Assessing deviations for HPCs obtained during COVID-19 (ADHOC): Evaluating impact of the COVID-19 pandemic on cellular therapy products and processes, the BEST collaborative study

BACKGROUND

The success of allogeneic hematopoietic stem cell transplantation is dependent on a world-wide network of collection centers providing donations that predominantly have been infused as fresh cells. The logistics chain that supports the just-in-time delivery model for stem cell and immunotherapy products was severely stressed by the COVID pandemic, and in early 2020 a number of national and international bodies recommended that cells should be cryopreserved at the collection or transplant center to avoid interruptions in their acquisition or delivery to patients who had started conditioning.

STUDY DESIGN

To assess the potential consequences of such pandemic-related deviations to normal practice, we surveyed nine international laboratories to determine if the characteristics or transplant outcomes of allogeneic stem cell donations differed in the immediate periods before and after the switch to routine cryopreservation.

RESULTS

Nine centers on two continents provided data for 72 HSC donations just before, and 71 just after, switching to cryopreservation for allogeneic HSC products. No statistically significant differences between the period before and after cryopreservation were noted for time from product collection to receipt, product temperature at receipt, or CD34⁺ cell viability at receipt. There was an indication of slower absolute neutrophil count recovery after cryopreservation was required (mean time of 15 vs. 17.6 days).

DISCUSSION

While there were no apparent changes to most parameters studied, there was an indication of slower neutrophil engraftment that will need to be examined in larger, longer term studies.

Differential cytokine expression in direct and indirect co-culture of islets and mesenchymal stromal cells

BACKGROUND

Transplantation of allogenic Langerhans islets (ISL) has been employed as an alternative to pancreas transplantation to provide endogenous supply of insulin and treat hypoglycemia unawareness in type 1 diabetes. Nevertheless, the process of islets isolation exposes the islets to hypoxia and other aggressive conditions that results in the recover of less than half of the islets present in the pancreas. Several studies demonstrated that co-culturing islets with mesenchymal stromal cells (MSC) before implantation enhances islets survival and function and this effect is mediated by cytokines. However, it remains unclear if the profile of cytokines secreted by MSC in co-culture with islets changes upon the type of co-culture: direct and indirect.

MATERIALS AND METHODS

In 3 series of experiments with human islets of 3 different donors, we compared the levels of a panel of cytokines measured in the supernatant of ISL cultured alone, Wharton Jelly MSC (WJMSC) cultured alone, direct co-culture of ISL-WJMSC and indirect co-culture using a permeable transwell membrane to separate ISL and WJMSC.

RESULTS

Comparing the profile of cytokines secreted by islets alone with islets in direct co- culture with WJMSC, we found higher expression of IL1b, IL17, IFγ, IL4, IL10, IL13, Granulocyte-macrophage colony-stimulating factor (GMCSF) and Leptin, in the supernatant of the co-cultures. In contrast, when comparing islets cultured alone with islets in indirect co-culture with MSC, we found no significant differences in the levels of cytokines we analyzed.

CONCLUSION

Direct contact between human WJMSC and pancreatic islets is required for elevated expression of a range of immune cytokines, including both those considered inflammatory, and anti-inflammatory.

Immune reconstitution following umbilical cord blood transplantation: IRES, a study of UK paediatric patients

To obtain a qualitative as well as quantitative view immune reconstitution following umbilical cord blood (UCB) transplantation of paediatric patients, we utilised a broad panel of flow cytometry markers to monitor the phenotypes of lymphoid and myeloid cells at 1‐12 months post‐transplant. Samples were received from 46 patients with a median age of 3.3 years and survival was 76% at 1 year. Monocytes were at similar or higher median levels than in adult controls at all times tested, with a high CD16+ proportion in the first 3 months. NK cells were also within adult ranges, with a CD56++ high proportion in the first 6 months. B cell recovery was seen from 2 months in most patients and T cells from 3 months, both were delayed with anti‐thymocyte globulin (ATG) treatment. CD4:CD8 ratios were high in the first 6 months, and the proportion of T cells with recent thymic emigrant and naïve phenotypes rose from 3 months. NK and plasmacytoid dendritic cell numbers remained at reduced levels in patients not surviving to 1 year. Our results can serve as a useful reference for detailed monitoring of immune reconstitution in paediatric recipients of UCB.

Variations in novel cellular therapy products manufacturing

BACKGROUND AIMS

At the frontier of transfusion medicine and transplantation, the field of cellular therapy is emerging. Most novel cellular therapy products are produced under investigational protocols with no clear standardization across cell processing centers. Thus, the purpose of this study was to uncover any variations in manufacturing practices for similar cellular therapy products across different cell processing laboratories worldwide.

METHODS

An exploratory survey that was designed to identify variations in manufacturing practices in novel cellular therapy products was sent to cell processing laboratory directors worldwide. The questionnaire focused on the manufacturing life cycle of different cell therapies (i.e., collection, purification, in vitro expansion, freezing and storage, and thawing and washing), as well as the level of regulations followed to process each product type.

RESULTS

The majority of the centers processed hematopoietic progenitor cells (HPCs) from peripheral blood (n = 18), bone marrow (n = 16) or cord blood (n = 19), making HPCs the most commonly processed cells. The next most commonly produced cellular therapies were lymphocytes (n = 19) followed by mesenchymal stromal cells (n = 14), dendritic cells (n = 9) and natural killer (NK) cells (n = 9). A minority of centers (<5) processed pancreatic islet cells (n = 4), neural cells (n = 3) and induced-pluripotent stem cells (n = 3). Thirty-two laboratories processed products under an investigational status, for either phase I/II (n = 27) or phase III (n = 17) clinical trials. If purification methods were used, these varied for the type of product processed and by institution. Environmental monitoring methods also varied by product type and institution.

CONCLUSION

This exploratory survey shows a wide variation in cellular therapy manufacturing practices across different cell processing laboratories. A better understanding of the effect of these variations on the quality of these cell-based therapies will be important to assess for further process evaluation and development.

Current practices for viability testing of cryopreserved cord blood products: an international survey by the cellular therapy team of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative

BACKGROUND

Viability testing is a common practice in laboratories. The goal of this study was to ascertain current laboratory practices internationally for performing viability testing for cryopreserved cord blood (CB) products and glean information about how to standardize the method to improve interlaboratory reproducibility.

STUDY DESIGN AND METHODS

A survey to evaluate current laboratory practices for viability testing was designed and distributed internationally. The question topics included sampling and testing methods, responses to unexpected results, and the rating of the reliability of the CB quality tests, together with expectations for standardization.

RESULTS

There were 32 respondents to the survey, of whom 28 responded to the more detailed questionnaire about viability methods. Overall, responses indicated that various stains were used among the laboratories, and when multiple sites used the same viability stain the methods differed. The majority of the respondents were in favor of standardizing the viability testing methods. A wide variety of preferences were communicated about how to standardize the method, but a majority did advocate the use of 7-aminoactinomycin D (7-AAD) with flow cytometry.

CONCLUSIONS

The survey results revealed a variety of tests and inconsistent interlaboratory practices for performing the viability assay. Flow cytometry with a 7-AAD dye was suggested as a first step toward standardization.

Mesenchymal stromal cells as treatment or prophylaxis for acute or chronic graft-versus-host disease in haematopoietic stem cell transplant (HSCT) recipients with a haematological condition

BACKGROUND

Recipients of allogeneic haematopoietic stem cell transplants (HSCT) can develop acute or chronic, or both forms of graft-versus-host disease (a/cGvHD), whereby immune cells of the donor attack host tissues. Steroids are the primary treatment, but patients with severe, refractory disease have limited options and a poor prognosis. Mesenchymal stromal cells (MSCs) exhibit immunosuppressive properties and are being tested in clinical trials for their safety and efficacy in treating many immune-mediated disorders. GvHD is one of the first areas in which MSCs were clinically applied, and it is important that the accumulating evidence is systematically reviewed to assess whether their use is favoured.

OBJECTIVES

To determine the evidence for the safety and efficacy of MSCs for treating immune-mediated inflammation post-transplantation of haematopoietic stem cells.

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in the Cochrane Central Register of Controlled Trials (CENTRAL, the Cochrane Library 2018, Issue 12), MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1937), Web of Science: Conference Proceedings Citation Index-Science (CPCI-S) (from 1990) and ongoing trial databases to 6 December 2018. No constraints were placed on language or publication status.

SELECTION CRITERIA

We included RCTs of participants with a haematological condition who have undergone an HSCT as treatment for their condition and were randomised to MSCs (intervention arm) or no MSCs (comparator arm), to prevent or treat GvHD. We also included RCTs which compared different doses of MSCs or MSCs of different sources (e.g. bone marrow versus cord). We included MSCs co-transplanted with haematopoietic stem cells as well as MSCs administered post-transplantation of haematopoietic stem cells.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.We employed a random-effects model for all analyses due to expected clinical heterogeneity arising from differences in participant characteristics and interventions.

MAIN RESULTS

We identified 12 completed RCTs (879 participants), and 13 ongoing trials (1532 enrolled participants planned). Of 12 completed trials, 10 compared MSCs versus no MSCs and two compared different doses of MSCs. One trial was in people with thalassaemia major, the remaining trials were for haematological malignancies. Seven trials administered MSCs to prevent GvHD, whereas five trials gave MSCs to treat GvHD.In the comparison of MSCs with no MSCs, cells were administered at a dose of between 10⁵ and 10⁷ cells/kg in either a single dose (six trials) or in multiple doses (four trials) over a period of three days to four months. The dose-comparison trials compared 2 x 10⁶ cells/kg with 8 x 10⁶ cells/kg in two infusions, or 1 x 10⁶ cells/kg with 3 x 10⁶ cells/kg in a single infusion.The median duration of follow-up in seven trials which administered MSCs prophylactically ranged from 10 to 60 months. In three trials of MSCs as treatment for aGvHD, participants were followed up for 90 or 100 days. In two trials of MSCs as treatment for cGvHD, the mean duration of follow-up was 13.4 months (MSC group) and 23.6 months (control group) in one trial, and 56 weeks in the second trial. Five trials included adults only, six trials included adults and children, and one trial included children only. In eight trials which reported the gender distribution, the percentage of females ranged from 20% to 59% (median 35.8%).The overall quality of the included studies was low: randomisation methods were poorly reported and several of the included studies were subject to a high risk of performance bias and reporting bias. One trial which started in 2008 has not been published and the progress of this trial in unknown, leading to potential publication bias. The quality of evidence was therefore low or very low for all outcomes due to a high risk of bias as well as imprecision due to the low number of overall participants, and in some cases evidence based on a single study. We found that MSCs may make little or no difference in the risk of all-cause mortality in either prophylactic trials (HR 0.85, 95% CI 0.50 to 1.42; participants = 301; studies = 5; I² = 34% ; low-quality evidence) or therapeutic trials (HR 1.12, 95% CI 0.80 to 1.56; participants = 244; studies = 1; very low-quality evidence), and no difference in the risk of relapse of malignant disease (prophylactic trials: RR 1.08, 95% CI 0.73 to 1.59; participants = 323; studies = 6; I² = 0%; low-quality evidence) compared with no MSCs. MSCs were well-tolerated, no infusion-related toxicity or ectopic tissue formation was reported. No study reported health-related quality of life. In prophylactic trials, MSCs may reduce the risk of chronic GvHD (RR 0.66, 95% CI 0.49 to 0.89; participants = 283; studies = 6; I² = 0%; low-quality evidence). This means that only 310 (95% CI 230 to 418) in every 1000 patients in the MSC arm are expected to develop chronic GvHD compared to 469 in the control arm. However, MSCs may make little or no difference to the risk of aGvHD (RR 0.86, 95% CI 0.63 to 1.17; participants = 247; studies = 6; I² = 0%; low-quality evidence). In GvHD therapeutic trials, we are very uncertain whether MSCs improve complete response of either aGvHD (RR 1.16, 95% CI 0.79 to 1.70, participants = 260, studies = 1; very low-quality evidence) or cGvHD (RR 5.00, 95%CI 0.75 to 33.21, participants = 40, studies = 1; very low-quality evidence).In two trials which compared different doses of MSCs, we found no evidence of any differences in outcomes.

AUTHORS' CONCLUSIONS

MSCs are an area of intense research activity, and an increasing number of trials have been undertaken or are planned. Despite a number of reports of positive outcomes from the use of MSCs for treating acute GvHD, the evidence to date from RCTs has not supported the conclusion that they are an effective therapy. There is low-quality evidence that MSCs may reduce the risk of cGvHD. New trial evidence will be incorporated into future updates of this review, which may better establish a role for MSCs in the prevention or treatment of GvHD.

Transitional B lymphocytes are associated with protection from kidney allograft rejection: a prospective study

Recent cross-sectional studies suggest an important role for transitional B lymphocytes (CD19 + CD24hiCD38hi) in promoting transplant tolerance, and protecting from late antibody-mediated rejection (ABMR). However, prospective studies are lacking. This study enrolled 73 de novo transplant recipients, and collected serial clinical, immunological and biochemical information over 48 ± 6 months. Cell phenotyping was conducted immediately prior to transplantation, and then on five occasions during the first year posttransplantation. When modeled as a time-dependent covariate, transitional B cell frequencies (but not total B cells or "regulatory" T cells) were associated with protection from acute rejection (any Banff grade; HR: 0.60; 95% CI: 0.37-0.95; p = 0.03). No association between transitional B cell proportions and either de novo donor-specific or nondonor-specific antibody (dnDSA; dnNDSA) formation was evident, although preserved transitional B cell proportions were associated with reduced rejection rates in those patients developing dnDSA. Three episodes of ABMR occurred, all in the context of nonadherence, and all associated with in vitro anti-HLA T cell responses in an ELISPOT assay (p = 0.008 versus antibody-positive patients not experiencing ABMR). This prospective study supports the potential relevance of transitional ("regulatory") B cells as a biomarker and therapeutic intervention in transplantation, and highlights relationships between humoral immunity, cellular immunity and nonadherence.

Umbilical cord-derived mesenchymal stromal cells modulate monocyte function to suppress T cell proliferation

Mesenchymal stromal cells (MSCs) may be derived from a variety of tissues, with human umbilical cord (UC) providing an abundant and noninvasive source. Human UC-MSCs share similar in vitro immunosuppressive properties as MSCs obtained from bone marrow and cord blood. However, the mechanisms and cellular interactions used by MSCs to control immune responses remain to be fully elucidated. In this paper, we report that suppression of mitogen-induced T cell proliferation by human UC-, bone marrow-, and cord blood-MSCs required monocytes. Removal of monocytes but not B cells from human adult PBMCs (PBMNCs) reduced the immunosuppressive effects of MSCs on T cell proliferation. There was rapid modulation of a number of cell surface molecules on monocytes when PBMCs or alloantigen-activated PBMNCs were cultured with UC-MSCs. Indomethacin treatment significantly inhibited the ability of UC-MSCs to suppress T cell proliferation, indicating an important role for PGE(2). Monocytes purified from UC-MSC coculture had significantly reduced accessory cell and allostimulatory function when tested in subsequent T cell proliferation assays, an effect mediated in part by UC-MSC PGE(2) production and enhanced by PBMNC alloactivation. Therefore, we identify monocytes as an essential intermediary through which UC-MSCs mediate their suppressive effects on T cell proliferation.

Rat neurosphere cells protect axotomized rat retinal ganglion cells and facilitate their regeneration

We investigated the ability of a population of rat neural stem and precursor cells derived from rat embryonic spinal cord to protect injured neurons in the rat central nervous system (CNS). The neonatal rat optic pathway was used as a model of CNS injury, whereby retinal ganglion cells (RGCs) were axotomized by lesion of the lateral geniculate nucleus one day after birth. Neural stem and precursor cells derived from expanded neurospheres (NS) were transplanted into the lesion site at the time of injury. Application of Fast Blue tracer dye to the lesion site demonstrated that significant numbers of RGCs survived at 4 and 8 weeks in animals that received a transplant, with an average of 28% survival, though in some individual cases survival was greater than 50%. No RGCs survived in animals that received a lesion alone. Furthermore, labeled RGCs were also observed when Fast Blue was applied to the superior colliculus (SC) at 4 weeks, suggesting that neurosphere cells also facilitated RGC to regenerate to their normal target. Transplanted cells did not migrate or express neural markers after transplantation, and secreted several neurotrophic factors in vitro. We conclude that NS cells can protect injured CNS neurons and promote their regeneration. These effects are not attributable to cell replacement, and may be mediated via secretion of neurotrophic factors. Thus, neuroprotection by stem cell populations may be a more viable approach for treatment of CNS disorders than cell replacement therapy.

Building capacity for service user and carer involvement in research: the implications and impact of best research for best health

PURPOSE

The purpose of this paper is to examine the role of service user and carer involvement in NHS research and describe the nature of this involvement in three specialist mental health Trusts. It also aims to discuss the value of service user and carer involvement and present the perspective of the service user and research manager.

DESIGN/METHODOLOGY/APPROACH

The paper reviews patient and public involvement policy and practice in the NHS and NHS research. It examines the effectiveness of involvement activity and utilises a case example to demonstrate the impact of patient/service user involvement on the NHS and the individuals who take part.

FINDINGS

The paper concludes that service user involvement is essential if research is to support the development of health services that clearly reflect the needs of the service user and impact positively on service quality.

PRACTICAL IMPLICATIONS

Service user involvement is an established element of NHS research and development at both national and local level. The Department of Health strategy for research, Best Research for Best Health, reiterates both the importance of research that benefits the patient and the involvement of the service user in the research process. Despite this, the changes in Department of Health support funding for research, introduced by the strategy, may inadvertently lead to some NHS Trusts experiencing difficulty in resourcing this important activity.

ORIGINALITY/VALUE

The paper illustrates the effectiveness of successful patient and public involvement in research. It also identifies how involvement has developed in a fragmented and uncoordinated way and how it is threatened by a failure to embed it more consistently in research infrastructure.

Efficient expansion of mesenchymal stromal cells from umbilical cord under low serum conditions

BACKGROUND

Mesenchymal stromal cells (MSC) are of clinical interest for their potential use in regenerative medicine and immunotherapy. Originally derived from bone marrow (BM), MSC have now been isolated from most tissues, including umbilical cord (UC) and UC blood (UCB). If MSC from UC are biologically equivalent to those from BM, they would be attractive as a readily available and non-invasive source for cellular therapies.

METHODS

Sections of UC were separated into vascular and Wharton's jelly (WJ) fractions, which were then digested individually to release MSC that were isolated by plastic adherence in a 10% fetal calf serum (FCS) medium, or a low serum medium designed for multipotent adult progenitor cells (MAPC). The resulting perivascular (PV) and WJ MSC lines were assayed for expression of characteristic markers and differentiation and immunosuppressive properties.

RESULTS

MSC lines were readily derived from most UC tested. Cells grown in MAPC medium (MM) tended to be smaller and more elongated and expressed more nestin, but did not differ substantially in their growth rate, expression of other markers and differentiation capacity. All UC lines tested were adipogenic but poorly osteogenic, and were equivalent in their ability to suppress T-cell proliferation induced by phytohemagglutinin (PHA), activation beads and allostimulation.

CONCLUSIONS

UC is a convenient, efficient source of MSC that can be expanded under low serum conditions for application on future studies of tissue regeneration and immunosuppression.

Umbilical cord blood mesenchymal stromal cells are neuroprotective and promote regeneration in a rat optic tract model

Exploitation of the ability of stem cells to protect damaged neuronal tissue may be a more viable strategy than cell replacement for repair of the central nervous system (CNS). In this study we assessed the capacity of human umbilical cord blood (hUCB)-derived mesenchymal stromal cells (MSCs) to protect and promote regeneration of axotomised neurons within the rat optic system. The optic tract of neonatal rats was transected at the level of the lateral geniculate nucleus, and MSCs were introduced into the lesion site. MSCs survived well up to 2 weeks after grafting, and did not migrate significantly or differentiate. In the presence of MSC grafts, host axonal processes were found to be present in the lesion site, and there was stimulation of an endogenous neural precursor population. Four weeks after grafting, retrograde tracer experiments demonstrated that grafted MSCs, as well as cells of a human fibroblast line, exerted a neuroprotective effect, rescuing a significant percentage of axotomised retinal ganglion cells (RGCs). Further experiments with retrograde and anterograde tracers strongly indicated that MSCs could also promote re-growth of axotomised RGCs to their target, the superior colliculus (SC). Further analysis showed that hUCB-derived MSCs secreted several immunomodulatory and neurotrophic factors in vitro, including TGFbeta1, CNTF, NT-3 and BDNF, which are likely to play a role in neuroprotection. Our data indicate that hUCB-derived MSCs may be an easily accessible, widely available source of cells that can contribute towards neural repair through rescue and regeneration of injured neurons.

Human platelet antigen typing of neonatal alloimmune thrombocytopenia patients using whole genome amplified DNA and a 5'-nuclease assay

BACKGROUND

A serious constraint in the investigation of the human platelet antigen (HPA) status of potential neonatal alloimmune thrombocytopenia (NAIT) cases is the limited amount of DNA available from the neonates. Whole genome amplification (WGA) of these DNA samples could overcome this problem, but requires validation to ensure that it is sufficiently sensitive and accurate before its application in a clinical diagnostic setting.

STUDY DESIGN AND METHODS

This study has validated the use of WGA DNA for HPA-1, -2, -3, -4, -5, and -15 genotyping with a panel of six controls and 13 previously HPA-typed samples from neonates together with parental DNA, using a 5'-nuclease (TaqMan) assay. WGA was performed using titrated amounts of genomic and WGA DNA template. HPA typing was performed on genomic and amplified DNA using a 5'-nuclease assay or polymerase chain reaction with sequence-specific primers (PCR-SSP).

RESULTS

WGA DNA yields were in the suggested range of 400x to 800x, as assessed by spectrophotometry and gel analysis, and did not require further purification. HPA genotyping showed 100 percent concordance when using down to 5 ng of genomic or WGA template.

CONCLUSION

This study demonstrates that WGA can be used for HPA typing using PCR-SSP or plate-based 5'-nuclease assays. The use of WGA for HPA typing in clinical samples from NAIT patients was validated with 100 percent concordance, and it is suggested that this technology can be used for other analyses where DNA amounts are limited.

Molecular typing of HLA genes using whole genome amplified DNA

BACKGROUND

The outcome of clinical transplantation and a number of disease susceptibilities show very strong associations with genetic variants within the major histocompatibility complex, particularly in the human leukocyte antigen (HLA) genes. A problem with many association studies is the lack of sufficient DNA to perform multiple genetic analyses, particularly with transplantation outcomes where donor and recipient DNA are often in short supply. This study assesses whether a multiple-strand displacement whole genome amplification (WGA) method could generate sufficient template of high quality to perform unbiased amplification for analysis of the HLA-A, -B, -C, -DRB1, and -DQB1 genes.

STUDY DESIGN AND METHODS

A panel of DNA samples from various biological sources was subjected to WGA reaction using Phi29 DNA polymerase. The HLA genotypes were subsequently determined using standard polymerase chain reaction (PCR)-based methods including sequence-specific oligonucleotide probes (PCR-SSOP, Luminex, Luminex Corp.) and sequence-based typing (PCR-SBT). WGA products and original DNA samples were used to determine the sensitivity of the Luminex assay; in addition, reamplified WGA products were also genotyped.

RESULTS

The WGA templates, as well as serially amplified DNA for two successive rounds, yielded HLA genotypes fully concordant with those determined for the original DNA samples. WGA products and original DNA gave reproducible HLA-DQB1 genotypes with 100 to 10 ng of template. Purification of the WGA products was required for successful PCR-SBT, but not for the PCR-SSOP method.

CONCLUSION

Our study suggests that WGA can be a reliable method for generating unlimited DNA for medium- or high-resolution HLA typing using the techniques described above.

Analysis of neural potential of human umbilical cord blood-derived multipotent mesenchymal stem cells in response to a range of neurogenic stimuli

We investigated the neurogenic potential of full-term human umbilical cord blood (hUCB)-derived multipotent mesenchymal stem cells (MSCs) in response to neural induction media or coculture with rat neural cells. Phenotypic and functional changes were assessed by immunocytochemistry, RT-PCR, and whole-cell patch-clamp recordings. Naive MSCs expressed both mesodermal and ectodermal markers prior to neural induction. Exposure to retinoic acid, basic fibroblast growth factor, or cyclic adenosine monophosphate (cAMP) did not stimulate neural morphology, whereas exposure to dibutyryl cAMP and 3-isobutyl-1-methylxanthine stimulated a neuron-like morphology but also appeared to be cytotoxic. All protocols stimulated increases in expression of the neural precursor marker nestin, but expression of mature neuronal or glial markers MAP2 and GFAP was not observed. Nestin expression increases were serum level dependent. Electrophysiological properties of MSCs were studied with whole-cell patch-clamp recordings. The MSCs possessed no ionic currents typical of neurons before or after neural induction protocols. Coculture of hUCB-derived MSCs and rat neural cells induced some MSCs to adopt an astrocyte-like morphology and express GFAP protein and mRNA. Our data suggest hUCB-derived MSCs do not transdifferentiate into mature functioning neurons in response to the above neurogenic protocols; however, coculture with rat neural cells led to a minority adopting an astrocyte-like phenotype.

5-Azacytidine-treated human mesenchymal stem/progenitor cells derived from umbilical cord, cord blood and bone marrow do not generate cardiomyocytes in vitro at high frequencies

BACKGROUND AND OBJECTIVES

Mesenchymal stem/progenitor cells (MSCs) are multipotent progenitors that differentiate into such lineages as bone, fat, cartilage and stromal cells that support haemopoiesis. Bone marrow MSCs can also contribute to cardiac repair, although the mechanism for this is unclear. Here, we examine the potential of MSCs from different sources to generate cardiomyocytes in vitro, as a means for predicting their therapeutic potential after myocardial infarction.

MATERIALS AND METHODS

Mesenchymal stem/progenitor cells were isolated from the perivascular tissue and Wharton's jelly of the umbilical cord and from cord blood. Their immunophenotype and differentiation potential to generate osteoblasts, chondrocytes, adipocytes and cardiomyoxcytes in vitro was compared with those of bone marrow MSCs.

RESULTS

Mesenchymal stem/progenitor cells isolated from umbilical cord and cord blood were phenotypically similar to bone marrow MSCs, the exception being in the expression of CD106, which was absent on umbilical cord MSCs, and CD146 that was highly expressed in cord blood MSCs. They have variable abilities to give rise to osteoblasts, chondrocytes and adipocytes, with bone marrow MSCs being the most robust. While a small proportion (approximately 0.07%) of bone marrow MSCs could generate cardiomyocyte-like cells in vitro, those from umbilical cord and cord blood did not express cardiac markers either spontaneously or after treatment with 5-azacytidine.

CONCLUSION

Although MSCs may be useful for such clinical applications as bone or cartilage repair, the results presented here indicate that such cells do not generate cardiomyocytes frequently enough for cardiac repair. Their efficacy in heart repair is likely to be due to paracrine mechanisms.

Characterization of mesenchymal stromal cells derived from full-term umbilical cord blood

BACKGROUND

Multipotent mesenchymal stromal cells (MSC) are of interest for their potential to repair bone and cartilage, and also their immunosuppressive properties. Umbilical cord blood (UCB) is reported to contain MSC, and therefore may be a useful source of these cells for clinical applications.

METHODS

We evaluated protocols for isolating MSC from UCB and characterized the surface phenotype, differentiation potential and immunoregulatory properties of the cells obtained.

RESULTS

Ten of 25 UCB units processed yielded MSC-like colonies, with depletion of lineage+ cells providing a higher efficiency. Only two of the cultures could be expanded satisfactorily; the remainder failed to proliferate. One culture generated transformed lines that were grossly aneuploid, had up-regulated TERT transcripts and had lost CD90 expression and the capacity to differentiate. The two propagated UCB-MSC lines were similar to those from bone marrow but were not identical to each other, with differences seen in expression of surface markers and cytoskeletal proteins. Both underwent osteogenesis, but at different rates and to different degrees, while neither generated adipocytes. When added as a third party to a mixed lymphocyte culture, both suppressed proliferation.

DISCUSSION

MSC-like cells can be isolated from UCB, but at low efficiencies, and they exhibit a variety of morphologies, growth rates and differentiation potentials and can transform in culture.

Mesenchymal stem cells of cord blood origin are effective at preventing but not treating graft-versus-host disease

The immunosuppressive properties of mesenchymal stem cells (MSC) make them particularly attractive to manipulate graft-versus-host disease (GVHD). So far, the experience of using MSC to treat GVHD is limited to a few cases, controversial results come from preclinical models and several issues remain to be clarified. The present studies were designed to address these questions in a xenogenic model testing the ability of umbilical cord blood-derived MSC (UCB-MSC) to prevent and/or treat GVHD. Sublethally irradiatiated non-obese diabetic/severe combined immunodeficiency NOD/SCID mice transplanted with human peripheral blood mononuclear cells (huPBMC) showed extensive human T-cell proliferation in the peripheral blood, lymphoid and non-lymphoid tissues, which evolved in extensive GVHD (wasting, ruffled hair and hunched back). The mice treated with a single dose of UCB-MSC did not behave differently form the controls. However, when UCB-MSC were given at weekly intervals, there was a marked decrease in human T-cell proliferation and none of the mice developed GVHD. No therapeutic effect was obtained if UCB-MSC were administered at onset of GVHD. This work supports the clinical use of MSC in stem cell transplantation as a prophylaxis rather than treatment of GVHD.

The impact of service user involvement in research

PURPOSE

There are many examples of consumer involvement in NHS research but few studies have examined the impact of this on service development or the research process. This study, involving service user and carer researchers working alongside professional researchers, aimed to examine the development of one service user and carer research group in a mental health Trust. DERSIGN/METHODOLOGY/APPROACH: The research involved a review of existing literature on consumer involvement in research, a review of user involvement in research in South West Yorkshire Mental Health NHS Trust, a survey of consumers and NHS staff in the Trust, and a skills audit and training needs analysis of consumers.

FINDINGS

The study identified the range and extent of consumer involvement and the impact of this on consumers and the Trust. Service users and carers were involved in a range of projects, mainly on the level of consultation or collaboration. The benefits for consumers were principally on a personal level and included gaining knowledge and experience, improved sense of well-being, self esteem, and confidence. The benefit for the Trust was in having a service user perspective and focus. However, there is a tendency to omit service users from planning and setting priorities.

PRACTICAL IMPLICATIONS

The study pointed to the need to build the evidence base on consumer involvement in research, particularly in terms of how consumers can impact on setting research priorities and selecting appropriate methods. It identifies the need for more training for consumers and for NHS staff and for a more coherent strategy.

ORIGINALITY/VALUE

This article will be of value to anyone who is at the start or in the early stages of their journey of consumer involvement. It identifies some of the practical issues faced by consumers and staff in working collaboratively, but also points to the benefits for all the stakeholders.

Fractalkine expression on human renal tubular epithelial cells: potential role in mononuclear cell adhesion

Fractalkine (CX3CL1) is a transmembrane molecule with a CX3C chemokine domain attached to an extracellular mucin stalk which can induce both adhesion and migration of leucocytes. Mononuclear cell infiltration at renal tubular sites and associated tubular epithelial cell damage are key events during acute renal inflammation following renal allograft transplantation. Using northern and Western blot analysis, we have demonstrated the expression of fractalkine message and protein by renal tubular epithelial cells in vitro. The expression was up-regulated by TNF-alpha, a key proinflammatory cytokine in acute rejection. Investigation of surface expression of fractalkine on cultured proximal tubular epithelial cells revealed only a subpopulation of positively staining cells. Immunohistochemistry revealed that only a proportion of tubules in renal allograft biopsies showed induction of fractalkine expression. Studies using a static model of adhesion demonstrated CX3CR1/fractalkine interactions accounted for 26% of monocytic THP-1 cell and 17% of peripheral blood natural killer cell adhesion to tubular epithelial cells, suggesting that fractalkine may have a functional role in leucocyte adhesion and retention, at selected tubular sites in acute renal inflammation. Thus, fractalkine blockade strategies could reduce mononuclear cell mediated tubular damage and improve graft survival following kidney transplantation.

Fractalkine expression in human renal inflammation

Immune and inflammatory human renal disease is associated with heavy mononuclear cell infiltration. The trafficking of these cells to extravascular sites is directed by local production of chemokines. Fractalkine is the first described cell-surface anchored chemokine and has potent mononuclear cell-directed adhesion and chemotactic properties. The purpose of this study was to analyse the expression and distribution of fractalkine in human renal inflammation. In situ hybridization and immunohistochemistry were used to study renal biopsies from 15 patients with predominant glomerular inflammation (vasculitic glomerulonephritis) and 15 with predominant tubular and interstitial inflammation (acute renal allograft rejection). Controls comprised non-inflammatory glomerulonephritis and normal tissue. Fractalkine mRNA was predominantly expressed in the major compartment, glomerular or tubulointerstitial, affected by disease and with the strongest expression localized to vascular sites local to inflammation. In acute renal allograft rejection, there was increased expression of fractalkine mRNA by tubular epithelial cells. There was no expression of fractalkine by infiltrating leukocytes and there was only sparse expression in control tissue. Fractalkine mRNA expression correlated with infiltrating leukocyte subsets. Immunohistochemistry confirmed this pattern of expression, with serial section co-localization showing fractalkine expression in areas with macrophage (CD68+) and T cell (CD3+) infiltrates. These expression patterns show that fractalkine is a strong candidate for directing mononuclear cell infiltration in human renal inflammation.

Protocols for high efficiency, stage-specific retroviral transduction of murine fetal thymocytes and thymic epithelial cells

Viral vectors have the potential to provide a fast and economic alternative to transgenic methods for manipulating gene expression in studies of immune system development and function. Although protocols exist for the infection of hematopoietic precursors and peripheral T cells in vitro, critical stages of T cell differentiation are strictly dependent upon a three-dimensional thymic architecture and their analysis poses unique technical challenges. Whole fetal thymic lobes have been used as targets for retroviral and adenoviral infection, both in situ and in vitro, but this approach does not allow for discrimination between lymphoid and stromal components. Isolated thymocytes have been infected by co-culture with viral producer cells, but under these conditions they rapidly lose their developmental potential. To overcome these problems we have combined a number of efficient techniques for retroviral production, concentration, and infection that allow us to rapidly achieve significant transduction rates of purified populations of double-negative (DN) and double-positive (DP) thymocytes, single-positive (SP) T lymphocytes, as well as fetal thymic MHC II(+) epithelial cells without the need for co-culture with viral producer cells. Reaggregate thymic organ culture (RTOC) techniques were used to assess the development and function of transduced cells in defined cellular environments. As a demonstration of the utility of these methods, CD80 (B7.1) was transduced into thymic epithelial cells and shown to allow them to mediate negative selection of DP thymocytes, and to act as antigen-presenting cells (APC) to mature T cells. The ability to genetically manipulate primary cells of a specified type and differentiation stage provides a powerful complement to RTOC techniques for the study of T cell development.

Potential role for monocyte chemotactic protein-4 (MCP-4) in monocyte/macrophage recruitment in acute renal inflammation

The CC chemokine, monocyte chemoattractant protein-4 (MCP-4), is an important chemoattractant for monocytes and T cells. Recent data indicate a role in renal inflammation. This study has used in situ hybridization and immunohistochemical analysis of cryostat sections of biopsy material taken from patients with acute renal allograft rejection and vasculitic glomerulonephritis to demonstrate renal expression of MCP-4, both at message and protein level. MCP-4 was primarily expressed at peritubular, periglomerular, and perivascular sites, irrespective of the inflammatory condition, and was associated with infiltrating CD3-positive lymphocytes and CD68-positive monocyte/macrophages. In addition, proximal tubular epithelial cells grown in culture from cortical fragments of human kidney showed low levels of constitutive MCP-4 expression, detectable by western blotting; this expression of MCP-4 was up-regulated in response to the pro-inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). CCR3-, CCR5- and CCR2-expressing leukocyte populations were identified at sites of MCP-4 expression. Double-staining techniques revealed that CC chemokine receptor-expressing cells were primarily CD68-positive. These studies suggest an important role for MCP-4 in the recruitment and retention of monocytes/macrophages in renal inflammation.

Diagnosis of defects in the type 1 cytokine pathway

Patients with inherited defects in the interleukin-12 (IL-12)-dependent, 'high-output' interferon-gamma (IFN-gamma) pathway exhibit selective susceptibility to poorly pathogenic mycobacterial and salmonella infections. This review summarises the extended clinical spectrum seen in this group of patients and indicates a strategy for the identification of putative defects in the type 1 cytokine pathway.

Synergistic induction of HLA class I expression by RelA and CIITA

The major histocompatibility complex (MHC) class I genes are induced synergistically by interferons (IFN) and tumor necrosis factor (TNF), a response thought to involve the cooperative action of Rel/NF-kB and interferon regulatory factor (IRF) transcription factors. The IFN-gamma-inducible class II transcriptional activator (CIITA) has recently been shown to transactivate MHC class I as well as class II genes, and this investigation shows that CIITA synergizes strongly with RelA to stimulate HLA class I expression. The functional interaction of CIITA and RelA requires both promoter elements and the upstream Rel binding site and is not seen with a class II reporter. The promoter elements necessary for CIITA action are also required for induction by IFN-alpha. HLA-A and HLA-B loci respond differentially to IFNs, and we identify locus-specific differences in critical promoter elements in addition to known polymorphisms in the Rel and IRF binding sites. The HLA-A promoter is transactivated relatively poorly by CIITA and does not interact detectably with CREB proteins implicated in CIITA recruitment, but the synergism with RelA can compensate for this weakness. The present findings illustrate that multiple transcription factors cooperate to regulate class I expression and that their relative importance differs according to the locus and cell type examined. (Blood. 2000;95:3804-3808)

Recall antigen presentation by gamma-interferon-activated microglia results in T cell activation and propagation of the immune response

The interaction between microglia and T cells is important in the development of central nervous system inflammation. This may result in full T cell activation, a partial state of activation, anergy or apoptosis of the 'responding' T cell. Here, we demonstrate that neonatal rodent microglia not only fail to initiate a mixed lymphocyte reaction (MLR), but suppress background T cell proliferation. Even after activation with gamma-IFN or following phagocytosis, microglia remain unable to support a MLR. By contrast, gamma-IFN-activated microglia are able to activate memory T cells in a recall assay resulting in cytokine (gamma-IFN) release and modest T cell proliferation. Although the stimulation index is small, functional relevance is demonstrated. Supernatants from the recall assay stimulate gamma-IFN-dependent activation of a STAT (signal transducer and activator of transcription) factor within resting microglia. This demonstrates that memory T cells not only receive sufficient stimulation from the gamma-IFN-activated microglia to proliferate and produce cytokines, but that there is also a reciprocal stimulation of resting microglia. Importantly, this provides evidence that activated microglia have the potential to propagate immune responses in the central nervous system, but are unlikely to initiate a primary response.

A human IFNGR1 small deletion hotspot associated with dominant susceptibility to mycobacterial infection

The immunogenetic basis of severe infections caused by bacille Calmette-Guérin vaccine and environmental mycobacteria in humans remains largely unknown. We describe 18 patients from several generations of 12 unrelated families who were heterozygous for 1 to 5 overlapping IFNGR1 frameshift small deletions and a wild-type IFNGR1 allele. There were 12 independent mutation events at a single mutation site, defining a small deletion hotspot. Neighbouring sequence analysis favours a small deletion model of slipped mispairing events during replication. The mutant alleles encode cell-surface IFNgamma receptors that lack the intra-cytoplasmic domain, which, through a combination of impaired recycling, abrogated signalling and normal binding to IFNgamma exert a dominant-negative effect. We thus report a hotspot for human IFNGR1 small deletions that confer dominant susceptibility to infections caused by poorly virulent mycobacteria.

Interferon-beta mediates stromal cell rescue of T cells from apoptosis

The resolution of immune responses is characterized by extensive apoptosis of activated T cells. However, to generate and maintain immunological memory, some antigen-specific T cells must survive and revert to a resting G0/G1 state. Cytokines that bind to the common gamma chain of the IL-2 receptor promote the survival of T cell blasts, but also induce proliferation. In contrast, soluble factors secreted by stromal cells induce Tcell survival in a resting G0/G1 state. We now report that interferon-beta is the principal mediator of stromal cell-mediated Tcell rescue from apoptosis. Interferon-alpha and -beta promote the reversion of blast Tcells to a resting G0/G1 configuration with all the characteristic features of stromal cell rescue; such as high Bcl-XL expression and low Bcl-2. Type I interferons and stromal cells stimulate apparently identical signaling pathways, leading to STAT-1 activation. We also show that this mechanism may play a fundamental role in the persistence of T cells at sites of chronic inflammation; suggesting that chronic inflammation is an aberrant consequence of immunological memory.

Inherited interleukin 12 deficiency in a child with bacille Calmette-Guérin and Salmonella enteritidis disseminated infection

Interferon-gamma receptor ligand-binding chain (IFN-gammaR1) or signaling chain (IFN-gammaR2) deficiency, like interleukin 12 receptor beta1 chain (IL-12Rbeta1) deficiency, predispose to severe infections due to poorly virulent mycobacteria and salmonella. A child with bacille Calmette-Guérin and Salmonella enteritidis infection was investigated. Mutations in the genes for IFN-gammaR1, IFN-gammaR2, IL-12Rbeta1, and other molecules implicated in IL-12- or IFN-gamma-mediated immunity were sought. A large homozygous deletion within the IL-12 p40 subunit gene was found, precluding expression of functional IL-12 p70 cytokine by activated dendritic cells and phagocytes. As a result, IFN-gamma production by lymphocytes was markedly impaired. This is the first discovered human disease resulting from a cytokine gene defect. It suggests that IL-12 is essential to and appears specific for protective immunity to intracellular bacteria such as mycobacteria and salmonella.

IFN-alpha super-induction of HLA class I expression by a variant thymoma cell line involves nuclear translocation of Rel complexes

Variant thymoma lines have been described which exhibit a substantially increased level of HLA class I induction by IFN-alpha, but not by IFN-gamma, and an unchanged response of other IFN-alpha-stimulated genes (Burrone et al., EMBO J. 1985. 4: 2855-2860). We report that their amplified response correlates with the nuclear translocation of Rel transcription factors upon prolonged treatment with IFN-alpha. The variant cells contain an IkappaBalpha subset with a significantly shortened half-life, and a constitutively active form of IkappaBalpha efficiently blocks HLA class I induction. Therefore, in addition to STAT-mediated induction, prolonged exposure to IFN-alpha can affect transcription involving Rel factors, which are implicated in the regulation of numerous immune response and viral genes.

Autocrine activation by interferon-gamma of STAT factors following T cell activation

The activation of T cells requires engagement of the T cell receptor/CD3 complex and co-stimulatory molecules, and results in the triggering of several signaling pathways which lead rapidly to the nuclear translocation of several transcription factors, such as nuclear factor (NF)-kappa B and NF-AT. A result of this activation process is the induction of a number of genes, including those encoding cytokines such as interleukin-2, tumor necrosis factor-alpha, and interferon (IFN)-gamma which have important immunoregulatory effects. We report here that a DNA-binding factor containing STAT1 also becomes activated in human peripheral blood T lymphocytes or Jurkat cells, although not until 1-2 h after stimulation. Activation is delayed a further 1-2 hr when mononuclear cell cultures are stimulated by an antigen which requires processing. Appearance of the STAT1 factor is significantly reduced in the presence of cyclosporin A, and blocked by cycloheximide, indicating that its activation is dependent upon a protein(s) synthesized in response to initial signaling events. Neutralizing antiserum against IFN-gamma, but not other cytokines tested, blocked activation of the factor almost completely, and IFN-gamma was found in the culture supernatants of stimulated cells at levels at which recombinant IFN-gamma could activate the factor in naive cells. Therefore, a STAT1 transcription factor is activated by IFN-gamma synthesized and released upon stimulation of T lymphocyte populations. While Jurkat cells both secrete and respond to IFN-gamma in an autocrine loop, it seems likely that the responding cells may differ from those synthesizing this cytokine in the mononuclear cell cultures in the light of the recent report that Th1 cells lack the IFN-gamma receptor chain necessary for activation of STAT1 (Pernis, A., Gupta, S., Gollob, K.J., Garfein, E., Coffman, R.L., Schindler, C., and Rothman, P., Science 1995. 269:245).

Stimulation of thymocytes before and after positive selection results in the induction of different NF-kappa B/Rel protein complexes

Positive selection triggers the differentiation of immature CD4+8+TCRlow thymocytes into TCRhigh single-positive CD4+ or CD8+ cells and is associated with major changes in gene expression. However, little is known about the DNA binding factors controlling these fundamental changes. Here we have examined NF-kappa B/Rel subunit expression and DNA-binding activity in developing thymocytes before and after the induction of positive selection. We show that positive selection is accompanied by the strong up-regulation of c-rel mRNA expression and the constitutive activation of p50/p65 and p50/c-Rel NF-kappa B/Rel complexes, confirming the activation-like status of cells undergoing positive selection. Moreover, CD69+ cells that have initiated positive selection (but not their preselection CD4+8+TCR- precursors) respond to stimulation by the preferential activation of c-Rel-containing DNA-binding complexes. Because the different NF-kappa B/Rel dimers have distinct transcriptional activities and binding site preferences, this preferential activation of c-Rel-containing DNA-binding complexes may well have implications for the changes in gene expression and functional response associated with positive selection.

Stimulation of thymocytes before and after positive selection results in the induction of different NF-kappa B/Rel protein complexes

Positive selection triggers the differentiation of immature CD4+8+TCRlow thymocytes into TCRhigh single-positive CD4+ or CD8+ cells and is associated with major changes in gene expression. However, little is known about the DNA binding factors controlling these fundamental changes. Here we have examined NF-kappa B/Rel subunit expression and DNA-binding activity in developing thymocytes before and after the induction of positive selection. We show that positive selection is accompanied by the strong up-regulation of c-rel mRNA expression and the constitutive activation of p50/p65 and p50/c-Rel NF-kappa B/Rel complexes, confirming the activation-like status of cells undergoing positive selection. Moreover, CD69+ cells that have initiated positive selection (but not their preselection CD4+8+TCR- precursors) respond to stimulation by the preferential activation of c-Rel-containing DNA-binding complexes. Because the different NF-kappa B/Rel dimers have distinct transcriptional activities and binding site preferences, this preferential activation of c-Rel-containing DNA-binding complexes may well have implications for the changes in gene expression and functional response associated with positive selection.

Transcriptional regulation of HLA-A and -B: differential binding of members of the Rel and IRF families of transcription factors

HLA-A and -B transplantation antigens can be expressed differentially at the basal level and in response to interferons (IFNs). To determine which DNA control elements and nuclear factors are responsible for these differences, HLA-A and -B upstream regulatory regions were used in expression and mobility-shift analyses. The HLA-A enhancer was found to contain two Rel (KBF/NF-kappa B) binding motifs, while the HLA-B enhancer has only one and is transactivated less well by overexpression of the NF-kappa B p65 subunit. On the other hand, the HLA-B IFN response element mediates a much stronger induction by IFNs and has a higher affinity for IRF-1 and -2, which are transcription factors implicated in the regulation of major histocompatibility complex class I genes. These results suggest a molecular basis for the way in which HLA-A and -B loci have adapted to be differentially expressed and to respond to different sets of cytokine signals.

An HLA-B regulatory element binds a factor immunologically related to the upstream stimulation factor

HLA-A and -B are expressed by most cell types, and their levels can be increased by treatment with interferons (IFNs). The relative basal levels of HLA-A and -B expression can vary, and HLA-B loci are induced much more strongly by IFNs. Constitutive activity is dependent on an upstream enhancer (ENH) which contains a rel (KBF, NF kappa B) binding motif, and induction is mediated by an interferon response element (IRE) which binds members of the IRF family. Reported here is the identification of a regulatory element, 'R', which overlaps the IRE of HLA-B loci, but which is absent from the equivalent region of HLA-A or H2 class I genes. The core of the element, CACGAG, is bound by a nuclear factor which is recognized by an antiserum raised against the upstream stimulation factor (USF), a member of the helix-loop-helix/leucine zipper family. The use of reporter gene constructs shows that mutation of the R element results in increased induction by IFN alpha in some cell lines, which appears to be due to competitive binding of USF with IRF proteins.

HLA-J, a second inactivated class I HLA gene related to HLA-G and HLA-A. Implications for the evolution of the HLA-A-related genes

Ragoussis and co-workers (Genomics 4:301) previously described a class I HLA gene (now designated HLA-J) that maps to within 50 kb of HLA-A. The nucleotide sequences of three HLA-J alleles are reported here. Comparison of the nucleotide sequences of HLA-J alleles shows this gene is more related to HLA-G, A, and H than to HLA-B, C, E, and F. All four alleles of HLA-J are pseudogenes because of deleterious mutations that produce translation termination either in exon 2 or exon 4. Apart from these mutations, the predicted proteins have structures similar to those of HLA-A, B, and C molecules. There is, however, little polymorphism at HLA-J and none at functional positions of the Ag-recognition site. The polymorphism is less than found for HLA-H another HLA-A-related pseudogene. HLA-J appears, like HLA-H, to be an inactivated gene that result from duplication of an Ag-presenting locus related to HLA-A. Nucleotide sequence comparisons show that the HLA-A, H, J, and G genes form a well defined group of "HLA-A-related" loci. Evolutionary relationships as assessed by construction of trees suggest the four modern loci: HLA-A, G, H, and J were formed by successive duplications from a common ancestral gene. In this scheme one intermediate locus gave rise to HLA-A and H, the other to HLA-G and J.

HLA-J, a second inactivated class I HLA gene related to HLA-G and HLA-A. Implications for the evolution of the HLA-A-related genes

Ragoussis and co-workers (Genomics 4:301) previously described a class I HLA gene (now designated HLA-J) that maps to within 50 kb of HLA-A. The nucleotide sequences of three HLA-J alleles are reported here. Comparison of the nucleotide sequences of HLA-J alleles shows this gene is more related to HLA-G, A, and H than to HLA-B, C, E, and F. All four alleles of HLA-J are pseudogenes because of deleterious mutations that produce translation termination either in exon 2 or exon 4. Apart from these mutations, the predicted proteins have structures similar to those of HLA-A, B, and C molecules. There is, however, little polymorphism at HLA-J and none at functional positions of the Ag-recognition site. The polymorphism is less than found for HLA-H another HLA-A-related pseudogene. HLA-J appears, like HLA-H, to be an inactivated gene that result from duplication of an Ag-presenting locus related to HLA-A. Nucleotide sequence comparisons show that the HLA-A, H, J, and G genes form a well defined group of "HLA-A-related" loci. Evolutionary relationships as assessed by construction of trees suggest the four modern loci: HLA-A, G, H, and J were formed by successive duplications from a common ancestral gene. In this scheme one intermediate locus gave rise to HLA-A and H, the other to HLA-G and J.

Differential expression and interferon response of HLA class I genes in thymocyte lines and response variants

cDNA clones which seem to represent the alleles of HLA-A and -B expressed by the thymoma MOLT-4 have been isolated and used as locus-specific probes to measure the corresponding mRNA levels in MOLT-4 and other human thymocyte lines, and the effect of interferon (IFN)-alpha and -gamma on these levels. It is shown in MOLT-4, and in its derived line YHHH, that HLA-B mRNA levels are undetectable before treatment but respond to IFN-alpha and -gamma more markedly than those of HLA-A. This differential induction is best shown with YHHH, which is hypersensitive to IFN-alpha, where the HLA-B mRNA levels increase to a level threefold those of HLA-A. Other thymocyte lines tested also showed preferential induction by IFN-alpha of HLA-B, although the basal levels of HLA-A and -B tended to be similar. The effect of the altered ratio of HLA-A to -B mRNA on surface expression of the antigens and the correlation between basal level expression and inducibility are discussed.

Identification of early neuronal subpopulations in avian neural crest cell cultures

Gangliosides were employed as early differentiation markers to investigate how phenotypic diversity is generated in the vertebrate neutral crest cell population. Chromatographic analysis of metabolically labeled glycolipids from neural crest derivatives revealed that glia cell precursors synthesize a characteristic subset of the ganglioside types produced by dorsal root ganglion neurons. The ganglioside synthesis pattern of neural crest cultures is similar to that of glial precursors, but gangliosides characteristic of neurons are also detectable. To determine whether neuronal gangliosides are expressed by every cell in neural crest cultures, or by discrete cell subpopulations, crest cultures were stained immunocytochemically with monoclonal antibody A2B5 which recognizes a neuron-specific ganglioside in the GQ fraction. A2B5 was found to bind to about 1% of migratory stage neural crest cells isolated from neural tube explants after 1 day in culture. These A2B5+ cells were postmitotic and exhibited a uni- or bipolar neuronal morphology. A second, larger (10-20%) population of A2B5+ cells appears after culturing cells from 1-day crest cell clusters an additional 1-2 days. These cells initially have the typical small, stellate morphology of crest cells but later extend one or more processes. [3H]Thymidine incorporation and cell counting studies show that the precursors to these cells had divided at least once in culture before becoming postmitotic and expressing A2B5 immunoreactivity. The second A2B5+ population does not appear in secondary cultures of crest cell clusters isolated from 2-day-old explants of neural tubes. Another monoclonal antibody, R24, which recognizes ganglioside GD3, binds to subpopulations of both neurons and nonneurons in sensory ganglion cultures. In neural crest cultures R24 binds to a large subpopulation of cells, but not to A2B5+ ones. The significance of this immunostaining pattern is not yet understood. The early appearance of subpopulations, and the presence of heterogeneity in neural crest cultured under a variety of conditions suggest that intrinsic cellular mechanisms might generate subpopulations within the neural crest upon which environmental factors act.

Interaction of succinate--ubiquinone reductase (complex II) with (arylazido)phospholipids

The interaction of purified succinate dehydrogenase and succinate--ubiquinone reductase (complex II) with lipids was explored by using two (arylazido)phospholipids, one with the reactive nitrene in the head-group region of the bilayer [1-palmitoyl-2-(2-azido-4-nitrobenzoyl)-sn-glycero-3-[3H]phosphocholine (PLII)] and one with the nitrene on the methyl terminus of one of the fatty acid chains [1-myristoyl-2-[12-[(2-azido-4-nitrophenyl)amino]lauroyl]-sn-glycero-3-[14C]phosphocholine (PLI)]. Protein was reacted with vesicles of egg lecithin containing radioactive (arylazido)-phospholipids and the covalent cross-linking of lipid and protein induced by irradiation under UV light. Purified succinate dehydrogenase was found to bind to lipid vesicles through both subunits as both were labeled by PLII. The smaller subunit was inserted into the interior of the bilayer and labeled by PLI. Complex II was found to interact with lipid vesicles, with the smaller subunit of succinate dehydrogenase, CII-3, and CII-4 all inserted into the interior of the bilayer. The large subunit of succinate dehydrogenase was found to be held above the bilayer in complex II and not labeled by either probe. Results are used to derive a picture of the arrangement of subunits in complex II and to evaluate the utility of (arylazido)-phospholipids in membrane studies.

Positive cooperativity in a (dissected) lectin-membrane glycoprotein binding event

A transmembrane glycoprotein, glycophorin, was assembled into large liposomes that may be handled like intact cells. Under appropriate conditions, lectin binding to these simple model cells accurately mimics the positive cooperative behavior commonly reported for binding of various lectins to real cells. Hence we suggest that the simple observation of cooperativity in such a cell-surface recognition event does not necessarily imply an involvement of complex cellular machinery; rather, it may simply reflect interaction of a multivalent ligand with conformationally deformable headgroups.