Wiskott-Aldrich Syndrome: A study on 577 patients defining the genotype as a predictive biomarker for disease severity

WAS is a multifaceted monogenic disorder with a broad disease spectrum and variable disease severity and a variety of treatment options including allogeneic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT). No reliable biomarker exists to predict disease course and outcome for individual patients. A total of 577 patients with a WAS variant from 26 countries and a median follow-up of 8.9 years (0.3-71.1), totaling 6118 patient-years, were included in this international retrospective study. Overall survival (OS) of the cohort (censored at HSCT or GT) was 82% (95% CI 78-87) at 15 years and 70% (61-80) at 30 years of age. The type of variant was predictive of outcome: patients with a missense variant in exons 1 or 2 or with the intronic hotspot variant c.559+5G>A (class I variants) had a 15-year OS of 93% (89-98) and a 30-year OS of 91% (86-97), compared to 71% (62-81) and 48% (34-68) in patients with any other variant (class II; p<0.0001). The cumulative incidence rates of disease-related complications such as severe bleeding (p=0.007), life-threatening infection (p<0.0001), and autoimmunity (p=0.004) occurred significantly later in patients with a class I variant. The cumulative incidence of malignancy (p=0.6) was not different between classes I and II. This study represents the largest cohort of WAS patients studied so far. It confirms the spectrum of disease severity and quantifies the risk for specific disease-related complications. The class of variant is a biomarker to predict the outcome for WAS patients.

In vitro Generation of Cytotoxic T Cells With Potential for Adoptive Tumor Immunotherapy of Multiple Myeloma

Multiple myeloma is a life-threatening hematological malignancy, which is rarely curable by conventional therapies. Immunotherapy, using tumor antigen-specific, cytotoxic T-lymphocytes, may represent an alternative or additional treatment for multiple myeloma. In this study, we used hybrid cell lines, generated by fusion of an EBV B-lymphoblastoid cell line (B-LCL) and myeloma cells, to stimulate in vitro peripheral blood lymphocytes (PBLs) from patients with multiple myeloma. We investigated induction of antigen-specific, cytotoxic T-lymphocytes to the well-defined tumor associated antigens (TAAs) hTERT, MUC1, MAGE-C1 and CS1, which have been shown to be expressed in a high proportion of cases of multiple myeloma. HLA-A2-peptide pentamer staining, interferon-γ and perforin ELISpot assays, as well as cytotoxicity assays were used. Following several rounds of in vitro stimulation, the hybrid cell lines induced antigen-specific, cytotoxic T-lymphocytes to four candidate TAAs in PBLs from HLA-A2⁺ multiple myeloma patients, using known HLA-A2 restricted peptide epitopes of the TAAs. In contrast, the HLA-A2⁺ myeloma cell line U266 failed to induce antigen-specific, cytotoxic T-lymphocytes in vitro. Our data indicate that B-LCL/myeloma hybrid cell lines induce antigen-specific, cytotoxic T-lymphocytes in PBLs isolated from multiple myeloma patients in vitro and may represent a novel strategy for use in adoptive immunotherapy of multiple myeloma.

Physicians' knowledge, attitudes and practices towards Zika virus infection in Jordan

INTRODUCTION

Zika virus (ZIKAV) disease is a public health problem of international concern. Recent evidence has documented imported ZIKAV cases into the Middle East and the existence of ZIKAV-transmitting mosquitoes in Jordan. However, limited data exist on the role of physicians in public awareness in this regard. This study aimed to assess ZIKAV knowledge, attitudes and counseling practices (KAP) of general physicians and gynecologists in Amman, Jordan.

METHODOLOGY

In this cross-sectional study, a structured paper-based questionnaire was completed by 119 participants during 2016-2017.

RESULTS

Only 4.2% of the physicians correctly addressed ZIKAV-complication questions. A misconception of considering direct contact between individuals and breastfeeding as modes of ZIKAV transmission was observed. Only one participant correctly recognized that isolation of infected or exposed persons is not recommended. Having at least five years of experience in medical practice was the only factor that was significantly associated with a high knowledge score (P-value=0.011). Although prevention measures are the sole method to control ZIKAV spread, only 50% of participants believed in the efficacy of such measures. Despite a quarter of participants perceiving ZIKAV as a threat to their patients, none of them have counseled a patient in this regard before. The presence of an evidence of ZIKAV in Jordan and health authorities' recommendations were the most important predictors for adoption of counseling practice.

CONCLUSIONS

General physicians and gynecologists in Jordan had several gaps in knowledge of key aspects of ZIKAV disease, and there is a need for specific training programs of physicians and gynecologists.

Vitamin D3 supplementation of a high fat high sugar diet ameliorates prediabetic phenotype in female LDLR-/- and LDLR+/+ mice

INTRODUCTION

Fatty liver disease is prevalent in populations with high caloric intake. Nutritherapeutic approaches are being considered, such as supplementary Vitamin D3 , to improve aspects of metabolic syndrome, namely fatty liver disease, hyperlipidemia, and insulin resistance associated with obesity.

METHODS

We analyzed female LDLR-/- and LDLR+/+ mice on a 10-week diabetogenic diet for markers of fatty liver disease, metabolic strain, and inflammation.

RESULTS

The groups on a high fat high sugar diet with supplementary Vitamin D3 , in comparison with the groups on a high fat high sugar diet alone, showed improved transaminase levels, significantly less hypertriglyceridemia and hyperinsulinemia, and histologically, there was less pericentral hepatic steatosis. Levels of non-esterified fatty acids and lipid peroxidation products were significantly lower in the group supplemented with additional Vitamin D3 , as were systemic markers of inflammation (serum endotoxin and IL-6). M2 macrophage phenotype predominated in the group supplemented with additional Vitamin D3 . Beneficial changes were observed as early as five weeks' supplementation with Vitamin D3 and extended to restoration of high fat high sugar diet induced decrease of bone mineral density.

CONCLUSION

In summary, Vitamin D3 was a significantly beneficial dietary additive to blunt a prediabetic phenotype in diet-induced obesity of female LDLR-/- and LDLR+/+ mice.

Tumour cell conditioned medium reveals greater M2 skewing of macrophages in the absence of properdin

Introduction

The tumour microenvironment is shaped by the interaction of immune, non immune, and tumour cells present in close proximity. Tumour cells direct the development of a locally immune suppressed state, affecting the activity of anti tumour T cells and preparing the escape phase of tumour development. Macrophages in the tumour typically develop into so‐called tumour associated macrophages with a distinct profile of activities which lead to a reduction in inflammation and antigen presentation. The direct impact of tumour cell conditioned medium on the activity profile of macrophages in dependence of their complement component expression has not yet been investigated.

Methods

In our in vitro study, macrophages differentiated from bone marrows of properdin deficient and wildtype mice were stimulated with conditioned medium of a syngeneic tumour cell line, B16F10, a mouse melanoma subline.

Results

In comparison with macrophages from wildtype mice, those from congenic properdin deficient mice showed skewing towards M2 profile, encompassing mRNA expression for genes involved in arginine metabolism, production of type 2 cytokines, and relatively lower surface expression of molecules needed for antigen presentation.

Conclusions

These data suggest that properdin insufficiency promotes a tumour environment that helps the tumour evade the immune response.

The in vitro generation of multi-tumor antigen-specific cytotoxic T cell clones: Candidates for leukemia adoptive immunotherapy following allogeneic stem cell transplantation

Adoptive T-cell immunotherapy is a promising approach to manage and maintain relapse-free survival of leukemia patients, especially following allogeneic stem cell transplantation. Post-transplant adoptive immunotherapy using cytotoxic T lymphocytes (CTLs) of the donor origin provide graft-versus-tumor effects, with or without graft-versus-host disease. Myeloid leukemias express immunogenic leukemia associated antigens (LAAs); such as WT-1, PRAME, MAGE, h-TERT and others, most of them are able to induce specific T cell responses whenever associated with the proper co-stimulation. We investigated the ability of a LAA-expressing hybridoma cell line to induce CTL clones in PBMCs of HLA-matched healthy donors in vitro. The CTL clones were induced by repetitive co-culture with LAAs-expressing, HLA-A*0201(+) hybrid cell line, generated by fusion of leukemia blasts to human immortalized APC (EBV-sensitized B-lymphoblastoid cell line; HMy2). The induced cytotoxic T cell clones were phenotypically and functionally characterized by pentamer analysis, IFN-γ release ELISPOT and cellular cytotoxicity assays. All T cell lines showed robust peptide recognition and functional activity when sensitized with HLA-A*0201-restricted WT-1235-243, hTERT615-624 or PRAME100-108 peptides-pulsed T2 cells, in addition to partially HLA-matched leukemia blasts. This study demonstrates the feasibility of developing multi-tumor antigen-specific T cell lines in allogeneic PBMCs in vitro, using LAA-expressing tumor/HMy2 hybrid cell line model, for potential use in leukemia adoptive immunotherapy in partially matched donor-recipient setting.

Cowden's syndrome with immunodeficiency

BACKGROUND

Cowden's syndrome is a rare, autosomal dominant disease caused by mutations in the phosphoinositide 3-kinase and phosphatase and tensin homolog (PTEN) gene. It is associated with hamartomatous polyposis of the gastrointestinal tract, mucocutaneous lesions and increased risk of developing certain types of cancer. In addition to increased risk of tumour development, mutations in PTEN have also been associated with autoimmunity in both mice and humans. Until now, however, an association between Cowden's syndrome and immune deficiency has been reported in a single patient only.

METHODS AND RESULTS

Two patients with Cowden's syndrome and an increased frequency of infections were investigated for possible underlying immunodeficiency. In one patient, hypogammaglobulinaemia with a functional antibody deficiency was identified, while the other patient had a persisting CD4+ T cell lymphopenia (with normal antibody production).

CONCLUSIONS

Our data indicate that Cowden's syndrome may be associated with both T cell and B cell immune dysfunction. We recommend that patients with Cowden's syndrome and an increased frequency of infections are investigated for associated immunodeficiency.

On the Functional Overlap between Complement and Anti-Microbial Peptides

Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia).

Antigen presenting cell/ tumor cell fusion vaccines for cancer immunotherapy

Fusions of antigen presenting cells and tumor cells have been investigated in animal models and phase I/II clinical trials as candidate cancer vaccines. In animal studies there have been numerous reports of induction of protective immunity against a wide range of tumor types. Results of clinical trials have been less dramatic, but tumor-specific immune responses have been reported in many patients, with clinical responses to the vaccination in a subset. In this commentary article, I review the current status of antigen presenting cell/tumor cell fusion vaccines for cancer immunotherapy.

Toll-like receptor 9 activation induces expression of membrane-bound B-cell activating factor (BAFF) on human B cells and leads to increased proliferation in response to both soluble and membrane-bound BAFF

OBJECTIVES

Activation of TLR7 and TLR9 and high serum levels of BAFF have been implicated in the pathogenesis of SLE. However, little is known about the effects of TLR9 activation on BAFF expression by human B cells. We investigated the effect of the TLR9 agonist, CpG-ODN 2006, on the expression of BAFF and its receptors BAFF-R, TACI and BCMA, in isolated B cells from healthy donors.

METHODS

We used RT-PCR, flow cytometry and ELISA to investigate the expression of BAFF, and flow cytometry for BAFF-R, TACI and BCMA. Functional assays assessed the responses of resting and CpG-ODN-activated B cells to exogenous soluble and membrane-bound BAFF.

RESULTS

CpG-ODN did not induce BAFF secretion, but increased expression of membrane-bound BAFF on B cells. CpG-ODN also induced the expression of TACI and BCMA, but did not up-regulate BAFF-R expression. In functional studies, CpG-ODN sensitized human B cells to proliferate in response to exogenous BAFF. This effect was inhibited by a blocking antibody against BAFF-R, but was not inhibited by anti-TACI or anti-BCMA antibodies. Membrane-bound BAFF, induced by CpG-ODN, co-stimulated the proliferation of B cells stimulated with anti-IgM in a manner that was dependent on the expression of surface BAFF on the CpG-ODN-treated B cells.

CONCLUSION

TLR9 activation induces expression of membrane-bound BAFF on human B cells and leads to increased proliferation in response to both soluble and membrane-bound BAFF. These data extend our understanding of the role of TLR9 activation on human B cells and provide insights into the mechanisms by which TLR9 may participate in the pathogenesis of SLE.

Specific antibody deficiency in children with chronic wet cough

The prevalence and clinical significance of specific polysaccharide antibody deficiency (SAD) in children are poorly understood. The authors sought to determine the prevalence of SAD in children with chronic wet cough, through a retrospective study of all children with chronic wet cough attending our tertiary respiratory clinic over a 12-month period. Antibody levels to 13 pneumococcal serotypes were measured following vaccination with the unconjugated pneumococcal polysaccharide vaccine, Pneumovax II, and clinical data were reviewed. Twenty-four children over 2 years of age with chronic wet cough were vaccinated. Fourteen (58%) failed to mount an adequate antibody response, consistent with SAD. Children with SAD were more likely than children with normal antibody responses to require intravenous antibiotics (p=0.035) and to have abnormal chest radiographs (p=0.029). The authors conclude that SAD is present in a significant number of children with chronic wet cough. The clinical significance and long-term outcome of SAD warrant further investigation in prospective studies.

Specific polysaccharide antibody deficiency in chromosome 18p deletion syndrome and immunoglobulin A deficiency

Immunoglobulin (Ig) A deficiency has long been recognized in patients with chromosome 18 abnormalities. We present the case of a young girl in whom a chromosome 18p deletion syndrome (46,XX,del[18][p11.1]) was associated not only with IgA deficiency, but also with an inability to make antibody to the unconjugated pneumococcal polysaccharide vaccine, Pneumovax II, indicating a concomitant specific polysaccharide antibody deficiency. The patient suffered from recurrent upper respiratory tract and genitourinary infections, which were controlled by the use of prophylactic antibiotics. The association of specific polysaccharide antibody deficiency, IgA deficiency, and chromosome 18p deletion syndrome has not been described previously, and extends the immunological phenotype of antibody deficiencies associated with defects of chromosome 18. The presence of specific polysaccharide antibody deficiency should be investigated in patients with chromosome 18 abnormalities, as these patients may have a more severe spectrum of infections than patients with chromosome 18 abnormalities and selective IgA deficiency alone.

A threshold level of TLR9 mRNA predicts cellular responsiveness to CpG-ODN in haematological and non-haematological tumour cell lines

The human toll like receptor 9 (TLR9) detects differences between microbial and host DNA, based on unmethylated deoxycytidyl deoxyguanosine dinucleotide (CpG) motifs, leading to activation of both innate and adaptive immune mechanisms. The synthetic TLR9 agonist, CpG-ODN, can substitute for microbial DNA in these responses, and is in clinical trials as an immunomodulatory agent in diseases as diverse as infections, cancer and allergic disorders. Human TLR9 is expressed on cells of haematopoietic origin (principally plasmacytoid dendritic cells and B cells), but has also been described as being expressed on a number of other cell types. In order to clarify the expression and function of TLR9 in a range of cells of both haematopoietic and non-haematopoietic origin, we investigated the level of expression of TLR9 mRNA, and the ability of the cells to respond to CpG-ODN by upregulation of cell surface markers, cytokine production, cellular proliferation and activation of NFkappaB. Our data show that the cellular response to CpG-ODN depended on a threshold level of expression of TLR9. TLR9 was widely expressed amongst B cell tumours (with the exception of myeloma cell lines), but we did not find either threshold levels of expression of TLR9 or responses to CpG-ODN in several myeloma or myeloid tumour cell lines or any non-haematological tumour cell lines tested in our study. TLR9-positive cells varied significantly in their responses to CpG-ODN, and the level of TLR9 expression beyond the threshold did not correlate with the magnitude of the response to CpG-ODN. Finally, CpG-ODN induced NFkappaB activation and increased cellular proliferation in Hek293 cells that had been stably transfected with hTLR9, but did not affect the expression of surface markers or synthesis of IL-6, IL-10 or TNF-alpha. Thus both haematological and non-haematological cells expressing appropriate levels of TLR9 respond to CpG-ODN, but the nature of the TLR9-mediated response is dependent on cell type.

T-cell immunodeficiency in CHARGE syndrome

CHARGE syndrome comprises coloboma of the eye, heart defects, choanal atresia, growth and developmental retardation, genitourinary anomalies and ear and hearing defects. The association between CHARGE syndrome and T-cell immunodeficiency is recognized, but has not been reported widely in the literature. We report four patients meeting the diagnostic criteria for CHARGE syndrome, who had moderate or severe T-cell lymphopenia complicated by infections. The patients presented in Leicester, UK, between 2000 and 2007. All patients were negative for 22q11.2 deletions by FISH analysis, but mutations in the CHD7 gene were identified in three patients in whom the analysis was performed. Our cases indicate that patients with CHARGE syndrome may have a spectrum of T-cell immune deficiency, and that this association may be more common than has previously been appreciated. We recommend that all patients diagnosed with CHARGE syndrome should have lymphocyte subsets evaluated as part of their initial investigation.

CONCLUSION

Thymic hypoplasia should be included in the clinical features associated with CHARGE syndrome. All patients with CHARGE syndrome should have lymphocyte subset analysis performed, to exclude T-cell immunodeficiency.

Expression of chemokine receptors CXCR4, CXCR5 and CCR7 on B and T lymphocytes from patients with primary antibody deficiency

The interaction of chemokines and their receptors directs lymphocyte migration, and is involved in the distribution and organization of lymphocytes within lymphoid tissues. We reasoned that abnormal chemokine receptor expression might give rise to defects of lymphocyte migration into and within lymphoid tissues, and consequently be associated with defective antibody production in primary antibody deficiencies. In this study, we have investigated the expression of chemokine receptors CXCR4, CXCR5 and CCR7 on lymphocyte subpopulations (naive and memory B cells; CD4(+) and CD8(+) T cells) in a cohort of patients with primary antibody deficiency (n = 23), and compared these with a group of healthy controls (n = 19). We show that there were significant differences in both the proportions of lymphocytes expressing, and the levels of expression of, specific chemokine receptors on individual lymphocyte subpopulations between patients and controls. Furthermore, these changes appeared more pronounced in patients with more severe antibody deficiency. These data support the hypothesis that abnormal lymphocyte trafficking may be involved in the pathogenesis of primary antibody deficiencies.

Phenotypic and functional differentiation of KG-1 into dendritic-like cells

The cell line KG-1 has been used as an in vitro model for human dendritic cell (DC) differentiation. We have investigated the response of KG-1 cells to stimulation with a number of factors known to induce differentiation and/or maturation of DCs in vitro. KG-1 cells showed no differentiation in response to LPS, CpG oligodeoxynucleotide or CD40 ligation. Culture in the presence of TNF-alpha induced some differentiation, but only treatment with PMA and ionomycin (with or without prior culture in GM-CSF and IL-4) induced morphological and phenotypic changes consistent with DC-like maturation, and even these maximally differentiated KG-1 cells showed lower levels of surface marker expression, macromolecular endocytosis, and ability to stimulate in allogeneic MLR compared with in vitro monocyte-derived DCs. Our data show that KG-1 cells differentiate in vitro into cells with DC-like functional characteristics under the influence of strong inducers of cellular activation, but lack the potency of mature DCs in key aspects of professional antigen presenting cells.

Hybrid cells formed by fusion of Epstein - Barr virus-associated B-lymphoblastoid cells and either marrow-derived or solid tumour-derived cell lines display different co-stimulatory phenotypes and abilities to activate allogeneic T-cell responses in vitro

A panel of stable cell hybrids was generated by fusing a range of marrow-derived and solid tumour-derived human cell lines with the B-lymphoblastoid cell lines, HMy2 or KR4, and expression of immunologically relevant accessory and co-stimulatory molecules, and ability to stimulate allogeneic T-cell responses in vitro was investigated. Hybrid cell lines generated from three marrow-derived tumour cells consistently expressed both MHC class I and class II molecules, a range of accessory and T-cell co-stimulatory ligand molecules, including CD80 and CD86, and directly stimulated markedly enhanced T-cell proliferative responses in vitro, as compared with the parent tumour cell lines. The responses were blocked by addition of CTLA4-Ig fusion protein to the cultures, indicating a role of CD28/B7 interaction in induction of T-cell activation. By contrast, hybrid cells derived from three solid tumours only expressed MHC class II when the parent tumour cell line expressed MHC class II and consistently failed to express CD80 or CD86. These hybrid cells also stimulated greater T-cell proliferative responses in vitro than the parent tumour cell lines, although effective co-stimulation depended on the presence of responder non-T cells in the cultures. The expression of co-stimulatory ligand molecules and ability to directly stimulate strong allogeneic T-cell responses correlated with the EBV latency type of the hybrid cells. These data suggest that phenotypic and functional differences in fusion cells of professional antigen- presenting cells and tumour cells arise as a result of the parent tumour cell type.

Mechanisms of the self/non-self-survey in the defense against cancer: Potential for chemoprevention?

When compared to a reference population, several large epidemiological studies with long-term follow-up have reported a three- to five-fold increased risk of neoplasia amongst patients who have received organ transplants, with an incidence curve that rises in a linear fashion with time. The relationship between the immune system and cancer is complex. The ability to discriminate "self" from "non-self" is one of the central roles of the immune system. Since tumors arise from transformation of host cells, it is not surprising that some aspects of tumor immunity resemble autoimmunity. The immune response to tumors shares aspects of both self- and non-self-immune recognition. What accounts for the apparent failure of immunity? In this review article, we address the role of the self/non-self-survey in the immune response to tumors, we describe mechanisms of immune surveillance against tumor cells, and we discuss models of ignorance, tolerance and tumor evasion of the immune response. The overall aim of the article is to demonstrate the scope for prevention of cancer in individuals at increased risk of developing malignancy due to immune compromise. Interventional strategies may involve the use of pro-differentiation agents such as retinoids, modifiers of polyamine biosynthesis or inhibitors of cyclooxygenase isozymes.

Lymphocyte subpopulations from patients with primary antibody deficiency do not show increased telomere erosion

Telomere erosion and residual replicative capacity can be used as markers of the replicative history of somatic cells. We have investigated telomere length, in vitro replicative capacity and rate of telomere erosion in T and B lymphocyte populations from patients with primary antibody deficiency requiring immunoglobulin replacement therapy. We found no significant differences in telomere lengths of B cells, or of CD4+, CD8+, CD45RA+ (naive) and CD45RO+ (memory) T cell populations between patients and age matched controls. Overall, telomere length correlated inversely with age, and was reduced in memory (CD45RO+) as compared with naive (CD45RA+) T cells. In vitro long-term (6 months) cell cultures showed no differences between patients and controls in the mitogen-stimulated replicative potential of T cell subpopulations (CD4+, CD8+, CD45RA+, CD45RO+), or in the rates of telomere erosion with cellular replication in these cell populations. The rate of telomere erosion per population doubling in CD45RA+ cells, however, was greater than in CD45RO+ cells in both patients and controls. These data suggest that premature immune exhaustion is unlikely to represent a long-term complication of primary antibody deficiency.

Graves' disease in DiGeorge syndrome: patient report with a review of endocrine autoimmunity associated with 22q11.2 deletion

DiGeorge syndrome, which falls within a wider phenotypic spectrum associated with deletions of 22q11.2, is associated with a number of endocrine disorders. These include hypoparathyroidism, hypothyroidism and growth hormone deficiency. We report an unusual case of autoimmune hyperthyroidism (Graves' disease) presenting in a 3 year-old male with DiGeorge syndrome. The development of endocrine specific autoimmune disease in a syndrome associated with immune deficiency and the spectrum of endocrine autoimmunity associated with deletions of 22q11.2 are described. Paediatricians and patients with 22q11.2 deletions should be particularly aware of the risks of developing disorders of thyroid function.

T-cell telomere length maintained in HIV-infected long-term survivors

BACKGROUND AND METHODS

We have used the erosion of telomeric DNA as a measure of cellular division to study the replicative history of isolated T-lymphocyte subpopulations from a group of HIV-infected long-term survivors and age-matched healthy controls.

RESULTS

In keeping with previous studies, we found that CD45RO+ (memory) T-cells showed greater telomere erosion than CD45RA+ (naive) T-cells. We did not, however, find any significant differences in the telomere lengths of isolated CD4+, CD8+, CD45RA+ or CD45RO+ T-cells between HIV-infected long-term survivors and age-matched controls. Further, we found no evidence of telomerase activation in T-cells from the HIV-infected groups to account for the lack of telomere erosion.

CONCLUSIONS

Our data show no evidence, through telomere shortening, of clonal exhaustion or replicative senescence due to an increased rate of immune cell turnover in HIV-infected long-term survivors.

The relationship between angiogenesis and the immune response in carcinogenesis and the progression of malignant disease

Recent studies have demonstrated that angiogenesis and suppressed cell-mediated immunity (CMI) play a central role in the pathogenesis of malignant disease facilitating tumour growth, invasion and metastasis. In the majority of tumours, the malignant process is preceded by a pathological condition or exposure to an irritant which itself is associated with the induction of angiogenesis and/or suppressed CMI. These include: cigarette smoking, chronic bronchitis and lung cancer; chronic oesophagitis and oesophageal cancer; chronic viral infections such as human papilloma virus and ano-genital cancers, chronic hepatitis B and C and hepatocellular carcinoma, and Epstein-Barr virus (EBV) and lymphomas; chronic inflammatory conditions such as Crohn's disease and ulcerative colitis and colorectal cancer; asbestos exposure and mesothelioma and excessive sunlight exposure/sunburn and malignant melanoma. Chronic exposure to growth factors (insulin-like growth factor-I in acromegaly), mutations in tumour suppressor genes (TP53 in Li Fraumeni syndrome) and long-term exposure to immunosuppressive agents (cyclosporin A) may also give rise to similar environments and are associated with the development of a range of solid tumours. The increased blood supply would facilitate the development and proliferation of an abnormal clone or clones of cells arising as the result of: (a) an inherited genetic abnormality; and/or (b) acquired somatic mutations, the latter due to local production and/or enhanced delivery of carcinogens and mutagenic growth factors. With progressive detrimental mutations and growth-induced tumour hypoxia, the transformed cell, to a lesser or greater extent, may amplify the angiogenic process and CMI suppression, thereby facilitating further tumour growth and metastasis. There is accumulating evidence that long-term treatment with cyclo-oxygenase inhibitors (aspirin and indomethacin), cytokines such as interferon-alpha, anti-oestrogens (tamoxifen and raloxifene) and captopril significantly reduces the incidence of solid tumours such as breast and colorectal cancer. These agents are anti-angiogenic and, in the case of aspirin, indomethacin and interferon-alpha have proven immunomodulatory effects. Collectively these observations indicate that angiogenesis and suppressed CMI play a central role in the development and progression of malignant disease.

Human antigen-presenting cell/tumour cell hybrids stimulate strong allogeneic responses and present tumour-associated antigens to cytotoxic T cells in vitro

Most tumours do not stimulate effective antitumour immune responses in vivo. In order to enhance the immunogenicity of human tumour cells, we fused a variety of tumour cell lines with an Epstein-Barr virus transformed B-lymphoblastoid cell line (EBV B-LCL) in vitro, to produce stable hybrid cells. Hybrid cell lines showed a marked increase in their ability to stimulate primary allogeneic T-cell responses in vitro, as compared with the parent tumour cells. The hybrid cells induced proliferation of naive (CD45RA+) as well as memory (CD45RO+) T lymphocytes, and both CD4+ and CD8+ subpopulations of T cells were directly stimulated. The stimulatory hybrids expressed human leucocyte antigen (HLA) class I and II, and a wide range of surface accessory molecules, including the T-cell co-stimulatory ligand molecules CD40, CD80 (B7.1) and CD86 (B7.2), the expression of which was required for optimal stimulation of T-cell responses. Fusion of the EBVB-LCL with a melanoma cell line (518.A2) yielded hybrid cells that expressed the melanoma-associated antigens MAGE-1 and MAGE-3, and presented these antigens to antigen-specific, HLA class I-restricted cytotoxic T-lymphocyte clones with greater efficiency than the parent melanoma cell line. These findings suggest that the generation of human antigen-presenting cell/tumour cell hybrids offers promise as an approach to cancer immunotherapy.

Adenosine, inosine, and guanosine protect glial cells during glucose deprivation and mitochondrial inhibition: correlation between protection and ATP preservation

The purpose of this study was to determine the mechanism by which adenosine, inosine, and guanosine delay cell death in glial cells (ROC-1) that are subjected to glucose deprivation and mitochondrial respiratory chain inhibition with amobarbital (GDMI). ROC-1 cells are hybrid cells formed by fusion of a rat oligodendrocyte and a rat C6 glioma cell. Under GDMI, ATP was depleted rapidly from ROC-1 cells, followed on a much larger time scale by a loss of cell viability. Restoration of ATP synthesis during this interlude between ATP depletion and cell death prevented further loss of viability. Moreover, the addition of adenosine, inosine, or guanosine immediately before the amobarbital retarded the decline in ATP and preserved cell viability. The protective effects on ATP and viability were dependent on nucleoside concentration between 50 and 1,500 microM. Furthermore, protection required nucleoside transport into the cell and the continued presence of nucleoside during GDMI. A significant positive correlation between ATP content at 16 min and cell viability at 350 min after the onset of GDMI was established (r = 0.98). Modest increases in cellular lactate levels were observed during GDMI (1.2 nmol/mg/min lactate produced); however, incubation with 1,500 microM inosine or guanosine increased lactate accumulation sixfold. The protective effects of inosine and guanosine on cell viability and ATP were >90% blocked after treatment with 50 microM BCX-34, a nucleoside phosphorylase inhibitor. Accordingly, lactate levels also were lower in BCX-34-treated cells incubated with inosine or guanosine. We conclude that under GDMI, the ribose moiety of inosine and guanosine is converted to phosphorylated glycolytic intermediates via the pentose phosphate pathway, and its subsequent catabolism in glycolysis provides the ATP necessary for maintaining plasmalemmal integrity.

Expression of a single-chain HLA class I molecule in a human cell line: presentation of exogenous peptide and processed antigen to cytotoxic T lymphocytes

We have synthesized a recombinant gene encoding a single-chain HLA-A2/beta 2-microglobulin (beta 2m) molecule by linking beta 2m through its carboxyl terminus via a short peptide spacer to HLA-A2 (A*0201). This gene has been expressed in the beta 2m-deficient colorectal tumor cell line DLD-1. Transfection of this cell with the single-chain construct was associated with conformationally correct cell surface expression of a class I molecule of appropriate molecular mass. The single-chain HLA class I molecule presented either exogenously added peptide or (after interferon-gamma treatment) endogenously processed antigen to an influenza A matrix-specific, HLA-A2-restricted cytotoxic T-lymphocyte line. The need for interferon gamma for the processing and presentation of endogenous antigen suggests that DLD-1 has an antigen-processing defect that can be up-regulated, a feature that may be found in other carcinomas. Our data indicate that single-chain HLA class I constructs can form functional class I molecules capable of presenting endogenously processed antigens. Such molecules should be of use for functional studies, as well as providing potential anticancer immunotherapeutic agents or vaccines.

Phototyping: comprehensive DNA typing for HLA-A, B, C, DRB1, DRB3, DRB4, DRB5 & DQB1 by PCR with 144 primer mixes utilizing sequence-specific primers (PCR-SSP)

We have developed a single DNA typing method which uses 144 sequence-specific primer (SSP) reactions to simultaneously detect all known HLA-A, B, C, DRB1, DRB3, DRB4, DRB5 and DQB1 specificities in an allele specific or group specific manner using the same method, reagents, PCR parameters and protocols for all loci. The results from this integrated class I & II method can be visualized on a single photographic or electronic image and hence is described as "Phototyping". Phototyping has an overall resolution greater than or equivalent to good serology and results can be obtained in under 3 hours making the method suitable for genotyping potential cadaver donor peripheral blood without serological backup. This in turn produces the potential for reducing cold ischaemia times in renal transplantation as well as the application of prospective matching to cardiac and liver transplantation. The method has capacity to detect new alleles, for example, novel amplification patterns suggestive of 4 new HLA-B alleles have been detected. The Phototyping set has been used as the sole method of HLA typing for over 1010 individuals. Phototyping is not problem-free; deviations from the standard protocol, poor quality DNA and unsuitable PCR machines can result in individual PCR failures or in incorrect assignment of antigens. Approximately 5% of genotypes were repeated (either partially or fully) because of incomplete or equivocal results.

Defining the allelic variants of HLA-A30 in the Sardinian population using amplification refractory mutation system--polymerase chain reaction

HLA-A30 is present in the Sardinian population at a frequency of 23%. We have designed a system using nested ARMS-PCR to determine the relative frequencies of the HLA-A*30 allelic variants (A*3001, A*3002, and A*3003) within this population. The use of a nested PCR approach, in which the first-round reaction provides HLA-A*30 specificity and template DNA for the subsequent nested reactions, is a powerful means of discriminating between alleles of very similar sequence. Using this method, we performed subtyping of 35 serologically defined HLA-A30 Sardinian individuals, and taking into account homozygotes, identified 38 A*30 alleles. Of these, 33 typed as A*3002, four typed as A*3001, and one sample did not conform to the patterns of reactivity of any of the published A*30 alleles. Haplotype information showed strong linkage disequilibrium between A*3002 and B18. This study underlines the potential of DNA-based methods for typing HLA class I in terms of adding further levels of definition to studies of population structure and also as a means of identifying new alleles.

The HLA-A,B,C genotype of the class I negative cell line Daudi reveals novel HLA-A and -B alleles

Daudi, a lymphoblastoid B cell line derived from an African Burkitt lymphoma does not express HLA-A,B,C antigens at the cell surface. Although HLA-A,B,C heavy chains are made normally they do not assemble into functional molecules because beta 2-microglobulin is absent. Previous serological analysis of somatic cell hybrids indicated that the HLA haplotypes of Daudi encoded HLA-A1, A10(A26), B17, and B16(38) antigens. Here we describe the application of molecular methods: ARMS-PCR, cDNA cloning and sequencing, immunoprecipitation and gel electrophoresis, to define the class I genotype of the Daudi cell line which is HLA-A*0102, A*6601, B*5801, B*5802, Cw*0302 and Cw*0602. With the exception of the B38 antigen, which is not a product of the alleles defined, the genotype is consistent with the serological description. Two previously undiscovered alleles emerged from this analysis: A*0102 and B*5802. The A*0102 allele differs from A*0101 by 5 nucleotide substitutions within exon 2 where it has a motif shared with A*30 alleles; the B*5802 allele differs from B*5801 by 3 substitutions in exon 3 where it has a motif shared with B*14 alleles. Subtyping HLA-A1 alleles showed A*0102 was well represented amongst individuals typed serologically as A1 in an African population but was absent from caucasoids. B*5802 has been found in a second individual. Thus the novel A and B alleles are not specific to the Daudi tumor. Overall, this analysis of a single East African cell illustrates the power of molecular methods to define new class I HLA alleles in non-caucasoid populations.

Low-resolution DNA typing for HLA-B using sequence-specific primers in allele- or group-specific ARMS/PCR

The products of the human major histocompatibility complex (HLA Class I and II) have historically been detected using serological or cellular assays. With the availability of DNA sequence information for alleles of the HLA system, and with the development of molecular biological techniques it has become possible to tissue type for allelic differences in the HLA genes themselves. We describe here a polymerase chain reaction (PCR) system, based on the principle of the amplification refractory mutation system (ARMS), for low-resolution DNA typing of the HLA-B gene. The technique involves a one-step PCR from genomic DNA using sequence-specific primers in particular combinations that determine the specificity of each reaction. A low-resolution primer panel has been designed, based on published HLA-B gene nucleotide sequences, consisting of 34 sequence-specific primers (SSP) in 24 PCR reactions which cover all known HLA-B alleles, to give allele-specific or group-specific amplification of DNA fragments of defined size (344-784bp). Advantages of the system are that it can be performed in under 4 hours including DNA extraction, results are easy to interpret and it does not require viable cells.

HLA-A locus DNA typing of the 4AOH cell panel by arms PCR

As part of the Fourth Asia-Oceania Histocompatibility (4AOH) Workshop, the authors have demonstrated a method of DNA-based tissue typing of the HLA-A locus using ARMS-designed primers in a panel of specific PCR reactions. The study was carried out blind under Workshop conditions and the results confirm the method as an accurate means of determining HLA-A locus tissue types.

Loss of human leukocyte antigen expression on colorectal tumor cell lines: implications for anti-tumor immunity and immunotherapy

A system devised for tissue typing the human leukocyte antigen-A (HLA-A) locus from genomic DNA by the polymerase chain reaction (PCR) has been used to investigate abnormalities of HLA expression in a panel of 30 cell lines derived from colorectal adenocarcinomas, by comparison of the HLA-A locus genotype with surface expression of HLA. Eleven cell lines gave single HLA-A locus specificity on PCR typing, suggesting that loss of HLA alleles is a common abnormality. In one of these cell lines the loss of an HLA-A locus allele was confirmed by comparison with DNA from a lymphoblastoid B cell line derived from the same patient. In three cell lines, loss of expression of an HLA-A locus determinant was observed in spite of the presence of the relevant allele in genomic DNA. Three cell lines showed absent HLA expression associated with failure to express beta 2-microglobulin. These data indicate that at least three independent mechanisms were involved in the loss of HLA expression on the colorectal tumor cell lines.

Defining the common subtypes of HLA A9, A10, A28 and A19 by use of ARMS/PCR

We describe sequence-specific primer (SSP) combinations for use in a one-step polymerase chain reaction (PCR) typing system to determine HLA-A locus subtypes of A9 (A23, A24), A10 (A25, A26, A43), A28 (A*6801, A*6802, A*6901) and A19 (A*2901, A*2902, A*3001, A*3002, A31, A32, A33) from genomic DNA. SSP's were designed on the basis of the amplification refractory mutation system (ARMS) in which a mismatch at the 3' residue inhibits non-specific amplification. The SSP combinations described extend our low-resolution typing system, to provide a high-definition typing of the HLA-A locus.

Tissue typing the HLA-A locus from genomic DNA by sequence-specific PCR: comparison of HLA genotype and surface expression on colorectal tumor cell lines

A system devised for tissue typing the HLA-A locus by PCR from genomic DNA has been used to investigate abnormalities of HLA expression in a panel of 30 colorectal tumor cell lines, by comparing the HLA-A locus genotype with surface expression of HLA. Three cell lines showed complete lack of HLA expression associated with failure to express beta 2-microglobulin. In two other cell lines, loss of expression of HLA-A2 was observed, in spite of the presence of the gene in genomic DNA. Eleven cell lines gave a single HLA-A locus specificity on PCR typing. In one of these cell lines we have demonstrated the loss of an HLA-A locus gene in the tumor cell by comparison with DNA from a lymphoblastoid B-cell line derived from the same patient. These data indicate that at least three independent mechanisms were involved in the loss of HLA expression on the colorectal tumor cell lines.

A recombinant feline immunodeficiency virus envelope fusion protein stimulates peripheral blood lymphocytes from naive cats to proliferate in vitro

A region of feline immunodeficiency virus (FIV)/Glasgow-8 external envelope glycoprotein (env) incorporating the third and fourth variable regions (V3/V4) was cloned, inserted into the pGEX vector and expressed in Escherichia coli to yield milligram quantities of the recombinant polypeptide as a fusion protein with glutathione S-transferase. The fusion protein V3/V4GST was used in lymphocyte proliferation assays, where it consistently caused peripheral blood lymphocytes from naive cats to proliferate in a dose-dependent manner. Other FIV fusion proteins produced under identical conditions (V5GST and p24GST) and glutathione S-transferase alone did not cause proliferation in this system. The monoclonal antibody vpg15, which has been shown to block infection of susceptible cells in vitro, did not decrease the response to V3/V4GST. Human peripheral blood lymphocytes did not proliferate in response to V3/V4GST.