Phenotypic analysis of functional T-lymphocyte subtypes and natural killer cells in human cord blood: relevance to umbilical cord blood transplantation

From cord to caudate: characterizing umbilical cord blood stem cells and their paracrine interactions with the injured brain

Stem cells are proving to be a promising therapy for a wide range of pediatric disorders, from neonatal hypoxic-ischemic encephalopathy to pediatric leukemia. Owing to their low immunogenicity and ease of availability, umbilical cord blood (UCB) progenitor cells are increasingly replacing fetal- and adult-derived cells in therapeutic settings. Multiple environmental and demographic factors affect the number and type of stem cells extracted from UCB, and these differences have been associated with disparities in outcomes after transplantation. To avoid variations in efficacy, as well as the potential adverse effects of stem cell transplantation, evaluation of the stem cell secretome is critical to identify key paracrine signals released by the stem cells that could be used to provide similar neuroprotective effects to stem cell transplantation. This article describes the cell types found in UCB and reviews the available literature surrounding the effects of collection timing and volume, maternal risk factors, delivery characteristics, and neonatal demographics on the cellular composition of UCB. In addition, the current findings regarding the stem cell secretome are discussed to identify factors that could be used to supplement or replace stem cell transplantation in pediatric neuroprotection.

Efficacy and safety of combined immunosuppressive therapy plus umbilical cord blood infusion in severe aplastic anemia patients: A cohort study

The present study aimed to evaluate the efficacy and safety of combined immunosuppressive therapy (IST) plus umbilical cord blood infusion (UCBI) in severe aplastic anemia (SAA) patients. A total of 68 patients with SAA were enrolled in the current prospective cohort study and divided into the IST (n=35; positive control) and IST+UCBI (n=33; experimental) groups according to the treatment conditions. Patients in the IST group were treated with rabbit antithymocyte globulin (r-ATG) at a dose of 2.5 mg/kg through intravenous infusion once a day for five days. This was combined with oral cyclosporine A (CsA) at a dose of 3–5 mg/kg twice a day for 2 years. Patients in the IST+UBCI group were treated with r-ATG and CsA at the same doses and frequencies as the IST group plus one UCBI 1 day after the final treatment with r-ATG. At 6 months post treatment, the complete response and overall response rate (ORR) of the IST+UCBI group were markedly higher compared with those in the IST group. Furthermore, patients in the IST+UCBI group achieved absolute neutrophil count (ANC) and platelet count responses more rapidly as compared with the IST group. However, no difference in the hemoglobin (Hb) response was identified between the two groups. In addition, SAA patients achieved responses in the ANC and platelet count more rapidly in comparison with very severe aplastic anemia (VSAA) patients, while the number of days to Hb responses were similar in the SAA and VSAA patients. Multivariate logistic regression analysis also revealed that IST+UCBI treatment was an independent predicting factor for patients achieving complete response or partial response, whereas VSAA was an independent predictor of a worse ORR. Platelet and reticulocyte were also independent predicting factors. Finally, the survival of patients was similar between the groups, and no difference in the safety of the treatment was observed. In conclusion, combined IST plus UCBI treatment may be applied as an effective and safe therapy for SAA patients.

Stem cells to restore insulin production and cure diabetes

BACKGROUND

The advancement of knowledge in the field of regenerative medicine is increasing the therapeutic expectations of patients and clinicians on cell therapy approaches. Within these, stem cell therapies are often evoked as a possible therapeutic option for diabetes, already ongoing or possible in the near future.

AIM

The purpose of this document is to make a point of the situation on existing knowledge and therapies with stem cells to treat patients with diabetes by focusing on some of the aspects that most frequently raise curiosity and discussion in clinical practice and in the interaction with the patient. In fact, at present there are no clinically approved treatments based on the use of stem cells for the treatment of diabetes, but several therapeutic approaches have already been evaluated or are being evaluated in clinical trials.

DATA SYNTHESIS

It is possible to identify three large potential application fields: 1) the reconstruction of the β cell mass; 2) the immunomodulation in type 1 diabetes (T1D); 3) the treatment of complications. In this study we will limit the discussion to approaches that have the potential for clinical translation, deliberately omitting aspects of basic biology and preclinical data. Also, we intentionally omit the treatment of the complications that will be the subject of a future document. Finally, an overview of the Italian situation regarding the storage of cord blood cells for the therapy of diabetes will be given.

Cellular engineering and therapy in combination with cord blood allografting in pediatric recipients

Cord blood (CB) transplantation is an alternate source of human hematopoietic progenitor cells for allogeneic stem cell transplantation in children and adolescents with both malignant and nonmalignant diseases. Current limitations included delay in hematopoietic reconstitution, increased incidence of primary graft failure and slow cellular immunoreconstitution. These limitations lead to a significant increase in primary graft failure, infectious complications and increased transplant-related mortality. There is a number of experimental approaches currently under investigation including cellular engineering to circumvent these limitations. In this review, we summarize the recent findings of utilizing ex vivo CB expansion with Notch1 ligand Delta 1, mesenchymal progenitor cells, the use of human placenta-derived stem cells and CB-derived natural killer cells. Early and preliminary results suggest some of these experimental cellular strategies may in part ameliorate the incidence of primary graft failure, delays in hematopoietic reconstitution and/or slowness in cellular immune reconstitution following unrelated CB transplantation.

The potential of cytotherapeutics in hematologic reconstitution and in the treatment and prophylaxis of graft-versus-host disease. Chapter I: current practice and remaining unmet medical needs

Hematopoietic stem cell transplantation is a life-saving treatment for inherited anemias, immunodeficiencies or hematologic malignancies. When using partially HLA-matched allografts, a major complication is graft-versus-host disease (GvHD). The ideal attributes of a transformational new GvHD treatment include improved survival, decreased corticosteroids, decreased antifungals, improved quality of life through decreased infections, reduced number of hospital stay days, reduced risks of developing chronic GvHD impact on lower GI tract and liver, prophylactic benefits and decreased GvHD relapses, but, in the case of cancer, without negatively impacting beneficial graft-versus-tumor effects. The current practice of hematopoietic stem cell transplantation, its incidence and its unmet medical needs are reviewed here and discussed.

T-lymphocyte recovery and function after cord blood transplantation

The Szabolcs laboratory is focused on understanding the biology of donor-derived cellular immunity in recipients of allogeneic hematopoietic cell transplantation that can be translated into new immunotherapy strategies. To this end, we are focused on developing novel laboratory approaches to analyze and augment immune recovery for high risk patient cohorts without increasing graft-versus-host disease. Much of our work has focused on unrelated cord blood transplantation as the dominant clinical scenario and laboratory model. Our overarching goal is to minimize transplant-related mortality and morbidity and render HLA-mismatched unrelated cord blood transplant, a widely accepted safe cellular therapy. Donor leukocyte infusions in the allogeneic hematopoietic transplant setting can provide a clinically relevant boost of immunity to reduce opportunistic infections and to increase graft-versus-leukemia activity. Our laboratory has a major focus toward ex vivo expansion of cord blood T cells with anti-apoptotic cytokines and CD3/CD28 co-stimulatory beads. Expanded lymphocytes lack alloreactivity against recipient and other allogeneic cells indicating a favorable safety profile from graft-versus-host disease. Nevertheless, expanded T cells can be primed subsequently against lymphoid and myeloid leukemia cells to generate tumor-specific cytotoxic T cells. These findings offer a major step in fulfilling critical biological requirements to quickly generate a cellular product ex vivo, using a negligible fraction of a cord blood graft that provides a flexible adoptive immunotherapy platform for both children and adults.

Activated T cells from umbilical cord blood armed with anti-CD3 × anti-CD20 bispecific antibody mediate specific cytotoxicity against CD20+ targets with minimal allogeneic reactivity: a strategy for providing antitumor effects after cord blood transplants

BACKGROUND

In this study, we asked whether anti-CD3-activated T cells (ATCs) from cord blood (CB) could be expanded and targeted to solid tumors or hematologic malignancies for infusions after unrelated CB stem cell transplant and whether cord blood ATCs (CBATCs) could reduce alloresponsiveness.

STUDY DESIGN AND METHODS

CB mononuclear cells (MNCs) were activated with anti-CD3 (20 ng/mL) and expanded for 14 days in interleukin-2 (100 IU/mL). CBATCs were armed with anti-CD3 × anti-CD20 (CD20Bi) or anti-CD3 × anti-Her2 (Her2Bi) bispecific antibodies (CBaATCs) and tested for specific cytotoxicity, cytokine secretion, and alloresponsiveness.

RESULTS

Our results show the mean expansion of CBATCs to be 37-fold after 14 days of culture from either frozen (n=4) or fresh (n=4) CB units. Cytotoxicity was optimal when CBATCs were armed with 50 ng of CD20Bi/10(6) cells. Cytotoxicity peaked between Day 8 and Day 10 for both bispecific antibodies. At an effector-to-target ratio of 25:1, the mean cytotoxicities of CBATCs armed with Her2Bi or CD20Bi were 40% (n=4) and 30% (n=4), respectively. CBaATCs exhibited peak specific interferon-γ enzyme-linked immunosorbent spots on Day 10. CBATCs and CBaATCs suppressed responsiveness to alloantigens by 20% to 50% when compared with normal allogeneic peripheral blood MNC response.

CONCLUSION

We showed that armed CBATCs mediate specific cytotoxicity, secrete low levels of cytokines and chemokines, and demonstrate attenuated response to alloantigens.

Dendritic cells in cord blood transplantation: a review

Dendritic cells (DCs) are a heterogeneous population of antigen-presenting cells derived from hematopoietic progenitors that bridge the transition between the innate and adaptive immune responses, while maintaining self-tolerance and Th1/Th2 homeostasis, by priming other cells in either an immunogenic or tolerogenic direction. Through their role in both innate and adaptive immunity, DCs play a major part in transplant engraftment and rejection and in graft-versus-host disease (GvHD). Preferentially tolerogenic or immunogenic DC subtypes offer targets for immunotherapy, to optimize transplant success rates and prolong disease-free and overall survival. Cord blood DCs are immature and preferentially tolerogenic, due to maternal-fetal tolerance, leading to better graft acceptance and immune reconstitution and explaining the lower incidence and severity of GvHD in CB transplantation, despite donor-host mismatching. Manipulation of DC maturation and cell loading with tumor-antigens can direct antitumor immunity and target minimal residual disease, as demonstrated for acute myeloid leukemia, optimizing the graft-versus-leukemia effect.

T lymphocytes derived from human cord blood provide effective antitumor immunotherapy against a human tumor

Background

Although the graft-versus-tumor (GVT) effect of donor-derived T cells after allogeneic hematopoietic stem cell transplantation has been used as an effective adoptive immunotherapy, the antitumor effects of cord blood (CB) transplantation have not been well studied.

Methods

We established the animal model by transplantation of CB mononuclear cells and/or tumor cells into NOD/SCID mice. The presence of CB derived T cells in NOD/SCID mice or tumor tissues were determined by flow cytometric and immunohistochemical analysis. The anti-tumor effects of CB derived T cells against tumor was determined by tumor size and weight, and by the cytotoxicity assay and ELISPOT assay of T cells.

Results

We found dramatic tumor remission following transfer of CB mononuclear cells into NOD/SCID mice with human cervical tumors with a high infiltration of CD3⁺ T cells in tumors. NOD/SCID mice that receive neonatal CB transplants have reconstituted T cells with significant antitumor effects against human cervical and lung tumors, with a high infiltration of CD3⁺ T cells showing dramatic induction of apoptotic cell death. We also confirmed that T cells showed tumor specific antigen cytotoxicity in vitro. In adoptive transfer of CD3⁺ T cells into mice with pre-established tumors, we observed much higher antitumor effects of HPV-specific T cells by ELISPOT assays.

Conclusions

Our results show that CB derived T lymphocytes will be useful for novel immunotherapeutic candidate cells for therapy of several tumors in clinic.

Umbilical cord blood: biology and transplantation

Umbilical cord blood transplantation is becoming an acceptable alternative source of hematopoietic stem cells for patients with malignant diseases. Cord blood differs from bone marrow and peripheral blood progenitors in its immune tolerance and kinetics of engraftment. In this article, we will review the biology of cord blood stem cells and clinical studies of cord blood transplants in pediatric and adult populations. We will also discuss potential uses of cord blood stem cells in regenerative medicine and novel methods for ex vivo expansion of hematopoietic stem cells. As we learn more about cord blood transplants, there is the potential to overcome the limitations of cord blood transplants so that they can become more widely available.

The immunobiology of cord blood transplantation

Despite significant recent advances in the applicability and outcome following unrelated cord blood transplantation (UCBT), infections remain a major cause of mortality associated with poor immune recovery in the first 6 months after UCBT. Enhanced immune reconstitution not only could improve survival by reduced transplant related mortality, but may also favorably impact on relapse incidence by improved graft-versus-leukemia effects. This review will summarize our current understanding of the biology of immune recovery post-UCBT with an emphasis on adaptive T cell dependent immunity. New efforts to boost immunity will be also highlighted including our own laboratory, where ex vivo T cell expansion is pursued towards adoptive immunotherapy.

The potential utility of bone marrow or umbilical cord blood transplantation for the treatment of type I diabetes mellitus

The pathology of type 1 diabetes mellitus (T1D) involves the autoimmune destruction or malfunction of pancreatic β cells, leading to a lack of insulin. The absence of insulin is life-threatening, necessitating daily hormone injections from an exogenous source. Insulin injections do not adequately mimic the precise regulation of β cells on glucose homeostasis, however, eventually leading to complications in diabetic patients. There currently is no definitive cure for T1D. Pancreas transplantation, although quite successful, is an invasive intervention that is restricted to patients with advanced complications, requires constant immunosuppression, and is severely limited by donor availability. Recent progress in human islet cell isolation and immunosuppressive protocols has restored euglycemia in patients who received islet cells from 2 or 3 pancreas donors. However, because of the scarcity of cadaver pancreata and the low yield of islet cells obtained by the procedure, not all patients have access to this surgical intervention. Thus, other therapeutic approaches are needed to arrest immune aggression, preserve β cell mass, and provide efficient replacement. In this sense, bone marrow and umbilical cord blood transplantation are promising possibilities that merit exploration. In this review, we summarize multiple strategies that have been proposed and tested for potential therapeutic benefit in patients with T1D.

The effect of IL-28A on human cord blood CD4+ T cells

BACKGROUND AND AIM

The utilization of umbilical cord blood transplantation (UCBT) has been increasing because of the potential advantage of rapid accessibility and the lesser risk of graft-versus-host disease (GVHD), thus allowing less strict HLA matching. IL-28A, also known as IFN-lambda2, has been regarded as a member of a new cytokine family that shares some features with type I interferon (IFN) and was shown to have antiviral activity. The aim of this study was to identify biological activity of IL-28 on cord blood CD4(+) T cells.

MATERIALS AND METHODS

In this study, we cultured CD4(+) T cells with IL-28A (20 ng/ml), IL-2 (20 ng/ml) and 5microg/ml MACS Anti-Biotin MACSiBead Particles (bead-to-cell ratio 1:2) for 2 weeks.

RESULTS

Flow cytometry analyses showed that IL-28A cannot be effective on CD25 and Foxp3 expression on cord blood CD4(+) T cells, and it is not involved in proliferation of these cells. Treg suppression assay also showed that this cytokine cannot induce production of regulatory T cells.

CONCLUSION

We showed that IL-28A is not involved in expression of CD25 and Foxp3 markers and proliferation of CD4(+)CD25(-) T cells, and that our findings also suggest that induction of Foxp3 in T cells activated by anti-CD3/anti-CD28 does not result in the regulatory activity in these cells.

Stem cell therapy for type 1 diabetes mellitus

The use of stem cells in regenerative medicine holds great promise for the cure of many diseases, including type 1 diabetes mellitus (T1DM). Any potential stem-cell-based cure for T1DM should address the need for beta-cell replacement, as well as control of the autoimmune response to cells which express insulin. The ex vivo generation of beta cells suitable for transplantation to reconstitute a functional beta-cell mass has used pluripotent cells from diverse sources, as well as organ-specific facultative progenitor cells from the liver and the pancreas. The most effective protocols to date have produced cells that express insulin and have molecular characteristics that closely resemble bona fide insulin-secreting cells; however, these cells are often unresponsive to glucose, a characteristic that should be addressed in future protocols. The use of mesenchymal stromal cells or umbilical cord blood to modulate the immune response is already in clinical trials; however, definitive results are still pending. This Review focuses on current strategies to obtain cells which express insulin from different progenitor sources and highlights the main pathways and genes involved, as well as the different approaches for the modulation of the immune response in patients with T1DM.

Allogeneic haematopoietic stem cell transplantation: individualized stem cell and immune therapy of cancer

The year 2009 marked the fiftieth anniversary of the first successful allogeneic haematopoietic stem cell transplant (HSCT). The field of HSCT has pioneered some of the most exciting areas of research today. HSCT was the original stem cell therapy, the first cancer immune therapy and the earliest example of individualized cancer therapy. In this Timeline article we review the history of the development of HSCT and major advances made in the past 50 years. We highlight accomplishments made by researchers who continue to strive to improve outcomes for patients and increase the availability of this potentially life-saving therapy for patients with otherwise incurable malignancies.

Clearance of CMV viremia and survival after double umbilical cord blood transplantation in adults depends on reconstitution of thymopoiesis

Umbilical cord blood grafts are increasingly used as sources of hematopoietic stem cells in adults. Data regarding the outcome of this approach in adults are consistent with delayed and insufficient immune reconstitution resulting in high infection-related morbidity and mortality. Using cytomegalovirus (CMV)-specific immunity as a paradigm, we evaluated the status, mechanism, and clinical implications of immune reconstitution in adults with hematologic malignancies undergoing unrelated double unit cord blood transplantation. Our data indicate that CD8(+) T cells capable of secreting interferon-gamma (IFN-gamma) in a CMV-specific enzyme-linked immunosorbent spot (ELISpot) assay are detectable at 8 weeks after transplantation, before reconstitution of thymopoiesis, but fail to clear CMV viremia. Clearance of CMV viremia occurs later and depends on the recovery of CD4(+)CD45RA(+) T cells, reconstitution of thymopoiesis, and attainment of T-cell receptor rearrangement excision circle (TREC) levels of 2000 or more copies/mug DNA. In addition, overall survival was significantly higher in patients who displayed thymic regeneration and attainment of TREC levels of 2000 or more copies/mug DNA (P = .005). These results indicate that reconstitution of thymopoiesis is critical for long-term clinical outcome in adult recipients of umbilical cord blood transplant. The trial was prospectively registered at http://www.clinicaltrials.gov (NCT00133367).

Autologous umbilical cord blood transfusion in very young children with type 1 diabetes

OBJECTIVE

Interest continues to grow regarding the therapeutic potential for umbilical cord blood therapies to modulate autoimmune disease. We conducted an open-label phase I study using autologous umbilical cord blood infusion to ameliorate type 1 diabetes.

RESEARCH DESIGN AND METHODS

Fifteen patients diagnosed with type 1 diabetes and for whom autologous umbilical cord blood was stored underwent a single intravenous infusion of autologous cells and completed 1 year of postinfusion follow-up. Intensive insulin regimens were used to optimize glycemic control. Metabolic and immunologic assessments were performed before infusion and at established time periods thereafter.

RESULTS

Median (interquartile range [IQR]) age at infusion was 5.25 (3.1-7.3) years, with a median postdiagnosis time to infusion of 17.7 (10.9-26.5) weeks. No infusion-related adverse events were observed. Metabolic indexes 1 year postinfusion were peak C-peptide median 0.50 ng/ml (IQR 0.26-1.30), P = 0.002; A1C 7.0% (IQR 6.5-7.7), P = 0.97; and insulin dose 0.67 units * kg(-1) * day(-1) (IQR 0.55-0.77), P = 0.009. One year postinfusion, no changes were observed in autoantibody titers, regulatory T-cell numbers, CD4-to-CD8 ratio, or other T-cell phenotypes.

CONCLUSIONS

Autologous umbilical cord blood transfusion in children with type 1 diabetes is safe but has yet to demonstrate efficacy in preserving C-peptide. Larger randomized studies as well as 2-year postinfusion follow-up of this cohort are needed to determine whether autologous cord blood-based approaches can be used to slow the decline of endogenous insulin production in children with type 1 diabetes.

Immune reconstitution in children after unrelated cord blood transplantation

There is a great need to learn more about the biology of immune recovery after UCBT. Fundamental gaps in knowledge remain regarding the biology and kinetics of developing antigen-specific protective immunity and understanding the impact of recipient age and immunosuppressive agents. However, there is also realistic hope that clinical translation of new immunotherapy strategies could enhance immune competence after UCBT either by having an impact on the thymic-independent early period or by fostering thymic recovery.

Chemotactic mediators of Th1 T-cell trafficking in smokers and COPD patients

Chronic obstructive pulmonary disease (COPD) is smoking-related and associated with increased cytotoxic CD8+ T-cells in the airway. There is a wide range of susceptibility to the damaging effects of cigarette smoke with only a small proportion of smokers progressing to COPD. We have previously reported increased intracellular Th1 cytokines in blood, BAL and intraepithelial CD8+T cells in current and ex-smokers with COPD, whereas healthy smokers showed localized Th1 response in the lung only. We thus hypothesised that Th1-associated chemokines or their receptors on CD8+T-cells may be differentially expressed in the blood of healthy smokers, current smoker COPD subjects and those who had ceased smoking. We investigated chemokines, chemokine receptors and Th1 and cytotoxic T-cell markers in blood and BAL using flow cytometry, ELISA and cytometric bead array. In blood, CXCR3, CCR4, intracellular CCR3 and the Th1 marker 62L(-)CD45RO(+) were increased in both COPD groups and healthy smokers. In contrast, cytotoxic T-cells, ITAC, MIG, IFN-gamma and CCR5 were increased in both COPD groups but not smokers. In BAL, the Th1 marker 62L(-)CD45RO(+), CCR5, CXCR3, IFN-gamma, RANTES, IL-8, MCP-1, MIG and ITAC were increased in both COPD groups and smokers versus controls. Our findings are consistent with systemic inflammation in COPD associated with an increased influx of cytotoxic and Th1 cells into the airway. The differential expression of specific chemokines and their receptors in blood from COPD subjects and healthy smokers suggests that inclusion of these markers in any panel designed for the non-invasive investigation of smokers with a disposition to COPD would be clinically relevant.

The contribution of hematopoietic stem cells to beta-cell replacement

Hemopoietic stem cells (HSCs) are commonly used for curing malignant and nonmalignant hematopoiesis disorders. In recent years, HSC potential giving rise to multilineage progeny has been reported. This issue, together with their availability and number, has made them ideal candidates for beta-cell replacement in diabetic patients. HSC capacity to differentiate to insulin-producing cells has been at the center of debate for the past 5 years and it now seems that their role could more likely be that of helper cells able to facilitate survival or stimulate proliferation of endogenous beta cells. In addition, clinical studies are ongoing about the possible use of HSCs to stop autoimmune destruction at the onset of diabetes or to induce tolerance through microchimerism in pancreatic islet transplantation.

Umbilical cord blood T cells express multiple natural cytotoxicity receptors after IL-15 stimulation, but only NKp30 is functional

The natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46 are thought to be NK lineage restricted. Herein we show that IL-15 induces NCR expression on umbilical cord blood (UCB) T cells. NCRs were mainly on CD8(+) and CD56(+) UCB T cells. Only NKp30 was functional as demonstrated by degranulation, IFN-gamma release, redirected killing, and apoptosis. Since NCRs require adaptor proteins for function, the expressions of these adaptors were determined. The adaptors used by NKp30 and NKp46, FcepsilonR1gamma and CD3zeta, were detected in UCB T cells. There was a near absence of DAP12, the adaptor for NKp44, consistent with a hypofunctional state. NKp46 was on significantly fewer UCB T cells, possibly accounting for its lack of function. Adult peripheral blood (PB) T cells showed minimal NCR acquisition after culture with IL-15. Since UCB contains a high frequency of naive T cells, purified naive T cells from adult PB were tested. Although NKp30 was expressed on a small fraction of naive PB T cells, it was nonfunctional. In contrast to UCB, PB T cells lacked FcepsilonR1gamma expression. These results demonstrate differences between UCB and PB T cells regarding NCR expression and function. Such findings challenge the concept that NCRs are NK cell specific.

Umbilical cord blood T cells express multiple natural cytotoxicity receptors after IL-15 stimulation, but only NKp30 is functional

The natural cytotoxicity receptors (NCRs) NKp30, NKp44, and NKp46 are thought to be NK lineage restricted. Herein we show that IL-15 induces NCR expression on umbilical cord blood (UCB) T cells. NCRs were mainly on CD8(+) and CD56(+) UCB T cells. Only NKp30 was functional as demonstrated by degranulation, IFN-gamma release, redirected killing, and apoptosis. Since NCRs require adaptor proteins for function, the expressions of these adaptors were determined. The adaptors used by NKp30 and NKp46, FcepsilonR1gamma and CD3zeta, were detected in UCB T cells. There was a near absence of DAP12, the adaptor for NKp44, consistent with a hypofunctional state. NKp46 was on significantly fewer UCB T cells, possibly accounting for its lack of function. Adult peripheral blood (PB) T cells showed minimal NCR acquisition after culture with IL-15. Since UCB contains a high frequency of naive T cells, purified naive T cells from adult PB were tested. Although NKp30 was expressed on a small fraction of naive PB T cells, it was nonfunctional. In contrast to UCB, PB T cells lacked FcepsilonR1gamma expression. These results demonstrate differences between UCB and PB T cells regarding NCR expression and function. Such findings challenge the concept that NCRs are NK cell specific.

Autologous umbilical cord blood infusion for type 1 diabetes

OBJECTIVE

The physical, emotional, and economic costs of type 1 diabetes (T1D) mandate continued efforts to develop effective strategies to prevent or reverse the disease. Herein, we describe the scientific and therapeutic rationale underlying efforts utilizing umbilical cord blood (UCB) as a therapy for ameliorating the progression of this autoimmune disease.

MATERIALS AND METHODS

We recently embarked on a pilot study to document the safety and potential efficacy of autologous UCB infusion in subjects with T1D. Under this protocol, patients recently diagnosed with the disease and for whom autologous cord blood is stored, undergo infusion. Studies are performed before infusion and every 3 to 6 months postinfusion for immunologic and metabolic assessment. To date, 15 autologous infusions have been performed.

RESULTS

Preliminary observations suggest that autologous cord blood transfusion is safe and provides some slowing of the loss of endogenous insulin production in children with T1D. Mechanistic studies demonstrate that umbilical cord blood contains highly functional populations of regulatory T cells (Treg) and that increased Treg populations may be found in the peripheral blood of subjects more than 6 months after cord blood infusion. We provide the rationale for cord blood-based therapies, a summary of our initial protocol, and plans for future studies designed to explore the potential of cord blood-derived regulatory T cells to treat T1D.

CONCLUSIONS

Prolonged follow-up and additional mechanistic efforts are urgently needed to determine if umbilical cord blood-derived stem cells can be used as part of safe and effective therapies for T1D.

Hyperacute graft-vs.-host disease after related HLA-identical umbilical cord blood transplantation

haGVHD has been described following bone marrow and peripheral blood stem cell transplantation and in a single case who received unrelated HLA mismatched CB. An unusual case of haGVHD following HLA 6/6-matched sibling CBT in a child with AML is presented. The development of haGVHD in a fully matched CBT and without precipitating factors may suggest the role of still undefined and perhaps individual contributory factors.

Immune reconstitution after unrelated cord blood transplantation

Over the past years unrelated cord blood transplant (UCBT) has emerged as an effective alternative to unrelated donor blood and marrow transplantation. However, despite several advantages, its success is limited by the high incidence of opportunistic infections (OI), most of which are viral. Infection-related mortality is the primary cause of death after UCBT with most deaths occurring in the first 3-6 months post transplant. For several months, until recovery of the thymus is restored to support de novo T cell generation, protective antiviral immunity depends on the activity of post-thymic T cells infused within the cord blood (CB) grafts. However, almost all CB T cells are antigen inexperienced (naïve) lymphocytes that have been functionally altered by placental factors to protect pregnancy. CB T cells need to undergo in vivo priming, Th1/Tc1 maturation, and peripheral expansion before they can afford immunologic protection. This article provides an overview of what is currently known regarding the reconstitution of adaptive immunity following UCBT including our own data from prospective analyses of pediatric cohorts. Remarkable immunophenotypic changes are notable already in the first 2-3 weeks post-UCBT. These changes result from apparent 'homeostatic' peripheral T cell expansion in the lymphopenic environment. While we can identify patient- and graft-specific predictive factors, the concordant emergence of T cell subsets displaying the phenotype of Th1/Tc1 cytotoxic effector cells can be statistically linked to those UCBT recipients who will subsequently develop viral and other opportunistic infections. Antigen presenting dendritic cell reconstitution may also reflect alterations in immunocompetence due to OI and/or GVHD.

Smoking alters alveolar macrophage recognition and phagocytic ability: implications in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is associated with defective efferocytosis (apoptosis and alveolar macrophage [AM] phagocytic function) that may lead to secondary necrosis and tissue damage. We investigated ex vivo AM phagocytic ability and recognition molecules (CD36, integrin alphaVbeta3, CD31, CD91, CD44) using flow cytometry. The transferrin receptor (CD71) was measured as an indicator of monocyte-macrophage differentiation in bronchoalveolar lavage (BAL). Proliferation was assessed with Ki-67. Based on evidence of systemic involvement in COPD, blood from 17 current smokers and 25 ex-smokers with COPD, 22 healthy smokers, and 20 never-smoking control subjects was also investigated. BAL was collected from 10 to 16 subjects in each group. Levels of recognition molecules and cAMP were assessed after exposure of AM to cigarette smoke in vitro. The phagocytic ability of AM was significantly decreased in both COPD groups and in healthy smokers compared with control subjects. However, phagocytic capacity was better in subjects with COPD who had ceased smoking, compared with those who were still smoking. AM from current smokers with COPD and healthy smokers exhibited reduced CD31, CD91, CD44, and CD71, and enhanced Ki-67 compared with healthy never-smoker control subjects. There were no differences in these markers in AM from ex-smokers with COPD compared with control subjects, or in blood monocytes from any group. Suppressive effects of cigarette smoke on AM recognition molecules associated with an increase in cAMP were confirmed in vitro. Our data indicates that a smoking-related reduction in AM phagocytic ability and expression of several important recognition molecules may be at least partially normalized in those subjects with COPD who have ceased smoking.

Human umbilical cord blood progenitor cells are attracted to infarcted myocardium and significantly reduce myocardial infarction size

We are investigating the effects of human umbilical cord blood mononuclear progenitor cells (HUCBC) for the treatment of acute myocardial infarction because human cord blood is a readily available and an abundant source of primitive cells that may be beneficial in myocardial repair. However, there is currently no scientific consensus on precisely when to inject stem/progenitor cells for the optimal treatment of acute myocardial infarction. We used an in vitro assay to determine the attraction of infarcted rat myocardium at 1, 2, 2.5, 3, 6, 12, 24, 48, and 96 h after left anterior descending coronary artery (LAD) occlusion from 45 rats for HUCBC in order to determine the optimal time to transplant HUCBC after myocardial infarction. Our assay is based on the migration of fluorescent DAPI-labeled HUCBC from wells in an upper chamber of a modified Boyden apparatus through a semiporous polycarbonate membrane into wells in a lower chamber that contain either normal or infarcted myocardium. DAPI-labeled HUCBC (100,000) were placed in each of the separate wells above the membrane that corresponded to normal or infarct homogenate in the lower wells. The greatest HUCBC migration to infarcted myocardium occurred at 2 h and 24 h after LAD occlusion in comparison with normal controls. A total of 76,331 +/- 3384 HUCBC migrated to infarcted myocardium at 2 h and 69,911 +/- 2732 at 24 h after LAD occlusion (both p < 0.001) and significantly exceeded HUCBC migration to normal heart homogenate. The HUCBC migration remained greatest at 2 and 24 h after LAD occlusion when the number of migrated cells was adjusted for the size of each myocardial infarction. Injection of 106 HUCBC in saline into infarcted myocardium of non immunosuppressed rats within 2 h (n=10) or at 24 h (n=5) after LAD occlusion resulted in infarction sizes 1 month later of 6.4 +/- 0.01% and 8.4 +/- 0.02% of the total left ventricular muscle area, respectively, in comparison with infarction sizes of 24.5 +/- 0.02% (n=10) in infarcted rat hearts treated with only saline (p < 0.005). Acute myocardial infarction in rats treated with only saline increased the myocardial concentration of tumor necrosis factor-alpha (TNF-alpha) from 6.9 +/- 0.8% to 51.3 +/- 4.6%, monocyte/macrophage chemoattractant protein (MCP-1) from 10.5 +/- 1.1% to 39.2 +/- 2.0%, monocyte inflammatory protein (MIP) from 10.6 +/- 1.6% to 23.1 +/- 1.5%, and interferon-gamma (INF-gamma) from 8.9 +/- 0.3% to 25.0 +/- 1.7% between 2 and 12 h after coronary occlusion in comparison with known controls (all p < 0.001). In contrast, the myocardial concentrations of these cytokines in rat hearts treated with HUCBC did not significantly change from the controls at 2, 6, 12, and 24 h after coronary occlusion. The present investigations suggest that infarcted myocardium significantly attracts HUCBC, that HUCBC can substantially reduce myocardial infarction size, and that HUCBC can limit the expression of TNF-alpha, MCP-1, MIP, and INF-gamma in acutely infarcted myocardium.

Defective antigen-presenting cell function in human neonates

Immaturity of the immune system has been suggested as an underlying factor for the high rate of morbidity and mortality from infections in newborns. Functional impairment of neonatal T cells is frequently quoted as the main underlying mechanism for such immaturity. However, recent studies suggest that neonatal antigen-presenting cells (APCs) also exhibit functional alterations, which could lead to secondary defects of adaptive T-cell responses. In this review, we summarize what is known on the functionality of APC at birth and during early childhood. Compared to adults, neonatal APCs display markers of immaturity and produce low levels of cytokines. Multiple factors could be involved in neonatal APC alteration, such as intrinsic immaturity, defective interaction between APCs and T cells and regulatory T-cell-mediated inhibition. Characterization of the relative contribution of each mechanism is clearly needed to better understand the functional capability of the neonatal immune system.

Phenotypic changes associated with advancing gestation in maternal and fetal baboon lymphocytes

Baboons are very similar to humans in ontogeny, reproductive physiology, and placentation, and thus serve as an excellent nonhuman primate model for use in both normative and perturbation studies of pregnancy that cannot be performed on pregnant women. However, little is known about the changes induced by normal pregnancy in the maternal and fetal baboon in lymphocyte subset composition, and lymphocyte activation and proliferation. We performed multicolor flow cytometry analysis of peripheral venous blood samples obtained from pregnant baboons at mid-gestation (0.5 G), and from matched fetal heart (FH) and umbilical cord (UC) blood at the end of gestation (0.95 G). Compared with their mothers at 0.95 G, fetal lymphocytes had higher percentages of B and CD4+ T cells, and lower numbers of NK and CD8+ T cells. When comparing pregnant baboons at 0.5 and 0.95 G, we also found that pregnancy induces immune stimulation, measured as higher activation without proliferation of CD8+ T and NK cells in the maternal circulation. Our study adds new data to support the notion of pregnancy-induced immune activation and strengthens the value of the baboon as a nonhuman primate model for studies pertinent to human reproductive physiology, pathology, and vaccination.

Flow cytometric characterization of cell populations in bronchoalveolar lavage and bronchial brushings from patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a serious, chronic inflammatory disease of the airway associated with cigarette smoking. Leucocytes are involved in the inflammatory process in the airways in COPD. There is a need for accurate characterization of cellular populations in bronchoalveolar lavage (BAL) due to variation in the predominant cell types reported, which were investigated mostly with manual counting techniques.

METHODS

Bronchial brushings and BAL were obtained from human subjects undergoing fiber optic bronchoscopy. Flow cytometry was applied to identify various cell types. Quenching of autofluorescence of BAL-derived alveolar macrophages was achieved with eta-octyl beta-D-galactopyranoside and crystal violet. Comparisons of cell counts obtained with flow cytometric and manual counting methods were performed.

RESULTS

Correlation analysis showed that manual cell counting methods overestimated the percentage of macrophages when compared with flow cytometric methods (R2 = 0.54). There was also a small tendency by manual counting to underestimate the percentage of lymphocytes and neutrophils. Using flow cytometry, the percentage and absolute numbers of alveolar macrophages and lymphocytes in BAL were not significantly different between patients with COPD and control subjects. The percentage and absolute numbers of neutrophils were higher in BAL from patients with moderate to severe COPD.

CONCLUSIONS

This novel flow cytometric assay for identification of various cell types from heterogenous samples of BAL and bronchial brushing will allow further investigation of cell characteristics, such as cytokine production and receptor expression, and an accurate evaluation of apoptosis for different cell types and provide a rationale for urgently required effective treatments for COPD.

Cord blood transplantation in adult patients

Early clinical reports outlining outcomes for primarily pediatric patients undergoing UCB transplantation point to delayed time to hematopoietic recovery and favorable incidence and severity of GvHD. Recently, clinical reports in adult patients identified the feasibility of UCB transplantation for those patients lacking an available histocompatible-related or unrelated adult donor Intensive clinical and laboratory research is ongoing focused on strategies to foster UCB allogeneic donor engraftment thereby allowing wider application of this stem cell source for patients requiring allogeneic transplantation.

Hematopoietic stem cell transplantation using umbilical cord blood progenitors: review of current clinical results

SUMMARY

Umbilical cord blood (CB) has been rapidly established as an alternative source of stem cells to bone marrow for allogeneic-related and unrelated hematopoietic transplantation. To date, almost 70 000 CB units are available for transplantation and more than 2000 CB transplants (CBT) have been performed, mostly in children, for the treatment of a variety of malignant and nonmalignant conditions. Considerable experience has been rapidly accumulated in this field and many aspects of CBT have been elucidated, while other questions remain unresolved. A concise review of the clinical results achieved after related and unrelated CBT is presented and discussed.

Umbilical cord blood transplantation in adults using myeloablative and nonmyeloablative preparative regimens

Unrelated umbilical cord blood (UCB) transplantation has recently been explored in an increasing number of adult patients. The relative ease of procurement and the lower-than-anticipated risk of severe acute graft-versus-host disease has made UCB transplantation an appealing alternative to bone marrow-derived hematopoietic stem cells. The use of reduced-intensity or nonmyeloablative preparative regimens to allow engraftment of UCB broadens the scope of patients who may benefit from allogeneic immunotherapy, including elderly and medically infirm patients with no matched sibling donor. This review summarizes the available data on the use of UCB as an alternative source of hematopoietic stem cell transplantation in adult patients.

CD25+CD4+ T cells in human cord blood: an immunoregulatory subset with naive phenotype and specific expression of forkhead box p3 (Foxp3) gene

OBJECTIVE

To address the role of cord blood (CB) CD25+CD4+ T cells, the gene expressions and function of this subset were analyzed.

MATERIALS AND METHODS

CD25+CD4+ T cells fractionated from CB of term and preterm infants were subjected to flow cytometry, quantitative polymerase chain reaction analysis for cytokines, costimulatory molecules, and transcription factors, and functional assays.

RESULTS

Human preterm CB contained a high proportion of CD25+CD4+ T cells that declined with gestational age to the level of adult peripheral blood (PB). CD25+ or CD25-CD4+ T cells in CB had a higher frequency of CD45RA+ and CD38+ cells than in PB. CB CD25+CD4+ T cells less frequently expressed CD45RO, CD71, and HLA-DR than PB CD25+CD4+ T cells, despite similar expressions on CB and PB CD25-CD4+ T cells. No expression of IL-10, transforming growth factor-beta, interleukin-4, and interferon-gamma mRNA differed between CB CD25+CD4+ and CD25-CD4+ T cells, in contrast to the high interleukin-10 expression in PB CD25+CD4+ T cells. CTLA-4 was more transcribed in CB and PB CD25+CD4+ T cells than in the counterpart CD25-CD4+ T cells. CD28 or ICOS was similarly expressed in CB and PB T cells. CB CD25+CD4+ T cells effectively suppressed the proliferation of CB CD25-CD4+ T cells in a dose-dependent manner. Human CB and PB CD25+CD4+ T cells preferentially transcribed Foxp3, which governs the regulatory function of this subset in mice.

CONCLUSIONS

These results suggest that CB contains CD25+CD4+ regulatory T cells as a functionally mature population with naive phenotype. This subset may naturally arise and decline in fetus to play a potential immunoregulatory role in intrauterine life.

Immunophenotypic and Functional Characterization of Cord Blood Dendritic Cells

Dendritic cells (DCs) play a pivotal role in the activation of T cells, which are effector cells in graft-versus-host disease (GVHD). A low incidence of GVHD following cord blood (CB) transplantation has long been reported; despite this, little information is currently available on the characteristics of CB DCs. The goal of the present study was to investigate the immunophenotypic characteristics and distribution of CB DCs and their subsets. For that purpose we have analyzed 15 CB samples as compared to normal peripheral blood (PB) (n = 7) and blood from patients submitted to an allogeneic PB stem cell transplantation (allo-PBSCT) (n = 6). Our results show an overall decreased frequency of DCs in CB due to the presence of significantly lower numbers of CD123inter./CD33inter./CD16+ DCs. Phenotypically, CB DCs displayed a tendency to express lower levels of the gamma-chain interleukin-2 (IL-2) receptor (CD132) and of the CD86 co-stimulatory molecule, supporting a higher degree of immaturity for CB as compared to PB DCs. After activation of CB DCs with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) higher frequencies of cytokine-producing cells were found among CD123inter./CD33inter./CD16+ and CD123dim/CD33bright/CD16- DCs; however, when only the cytokine-producing DCs were considered, a significant decrease in the amount of different cytokine (e.g., IL-1beta and IL-6) produced per cell was observed especially for CD16+ CB DCs. These findings support a higher degree of immaturity for CB as compared to PB DCs that might contribute to explain, at least in part, the low incidence and severity of GVHD observed after CB transplantation.

Distinctive response of naïve lymphocytes from cord blood to primary activation via TCR

Umbilical cord blood (UCB) is now being considered an alternative to bone marrow for restoring hematopoiesis after myeloablative therapy. The lower risk of acute and chronic graft-versus-host disease in patients who received UCB cells seems related to the nature of UCB-T cells. Phenotypically, UCB-CD3+ cells are mostly naive (CD45RA+) and represent a transitional population between thymocytes and adult T cells. We examined the immune reactivity of highly purified, negatively selected CD4+CD45RA+ cells by mimicking activation via T cell receptor (TCR). All experiments included the extensively characterized adult peripheral blood (APB) cells as reference. On the contrary to APB, naive UCB-CD4+ cells were able to proliferate with anti-CD3 stimulation alone. With addition of interleukin (IL)-2 or costimulatory signal, both populations reached similar proliferation. Forty-eight hours after anti-CD3 stimulation, CD4+CD45RA+ from UCB, but not APB, showed characteristic blastic morphology and significant expression of CD25 on the surface. A low concentration of IL-2 was detected at 24 h by anti-CD3-stimulated UCB CD4+CD45RA+, which rapidly disappeared. By 72 h after activation, CD4+CD45RA+ UCB cells showed extensive apoptosis, whereas CD4+CD45RA+ APB cells showed low levels of apoptosis. Using RNase protection assay, we observed that CD95L levels were significantly higher in naive CD4+ cells from UCB than from APB after activation. However, neutralizing Fas-Fc protein was unable to inhibit anti-CD3-induced apoptosis, suggesting that this was a CD95-independent mechanism. These results indicate that UCB-CD4+CD45RA+ cells are able to start proliferating as a result of early IL-2 production after TCR engagement alone, but probably, as a result of the consumption of this IL-2, they undergo cell death.

Umbilical cord blood dendritic cells are a rich source of soluble HLA-DR: synergistic effect of exosomes and dendritic cells on autologous or allogeneic T-Cell proliferation

In this study, we compared soluble HLA-DR (sHLA-DR) production in the culture supernatants of various cell sources [T and B cells, monocytes and dendritic cells (DCs) either from adult peripheral blood (PB) or umbilical cord blood (UCB)]. DCs produced the highest amount of sHLA-DR molecules as compared to other cell sources, with UCB DCs producing the highest amount. Different kinetics of sHLA-DR production were found between immature and mature UCB DCs (mDC, iDC) (derived either from CD34(+) or CD14(+) cells). Maximum production of sHLA-DR was observed in 72-hour culture supernatants of both CD34- and CD14-derived mDCs, whereas it peaked in the 24-hour culture supernatants from iDC. sHLA-DR molecules were pelleted after sequential centrifugation from UCB CD34(+) DCs and were found to contain both 36 kD alpha-chain and 29 kD beta-chain of HLA-DR, CD86, and Fas molecules. These sHLA-DR containing vesicles/exosomes alone evoked weak proliferative responses from autologous and allogeneic T cells, but the immune response was significantly increased when vesicles/exosomes were presented with DCs.

Activated umbilical cord blood cells from pre-term and term neonates express CD69 and synthesize IL-2 but are unable to produce IFN-gamma

BACKGROUND

The immune response exhibits quantitative and qualitative differences throughout human development. Both phenotypical and functional immaturity of newborn immune cellular components have been reported. We aimed to analyze possible differences in cellular activation assessed by expression of surface CD69 and cytokine production in mononuclear peripheral blood cells from premature (<37) and term (>37 weeks of gestation) neonates compared to adult donors.

METHODS

Ten persons from each group were selected; none was infected, immunodepressed, under medical treatment, or had any congenital abnormalities. Blood was obtained from umbilical cord of term and pre-term donors and vein punction of adults. All samples were collected in heparin and subsequently activated with PHA-L or PMA plus ionomycin at 37 degrees C for 4 h. After incubation, cells were labeled to determine CD69 expression on CD3+CD4+, CD3+CD8+, CD19+, and CD16+56+ subpopulations. Intracellular staining was performed to analyze IFN-gamma, IL-2, and CD69 in CD3+ cells. After staining, cells were analyzed by flow cytometry.

RESULTS

We first found a substantially higher number of CD3+CD4+CD69+ cells in premature and term neonates than in adults. Secondly, percentage of CD3+CD8+, CD56+, and CD19+ cells expressing CD69 was similar among the three groups. Thirdly, expression of CD69 was higher in CD19+ cells than in CD16+56+ cells of all three groups. Regarding cytokine production, IFN-gamma was detected only in cells from adults and was consistent in all individuals analyzed. In sharp contrast, IL-2 and intracellular CD69 (iCD69) were detected in all three groups, with no significant differences among them. Induction of IL-2 and iCD69 showed that lack of response with IFN-gamma was restricted to pre-term and newborn populations.

CONCLUSIONS

In summary, our results showed that a) CD69 is an early activation marker of both mononuclear umbilical cord and peripheral blood cells activated by a mitogenic stimulus, and b) newborn CD3+ cells probably lack conditions required to progress through the activation process that leads to IFN-gamma production. These conditions are still unknown but certainly constitute an interesting issue for further studies.

T-Cell recovery in adults and children following umbilical cord blood transplantation

T-cell reconstitution following allogeneic stem cell transplantation may involve thymic education of donor-derived precursors or peripheral expansion of mature T cells transferred in the graft. T cell-receptor excision circles (sjTRECs) are generated within the thymus and identify new thymic emigrants and those that have not divided. We measured quantitative and qualitative immunologic reconstitution and sjTREC levels in adult and pediatric recipients of umbilical cord blood transplants (UCBTs). sjTRECs were detected at normal levels in all children, starting 12 months after transplantation. sjTRECs were not detected until 18 months after transplantation in adults, and then only at a 3-fold lower level than expected for age. We used complementarity-determining region 3 (CDR3) spectratyping to measure changes in T cell-receptor diversity occurring with restoration of thymic function. T-cell repertoires were skewed in adults and children at 12 to 18 months after transplantation but recovered to near-normal diversity at 2 to 3 years post-UCBT. T-cell repertoires appeared more diverse earlier in children (at 1 to 2 years post-UCBT) than in adults (at 3 to 4 years post-UCBT). We conclude that early T-cell recovery after UCBT occurs primarily through peripheral expansion of adoptively transferred donor T cells and results in skewing of the T-cell repertoire. The reappearance of sjTREC-containing cells after UCBT is associated with increasing numbers of phenotypicaly naive T cells, improved mitogen and recall antigen responses, and diversification of the T-cell repertoire. The delay in central T-cell recovery in adults relative to children may be due to differences in thymic function resulting from age-related atrophy, graft-versus-host disease, or the pharmacologic effects of prophylaxis and treatment of graft-versus-host disease.

Phenotypic and functional analysis of human T lymphocytes in early second- and third-trimester fetuses

This study was undertaken to investigate the phenotypic and functional status of T lymphocytes of human fetuses from early second- to third-trimester. Cord blood samples were obtained from 19 healthy human fetuses (gestation weeks: 18-36), by cordocentesis, and 16 term newborns (gestation weeks 37-42). Maternal and unrelated male blood samples were also taken as controls. Percentage of lymphocytes in fetal white blood cells was 79.3%, reducing to 40% by term birth, much higher than that of adults. Cord blood mononuclear cells (CBMC), prepared by density gradient centrifugation followed by lysis of erythrocytes, were stained using PE- or FITC-labelled monoclonal Abs and analysed by flow cytometry. The frequencies of CD3+ T cells in fetal (40.1%) and neonatal (42.4%) CBMC were significantly lower than that of men (59.6%) and pregnant women (53.6%). Proportions of CD8+ T cells (9.5%), gammadelta-T cells (0.5%) and NK cells (4.8%) in fetal CBMC were also lower than that of neonates (except gammadelta-T cells) and adults. A negative linear correlation (r = -0.609) between the ratio of CD4+/CD8+ T cells in fetal blood and gestation age could also be established. Fetal CBMC showed vigorous spontaneous proliferation but failed to respond to mitogen (PHA) or allogeneic stimulation in vitro. The fetal mononuclear cells were unable to produce IL-2, IL-4 or IFN-gamma, but spontaneously secreted IL-10, IL-6 and TNF-alphain vitro. Stimulation with PHA up-regulated the production of IL-10, IL-6 and TNF-alpha substantially.

Immunophenotypic profile of AC133-positive cells in bone marrow, mobilized peripheral blood and umbilical cord blood

AC133 is a molecule whose expression in the human hematopoietic system is restricted to a subset of CD34+ progenitor/stem cells with long-term repopulating ability. The antigenic features of these cells, like CD34+ cells, are described heterogeneous. The immunophenotypic profile of AC133+ cells, detected by means of dual-color flow cytometry, in bone marrow (BM), cytokine-mobilized peripheral blood (PB) and umbilical cord blood (UCB) was evaluated. The highest percentage of AC133+ cells was detected in mobilized PB despite not significantly different from that found in BM, but both are higher than that found in UCB. In addition, the highest percentage of CD34, HLA-DR and CD33 co-expressing AC133+ cells was observed in mobilized PB. Furthermore, UCB was found to be enriched in CD7+ and CD19+ cells and BM was found to be enriched in AC133+ cells co-expressing CDw90 and CD71. Our data confirm the immunophenotypic heterogeneity of cells expressing AC133 antigen, a promising new stem cell marker to be increasingly used as additional target for alternative identification and separation of early hematopoietic cells.