Inborn errors of TLR3- or MDA5-dependent type I IFN immunity in children with enterovirus rhombencephalitis.

Enterovirus (EV) infection rarely results in life-threatening infection of the central nervous system. We report two unrelated children with EV30 and EV71 rhombencephalitis. One patient carries compound heterozygous TLR3 variants (loss-of-function F322fs2* and hypomorphic D280N), and the other is homozygous for an IFIH1 variant (loss-of-function c.1641+1G>C). Their fibroblasts respond poorly to extracellular (TLR3) or intracellular (MDA5) poly(I:C) stimulation. The baseline (TLR3) and EV-responsive (MDA5) levels of IFN-ß in the patients' fibroblasts are low. EV growth is enhanced at early and late time points of infection in TLR3- and MDA5-deficient fibroblasts, respectively. Treatment with exogenous IFN-α2b before infection renders both cell lines resistant to EV30 and EV71, whereas post-infection treatment with IFN-α2b rescues viral susceptibility fully only in MDA5-deficient fibroblasts. Finally, the poly(I:C) and viral phenotypes of fibroblasts are rescued by the expression of WT TLR3 or MDA5. Human TLR3 and MDA5 are critical for cell-intrinsic immunity to EV, via the control of baseline and virus-induced type I IFN production, respectively.

Infection-induced inflammation from specific inborn errors of immunity to COVID-19.

Inborn errors of immunity (IEIs) are a group of genetically defined disorders leading to defective immunity. Some IEIs have been linked to mutations of immune receptors or signaling molecules, resulting in defective signaling of respective cascades essential for combating specific pathogens. However, it remains incompletely understood why in selected IEIs, such as X-linked lymphoproliferative syndrome type 2 (XLP-2), hypo-immune response to specific pathogens results in persistent inflammation. Moreover, mechanisms underlying the generation of anticytokine autoantibodies are mostly unknown. Recently, IEIs have been associated with coronavirus disease 2019 (COVID-19), with a small proportion of patients that contract severe COVID-19 displaying loss-of-function mutations in genes associated with type I interferons (IFNs). Moreover, approximately 10% of patients with severe COVID-19 possess anti-type I IFN-neutralizing autoantibodies. Apart from IEIs that impair immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), SARS-CoV-2 encodes several proteins that suppress early type I IFN production. One primary consequence of the lack of type I IFNs during early SARS-CoV-2 infection is the increased inflammation associated with COVID-19. In XLP-2, resolution of inflammation rescued experimental subjects from infection-induced mortality. Recent studies also indicate that targeting inflammation could alleviate COVID-19. In this review, we discuss infection-induced inflammation in IEIs, using XLP-2 and COVID-19 as examples. We suggest that resolving inflammation may represent an effective therapeutic approach to these diseases.

ß3-Adrenoreceptors as ROS Balancer in Hematopoietic Stem Cell Transplantation.

In the last decades, the therapeutic potential of hematopoietic stem cell transplantation (HSCT) has acquired a primary role in the management of a broad spectrum of diseases including cancer, hematologic conditions, immune system dysregulations, and inborn errors of metabolism. The different types of HSCT, autologous and allogeneic, include risks of severe complications including acute and chronic graft-versus-host disease (GvHD) complications, hepatic veno-occlusive disease, lung injury, and infections. Despite being a dangerous procedure, it improved patient survival. Hence, its use was extended to treat autoimmune diseases, metabolic disorders, malignant infantile disorders, and hereditary skeletal dysplasia. HSCT is performed to restore or treat various congenital conditions in which immunologic functions are compromised, for instance, by chemo- and radiotherapy, and involves the administration of hematopoietic stem cells (HSCs) in patients with depleted or dysfunctional bone marrow (BM). Since HSCs biology is tightly regulated by oxidative stress (OS), the control of reactive oxygen species (ROS) levels is important to maintain their self-renewal capacity. In quiescent HSCs, low ROS levels are essential for stemness maintenance; however, physiological ROS levels promote HSC proliferation and differentiation. High ROS levels are mainly involved in short-term repopulation, whereas low ROS levels are associated with long-term repopulating ability. In this review, we aim summarize the current state of knowledge about the role of ß3-adrenoreceptors (ß3-ARs) in regulating HSCs redox homeostasis. ß3-ARs play a major role in regulating stromal cell differentiation, and the antagonist SR59230A promotes differentiation of different progenitor cells in hematopoietic tumors, suggesting that ß3-ARs agonism and antagonism could be exploited for clinical benefit.

Stem Cell-Based Disease Models for Inborn Errors of Immunity.

The intrinsic capacity of human hematopoietic stem cells (hHSCs) to reconstitute myeloid and lymphoid lineages combined with their self-renewal capacity hold enormous promises for gene therapy as a viable treatment option for a number of immune-mediated diseases, most prominently for inborn errors of immunity (IEI). The current development of such therapies relies on disease models, both in vitro and in vivo, which allow the study of human pathophysiology in great detail. Here, we discuss the current challenges with regards to developmental origin, heterogeneity and the subsequent implications for disease modeling. We review models based on induced pluripotent stem cell technology and those relaying on use of adult hHSCs. We critically review the advantages and limitations of current models for IEI both in vitro and in vivo. We conclude that existing and future stem cell-based models are necessary tools for developing next generation therapies for IEI.

Mannan-binding lectin promotes keratinocyte to produce CXCL1 and enhances neutrophil infiltration at the early stages of psoriasis.

Psoriasis is a chronic, relapsing inflammatory skin disorder. Numerous experimental evidence and therapeutic evidence have shown that the innate immune response is critical for the pathogenesis and development of psoriasis. Mannan-binding lectin (MBL), a prototypic pattern recognition molecule of the innate immune system, plays an essential role in the host defense against certain infections and also appears to be a major regulator of inflammation. In this study, we investigated the function of MBL on the course of experimental murine imiquimod (IMQ)-induced psoriasis. Our data showed that MBL-deficient (MBL-/- ) mice exhibited attenuated skin damage characterized by greatly decreased erythema compared with wild-type control mice during the early stages of IMQ-induced psoriasis-like skin inflammation. The reduced skin inflammation in MBL-/- mice was associated with the decreased infiltration of neutrophils. Furthermore, we have determined that MBL deficiency limited the chemokine CXCL1 production from skin keratinocytes upon IMQ stimulation, which might be responsible for the impaired skin recruitment of neutrophils. Additionally, we have provided the data that MBL protein promotes the IMQ-induced expression of CXCL1 and activation of MAPK/NF-κB signalling pathway in human keratinocyte HaCaT cells in vitro. In summary, our study revealed an unexpected role of MBL on keratinocyte function in skin, thus offering a new insight into the pathogenic mechanisms of psoriasis.

A General Introduction to Glucocorticoid Biology.

Glucocorticoids (GCs) are steroid hormones widely used for the treatment of inflammation, autoimmune diseases, and cancer. To exert their broad physiological and therapeutic effects, GCs bind to the GC receptor (GR) which belongs to the nuclear receptor superfamily of transcription factors. Despite their success, GCs are hindered by the occurrence of side effects and glucocorticoid resistance (GCR). Increased knowledge on GC and GR biology together with a better understanding of the molecular mechanisms underlying the GC side effects and GCR are necessary for improved GC therapy development. We here provide a general overview on the current insights in GC biology with a focus on GC synthesis, regulation and physiology, role in inflammation inhibition, and on GR function and plasticity. Furthermore, novel and selective therapeutic strategies are proposed based on recently recognized distinct molecular mechanisms of the GR. We will explain the SEDIGRAM concept, which was launched based on our research results.

Involvement of pentraxin-3 in anti-neutrophil cytoplasmic antibody production induced by aluminum salt adjuvant.

OBJECTIVES: Pentraxin 3 (PTX3) is a multifunctional soluble factor. PTX3 can be involved in the regulation of vasculitis and is expressed in the cytoplasm of neutrophils. As anti-neutrophil cytoplasmic antibody (ANCA) is recognised as a cause of vasculitis, we aimed to discover the role of PTX3 in ANCA production in vivo. METHODS: To this end, we used aluminum salt (alum), which induces neutrophil extracellular traps, as an adjuvant for producing anti-myeloperoxidase-ANCA (MPO-ANCA). Specifically, we intraperitoneally injected alum and recombinant MPO (rMPO) into MPO-deficient mice and then measured the concentration of anti-MPO IgG in their blood. To show the involvement of extracellular PTX3 in this model, we assessed PTX3 protein content and host double-stranded DNA levels in the mice's peritoneal fluid after alum injection. In addition, we simultaneously administered recombinant PTX3, rMPO and alum to MPO-deficient mice to assess the function of PTX3 in producing anti-MPO IgG in vivo. RESULTS: Anti-MPO IgG was produced by the alum + rMPO immunisation model in MPO-deficient but not wildtype mice. Injection of alum induced extracellular PTX3 as well as double-stranded DNA and dead cells in MPO-deficient mice. Simultaneous injection of recombinant PTX3 with rMPO and alum attenuated the production of anti-MPO IgG in MPO-deficient mice. CONCLUSIONS: Our current findings provide evidence that PTX3 attenuates the production of murine MPO-ANCA.

Recurrent respiratory tract infections (RRTI) in the elderly: A late onset mild immunodeficiency?

Elderly with late-onset recurrent respiratory tract infections (RRTI) often have specific anti-polysaccharide antibody deficiency (SPAD). We hypothesized that late-onset RRTI is caused by mild immunodeficiencies, such as SPAD, that remain hidden through adult life. We analyzed seventeen elderly RRTI patients and matched controls. We determined lymphocyte subsets, expression of BAFF receptors, serum immunoglobulins, complement pathways, Pneumovax-23 vaccination response and genetic variations in BAFFR and MBL2. Twelve patients (71%) and ten controls (59%) had SPAD. IgA was lower in patients than in controls, but other parameters did not differ. However, a high percentage of both patients (53%) and controls (65%) were MBL deficient, much more than in the general population. Often, MBL2 secretor genotypes did not match functional deficiency, suggesting that functional MBL deficiency can be an acquired condition. In conclusion, we found SPAD and MBL deficiency in many elderly, and conjecture that at least the latter arises with age.

Association between TLR2/TLR4 gene polymorphisms and COPD phenotype in a Greek cohort.

BACKGROUND: Considering that the innate immune system plays a pivotal role in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that functional single-nucleotide polymorphisms (SNPs) of innate immune genes affect the disease phenotype and prognosis. AIM: To elucidate the contribution of common functional TLR2 and TLR4 SNPs and genotypic deficiency of the mannose-binding lectin (MBL) protein, both as single parameters and in combination, in Greek COPD patients. RESULTS: In a cohort of 114 Greek COPD patients, we confirmed that the presence of TLR4-D299G or TLR4-T399I SNPs was significantly associated with an earlier COPD stage (p = 0.003 and p = 0.009, respectively). In comparison, the absence of any analyzed polymorphism, including those of TLR2-R753Q and genotypic MBL deficiency, was significantly associated with a more severe disease phenotype, characterized by more frequent exacerbations (p = 0.045). CONCLUSION: Our findings support the notion that the presence of innate immune SNPs, such as functional polymorphisms of TLRs along with MBL deficiency, might exert a protective effect on the COPD phenotype, similar with other immune-mediated disorders.

Cytokine-Induced Glucocorticoid Resistance from Eosinophil Activation: Protein Phosphatase 5 Modulation of Glucocorticoid Receptor Phosphorylation and Signaling.

The mechanisms contributing to persistent eosinophil activation and poor eosinopenic response to glucocorticoids in severe asthma are poorly defined. We examined the effect of cytokines typically overexpressed in the asthmatic airways on glucocorticoid signaling in in vitro activated eosinophils. An annexin V assay used to measure eosinophil apoptosis showed that cytokine combinations of IL-2 plus IL-4 as well as TNF-α plus IFN-γ, or IL-3, GM-CSF, and IL-5 alone significantly diminished the proapoptotic response to dexamethasone. We found that IL-2 plus IL-4 resulted in impaired phosphorylation and function of the nuclear glucocorticoid receptor (GCR). Proteomic analysis of steroid sensitive and resistant eosinophils identified several differentially expressed proteins, namely protein phosphatase 5 (PP5), formyl peptide receptor 2, and annexin 1. Furthermore, increased phosphatase activity of PP5 correlated with impaired phosphorylation of the GCR. Importantly, suppression of PP5 expression with small interfering RNA restored proper phosphorylation and the proapoptotic function of the GCR. We also examined the effect of lipoxin A4 on PP5 activation by IL-2 plus IL-4. Similar to PP5 small interfering RNA inhibition, pretreatment of eosinophils with lipoxin A4 restored GCR phosphorylation and the proaptoptotic function of GCs. Taken together, our results showed 1) a critical role for PP5 in cytokine-induced resistance to GC-mediated eosinophil death, 2) supported the dependence of GCR phosphorylation on PP5 activity, and 3) revealed that PP5 is a target of the lipoxin A4-induced pathway countering cytokine-induced resistance to GCs in eosinophils.

Salivary agglutinin is the major component in human saliva that modulates the lectin pathway of the complement system.

Saliva interacts with blood after mucosal damage or leakage of gingival crevicular fluid. Surface-adsorbed salivary agglutinin (SAG) activates the lectin pathway (LP) of the complement system via mannose-binding lectin, while SAG in solution inhibits complement activation. In the present study we investigated if, next to SAG, whole and glandular saliva itself and other salivary glycoproteins activate or inhibit the LP. Complement activation was measured by detecting C4 deposition on microtiter plates coated with saliva or purified proteins. Complement inhibition was measured after incubating serum with saliva or proteins in microtiter plates coated with mannan, an LP activator. Adsorbed whole, sublingual and submandibular saliva showed LP-dependent complement activation. Blood group secretors, but not non-secretors, activated the LP. Saliva of both secretors and non-secretors inhibited C4 deposition on mannan. After depletion of SAG, saliva no longer inhibited the LP. Other salivary proteins, including amylase, MUC5B and histatin 2, did not activate or inhibit the LP. Surface-adsorbed whole saliva and glandular saliva samples activate the LP of complement, depending on the presence of SAG and the secretor status of the donor. In solution, saliva inhibits the LP, depending on the presence of SAG, but independent of the secretor status.

Mannose-binding lectin (MBL) insufficiency protects against the development of systemic inflammatory response after pediatric cardiac surgery.

We investigated MBL2 and MASP2 genotypes, serum MBL (mannose-binding lectin) levels and activities of its complexes with associated serine proteases (MASP-1, MASP -2), in relation to complications following cardiac surgery in 195 children. The incidence of SIRS was lower in patients carrying MBL2 A/O and O/O genotypes (p=0.024). Children with MBL levels <500ng/ml had a lower risk of SIRS (p=0.014) and fever (p=0.044). Median MBL concentration was higher in patients who developed SIRS (p=0.048) but lower in those with post-operative infections (p=0.046). MBL-MASP-2 activities <100mU/ml protected from SIRS (p=0.007), low cardiac output syndrome (p=0.03) and multiorgan failure (p=0.012). In contrast, MBL2 YA/YA genotypes were associated with SIRS (p=0.018), low cardiac output syndrome (p=0.018), fever (p=0.018) and high inotropic score (VIS>30) (p=0.021). Thus, low MBL concentrations and associated genotypes may protect patients from systemic inflammation while high MBL serum levels and corresponding genotypes are risk factors of postoperative complications.

Frequent IgG subclass and mannose binding lectin deficiency in patients with chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a severe disease characterized by various symptoms of immune dysfunction. CFS onset is typically with an infection and many patients suffer from frequently recurrent viral or bacterial infections. Immunoglobulin and mannose binding lectin (MBL) deficiency are frequent causes for increased susceptibility to infections. In this study we retrospectively analysed 300 patients with CFS for immunoglobulin and MBL levels, and B-cell subset frequencies. 25% of the CFS patients had decreased serum levels of at least one antibody class or subclass with IgG3 and IgG4 subclass deficiencies as most common phenotypes. However, we found elevated immunoglobulin levels with an excess of IgM and IgG2 in particular in another 25% of patients. No major alteration in numbers of B cells and B-cell subsets was seen. Deficiency of MBL was found in 15% of the CFS patients in contrast to 6% in a historical control group. In a 2nd cohort of 168 patients similar frequencies of IgG subclass and MBL deficiency were found. Thus, humoral immune defects are frequent in CFS patients and are associated with infections of the respiratory tract.

Neutrophil functional disorder in childhood.

Neutrophil functional disorders thought to be uncommon, yet important as a cause of morbidity and mortality in infants and children. During the first years of life, when the immune system is still not completely mature, when the viral infections are frequent and antibiotic overuse can damage and alter the immune response, the inadequate nutrition followed with iron deficient anemia and malnutrition can lead the child`s organism in state of immunodeficiency. Sometimes is difficult to distinguish at the beginning weather the cause of patient suffering from frequent infections is existing of primary immunodeficiency disorder or the cause of the immunodeficiency state is just from exogenous factors. Fortunately, primary immune deficiencies are rare diseases and only 6-7% of all of them, due to the neutrophilic functional disorders. Unfortunately, many exogenous and environmental factors have influence to the immune system, and the percentage of secondary caused neutrophilic functional disorders is much higher and should be considered when children are investigated for immunodeficiency. So, when to suspect neutrophil functional disorder? The hallmarks for diseases related to the neutrophilic functional disorders are discussed in this article.

Mannose binding lectin and ficolin-2 polymorphisms are associated with increased risk for bacterial infections in children with B acute lymphoblastic leukemia.

BACKGROUND: We aimed to investigate whether the presence of mannose binding lectin (MBL2), ficolin 2 (FCN2) polymorphisms or the combined deficiency significantly influence the risk and subsequently the frequency of chemotherapy-induced bacterial infections in children with B acute lymphoblastic leukemia (B-ALL). PROCEDURE: MBL2 polymorphisms for exon 1 and FCN2 polymorphisms for promoter regions -986, -602, -557, -64, -4 and exon 8 regions +6,359, +6,424 were determined in children with B-ALL. FCN2 haplotype was determined by gene sequencing. Number and duration of FN episodes as well as number of bacterial infections were recorded during induction chemotherapy. RESULTS: Forty-four children with B-ALL (median age 4.3 years, 65.9% males) suffered from 142 FN episodes and 92 bacterial infections (40.2% Gram positive and 59.8% Gram negative). MBL2 low-risk genotype was found in 59.1%, medium-risk in 31.8% and high-risk in 9%. FCN2 low-risk haplotypes were detected in 38.2%, medium-risk in 44.1% and high-risk in 17.6%. MBL2 genotype and FCN2 haplotype were not associated with increased frequency of FN episodes. MBL2 medium/high-risk genotype and FCN2 medium/high-risk haplotype were associated with prolonged duration of FN (P = 0.007 and P = 0.001, respectively) and increased number of bacterial infections (P = 0.001 and P = 0.002, respectively). The combined MBL2/FCN2 medium/high-risk genotype was associated with an increased number of bacterial infections (P = 0.001). CONCLUSIONS: MBL2 and FCN2 single or combined deficiencies are associated with increased duration of FN episodes as well as increased number of bacterial infections in children with B-ALL suggesting a prognostic role of these genes.

Myeloperoxidase deficiency in mice exacerbates lung inflammation induced by nonviable Candida albicans.

OBJECTIVE: This study aimed to evaluate the effect of myeloperoxidase (MPO) deficiency on lung inflammation induced by nonviable Candida albicans (nCA). METHODS: Mice were inoculated intranasally with nCA, and accumulation of neutrophils and macrophages in the bronchoalveolar lavage fluid was analyzed by flow cytometry. The levels of macrophage inflammatory protein 2 (MIP-2), keratinocyte-derived chemokine (KC), tumor necrosis factor (TNF)-α, and interleukin (IL)-1ß in the lung were measured by ELISA. Production of MIP-2 and KC from neutrophils and macrophages was quantified in vitro. MIP-2 mRNA expression in the neutrophils was analyzed by real-time reverse transcription-PCR, and the extent of phosphorylation of ERK1/2 and Syk in the neutrophils was analyzed by Western blotting. RESULTS: The MPO(-/-) mice that received nCA showed more severe pneumonia than wild-type mice. Within 12 h of nCA administration, MPO(-/-) mice had significantly higher numbers of alveolar neutrophils and increased production of MIP-2 and KC relative to the responses seen in wild-type mice. Neutralization of MIP-2 and KC in vivo significantly reduced neutrophil infiltration. In vitro, production of MIP-2, but not that of KC, was enhanced in the nCA-stimulated neutrophils from MPO(-/-) mice, concomitant with up-regulation of Syk and ERK1/2. At 1 and 3 days after nCA administration, MPO(-/-) mice had significantly higher lung concentrations of TNF-α and IL-1ß than wild-type mice. CONCLUSION: Pulmonary administration of nCA produced an altered inflammatory response in MPO(-/-) mice relative to wild-type mice. Enhanced MIP-2 production by MPO(-/-) neutrophils may at least partly contribute to exacerbated inflammation in mutant mice.

Adiponectin deficiency suppresses lymphoma growth in mice by modulating NK cells, CD8 T cells, and myeloid-derived suppressor cells.

Previously, we found that adiponectin (APN) suppresses IL-2-induced NK cell activation by downregulating the expression of the IFN-γ-inducible TNF-related apoptosis-inducing ligand and Fas ligand. Although the antitumor function of APN has been reported in several types of solid tumors, with few controversial results, no lymphoma studies have been conducted. In this study, we assessed the role of APN in immune cell function, including NK cells, CTLs, and myeloid-derived suppressor cells, in EL4 and B16F10 tumor-bearing APN knockout (KO) mice. We observed attenuated EL4 growth in the APNKO mice. Increased numbers of splenic NK cells and splenic CTLs were identified under naive conditions and EL4-challenged conditions, respectively. In APNKO mice, splenic NK cells showed enhanced cytotoxicity with and without IL-2 stimulation. Additionally, there were decreased levels of myeloid-derived suppressor cell accumulation in the EL4-bearing APNKO mice. Enforced MHC class I expression on B16F10 cells led to attenuated growth of these tumors in APNKO mice. Thus, our results suggest that EL4 regression in APNKO mice is not only due to an enhanced antitumor immune response but also to a high level of MHC class I expression.

Long-term survival and late deaths after hematopoietic cell transplantation for primary immunodeficiency diseases and inborn errors of metabolism.

It is uncertain whether late mortality rates after hematopoietic cell transplantation for severe combined immunodeficiency (SCID), non-SCID primary immunodeficiency diseases (non-SCID PIDD), and inborn errors of metabolism (IEM) return to rates observed in the general population, matched for age, sex, and nationality. We studied patients with SCID (n = 201), non-SCID PIDD (n = 405), and IEM (n = 348) who survived for at least 2 years after transplantation with normal T cell function (SCID) or >95% donor chimerism (non-SCID PIDD and IEM). Importantly, mortality rate was significantly higher in these patients compared with the general population for several years after transplantation. The rate decreased toward the normal rate in patients with SCID and non-SCID PIDD beyond 6 years after transplantation, but not in patients with IEM. Active chronic graft-versus-host disease at 2 years was associated with increased risk of late mortality for all diseases (hazard ratio [HR], 1.87; P = .05). In addition, late mortality was higher in patients with non-SCID PIDD who received T cell-depleted grafts (HR 4.16; P = .007) and in patients with IEM who received unrelated donor grafts (HR, 2.72; P = .03) or mismatched related donor grafts (HR, 3.76; P = .01). The finding of higher mortality rates in these long-term survivors for many years after transplantation confirms the need for long-term surveillance.

Redundant contribution of myeloperoxidase-dependent systems to neutrophil-mediated killing of Escherichia coli.

Neutrophil microbicidal activity is a consequence of overlapping antimicrobial systems that vary in prominence according to the conditions of the neutrophil-microbe interaction, the nature of the microbe, and its metabolic state. In this study, normal, myeloperoxidase-deficient, and respiratory burst-deficient (chronic granulomatous disease [CGD]) neutrophils killed Escherichia coli with equivalent, high efficiencies. Killing by CGD and myeloperoxidase-deficient neutrophils was not augmented by supplements, such as exogenous H2O2 and myeloperoxidase, directed at ameliorating their metabolic defects, suggesting that nonoxidative microbicidal systems were sufficient for a full microbicidal effect. Neutrophils with an intact myeloperoxidase antimicrobial system (normal or appropriately supplemented deficient cells) were capable of rapidly suppressing E. coli DNA synthesis, while unsupplemented CGD or myeloperoxidase-deficient cells were far less effective, indicating that the myeloperoxidase system was active in normal neutrophils. The degree of DNA synthesis inhibition by myeloperoxidase-sufficient neutrophils could account, in a cell-free system, for most of the observed microbicidal activity. While the myeloperoxidase system was active and probably bactericidal, it was not rate limiting for microbicidal activity and appears to have been redundant with other microbicidal systems in the cell. Rapid and extensive inhibition of bacterial DNA synthesis appears to be an indicator of myeloperoxidase activity in neutrophils.

Bone marrow transplants in genetic diseases.

The first paper [9] advocating the displacement use of bone marrow transplantation (DBMT) to treat a variety of genetic metabolic diseases (including thalassaemia major) was put before a European Working Party in 1978. It evolved from mainly Westminster experience which showed the need [6] for DBMT and first successfully used donors other than matched siblings [9]. The principles of using DBMT to install a donor marrow as a component factory which can last a lifetime are outlined. It is not a panacea, being applicable to only about 7% of known inborn errors. Worthwhile correction of some 50 previously disabling diseases in over 700 patients has already been achieved worldwide and for most of the survivors no further treatment is used after 1 year. Guidelines for future extension, including gene transplants, are offered. The superior results of elective DBMT (about 95%) should encourage paediatricians to aim for earlier diagnoses and evaluations for transplants.