitor cell transplantation: effect of interleukin-15 on T-cell survival and effector functions

OBJECTIVE

The aim of this study was to evaluate the occurrence of T-cell spontaneous apoptosis (A(spont)) and its modulation in vitro by the interleukin-2 receptor (IL-2R) gamma-chain (gammac)-signaling cytokine IL-15 in patients transplanted with autologous peripheral blood progenitor cells (PBPC) for hematologic malignancies.

MATERIALS AND METHODS

Patients were examined on days 30-60, 60-90, and 90-120 after PBPC infusion. Dissipation of mitochondrial transmembrane potential, a hallmark of T-cell apoptosis, has been detected using the fluorescent probe 3,3'-dihexyloxacarbocyanine iodide, after short-term T-cell culture in the absence or presence of exogenous cytokines. Expression of Bcl-2 family members has been studied by flow cytometry and reverse transcriptase polymerase chain reaction. T-cell proliferative responses to recall antigens have been estimated in autologous mixed leukocyte cultures.

RESULTS

A(spont) was seen in 45% +/- 6% of CD4(+) and 55% +/- 6% of CD8(+) T cells cultured in the absence of cytokines. Of interest, IL-15 and, to a lesser extent, its structural cousin IL-2 counteracted T-cell A(spont) by inhibiting the processing of caspase-3 and up-regulating Bcl-2 mRNA and protein levels. Cell division tracking confirmed that IL-15 did not rescue T cells from A(spont) by promoting proliferation but rather acted as a genuine survival factor. Addition of a gammac-blocking antibody to cytokine-conditioned cultures abrogated both apoptosis inhibition and Bcl-2 induction by IL-15, suggesting involvement of the IL-2Rgammac signal transduction pathway. Whereas cytokine-unprimed posttransplant T cells mounted inadequate responses to recall antigens, T cells conditioned with IL-15 expanded vigorously, indicating restoration of antigen-specific proliferation.

CONCLUSIONS

T cells recovering after autologous PBPC transplantation are highly susceptible to spontaneous apoptosis in vitro. This phenomenon can be counteracted by the gammac-signaling cytokine IL-15. These findings suggest that IL-15 might be a promising immunomodulating agent to improve postgrafting T-cell function.

The role of growth factor administration and T-cell recovery after peripheral blood progenitor cell transplantation in the treatment of solid tumors: results from a randomized comparison of G-CSF and GM-CSF

BACKGROUND

Peripheral blood progenitor cell (PBPC) transplantation (PBPCT) combined with post-PBPCT administration of myelopoietic growth factors is a valid therapeutic intervention to rapidly restore hematopoiesis after the delivery of intensive, myeloablative cancer chemotherapy. On the other hand, the best growth factor regimen to potentiate PBPC-mediated immunohematopoietic recovery has yet to be determined.

STUDY DESIGN AND METHODS

In a randomized evaluation, the effects produced by post-PBPCT G-CSF and GM-CSF on myeloid/lymphoid recovery and transplant outcome in women with chemosensitive cancer were compared. Thirty-seven ovarian cancer patients and 34 breast cancer patients ranging in age from 24 to 60 years were treated with carboplatin, etoposide, and melphalan (CEM) high-dose chemotherapy and then randomly assigned to receive G-CSF (5 microg/kg subcutaneously) or GM-CSF (5 microg/kg subcutaneously) until Day 13 after PBPCT. Patients were compared in regard to hematopoietic recovery, posttransplant clinical management, and immune recovery. Finally, clinical outcome was estimated as time to progression and overall survival.

RESULTS

Hematopoietic recovery and posttransplant clinical management were comparable in both the G-CSF and GM-CSF series. Conversely, significantly higher T-cell counts were observed in G-CSF-treated patients during the early and late posttransplant follow-up. Patients who received G-CSF showed a significantly longer median time to progression. A parallel analysis revealed that patients in whom a higher CD3+ count was recovered had a significantly longer overall survival and time to progression.

CONCLUSION

The enhancement of post-PBPCT T-cell recovery observed in G-CSF-treated patients encourages the use of G-CSF to ameliorate immune recovery, which seems to play a role in post-PBPCT control of disease in cancer patients. GM-CSF might be administered to prolong immunosuppression after autologous PBPCT for autoimmune diseases or allogeneic PBPCT.

Immune reconstitution after autologous selected peripheral blood progenitor cell transplantation: comparison of two CD34+ cell-selection systems

BACKGROUND

Selection of CD34+ PBPCs has been applied as a method of reducing graft contamination from neoplastic cells. This procedure seems to delay lymphocyte recovery, while myeloid engraftment is no different from that with unselected PBPC transplants.

STUDY DESIGN AND METHODS

Lymphocyte recovery was studied in two groups of patients who underwent autologous CD34+ PBPC transplant with two different technologies (Ceprate SC, Cellpro [n = 17]; CliniMACS, Miltenyi Biotech [n = 13]). The median number of CD34+ cells transfused was 3.88 x 10(6) per kg and 3.32 x 10(6) per kg, respectively. Residual CD3 cells x 10(6) per kg were 4.97 and 0.58, respectively (p = 0.041). Residual CD19 cells x 10(6) per kg were 1.33 and 0.73, respectively (NS).

RESULTS

No differences were found between the two groups in total lymphocyte recovery to >0.5 x 10(9) per L, which achieved a stable count by Day 30. During the study period, the CD4+ cell count remained below 0.2 x 10(9) per L, and the B-cell subset showed a trend toward normalization. CD3/HLA-DR+ and CD16/56 increased markedly in both groups by Day 30. An increase in CMV (13%) and adenovirus (17.4%) infection was found in both groups.

CONCLUSION

Both CD34+ cell selection technologies used here determined an excellent CD34+ cell purity and an optimal depletion of T cells. The high rate of viral complications is probably due to the inability of residual T cells left from the CD34+ cell selection to generate, immediately after transplant, an adequate number of virus-specific lymphocytes.

Interim analysis of the use of the anti-idiotype breast cancer vaccine 11D10 (TriAb) in conjunction with autologous stem cell transplantation in patients with metastatic breast cancer

The anti-idiotype monoclonal antibody breast cancer vaccine 11D10 (TriAb) was administered before and after autologous stem cell transplantation (ASCT) in 45 patients with metastatic breast cancer whose disease was responsive to conventional chemotherapy. Evidence of a positive anti-anti-idiotype antibody (Ab3) humoral response was noted at a median of 1.76 months post-ASCT (range, before ASCT-6 months) with this strategy. Maximal Ab3 levels and idiotype-specific T-cell proliferative responses were observed at a median of 3 and 4 months, respectively, after ASCT. The achievement of rapid immune responses after ASCT, during a known period of decreased immunoresponsiveness, opens the possibility of an additional antitumor effect at a time when the tumor burden is relatively small. Moreover, in this interim analysis, patients with the most vigorous humoral and cellular immune responses had a significant improvement in progression-free survival. Further follow-up and evaluation of this approach is warranted.