Advances in Immune Tolerance Induction in Enzyme Replacement Therapy

Inborn errors of metabolism (IEMs) are a group of genetic diseases that occur due to the either deficiency of an enzyme involved in a metabolic/biochemical pathway or other disturbances in the metabolic pathway including transport protein or activator protein deficiencies, cofactor deficiencies, organelle biogenesis, maturation or trafficking problems. These disorders are collectively significant due to their substantial impact on both the well-being and survival of affected individuals. In the quest for effective treatments, enzyme replacement therapy (ERT) has emerged as a viable strategy for patients with many of the lysosomal storage disorders (LSD) and enzyme substitution therapy in the rare form of the other inborn errors of metabolism including phenylketonuria and hypophosphatasia. However, a major challenge associated with enzyme infusion in patients with these disorders, mainly LSD, is the development of high antibody titres. Strategies focusing on immunomodulation have shown promise in inducing immune tolerance to ERT, leading to improved overall survival rates. The implementation of immunomodulation concurrent with ERT administration has also resulted in a decreased occurrence of IgG antibody development compared with cases treated solely with ERT. By incorporating the knowledge gained from current approaches and analysing the outcomes of immune tolerance induction (ITI) modalities from clinical and preclinical trials have demonstrated significant improvement in the efficacy of ERT. In this comprehensive review, the progress in ITI modalities is assessed, drawing insights from both clinical and preclinical trials. The focus is on evaluating the advancements in ITI within the context of IEM, specifically addressing LSDs managed through ERT.

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.

Negative selection on human genes underlying inborn errors depends on disease outcome and both the mode and mechanism of inheritance

Genetic variants underlying life-threatening diseases, being unlikely to be transmitted to the next generation, are gradually and selectively eliminated from the population through negative selection. We study the determinants of this evolutionary process in human genes underlying monogenic diseases by comparing various negative selection scores and an integrative approach, CoNeS, at 366 loci underlying inborn errors of immunity (IEI). We find that genes underlying autosomal dominant (AD) or X-linked IEI have stronger negative selection scores than those underlying autosomal recessive (AR) IEI, whose scores are not different from those of genes not known to be disease causing. Nevertheless, genes underlying AR IEI that are lethal before reproductive maturity with complete penetrance have stronger negative selection scores than other genes underlying AR IEI. We also show that genes underlying AD IEI by loss of function have stronger negative selection scores than genes underlying AD IEI by gain of function, while genes underlying AD IEI by haploinsufficiency are under stronger negative selection than other genes underlying AD IEI. These results are replicated in 1,140 genes underlying inborn errors of neurodevelopment. Finally, we propose a supervised classifier, SCoNeS, which predicts better than state-of-the-art approaches whether a gene is more likely to underlie an AD or AR disease. The clinical outcomes of monogenic inborn errors, together with their mode and mechanisms of inheritance, determine the levels of negative selection at their corresponding loci. Integrating scores of negative selection may facilitate the prioritization of candidate genes and variants in patients suspected to carry an inborn error.

Unexpected combination: DiGeorge syndrome and myeloperoxidase deficiency

We report a case of a 3-year-old boy who presented with recurrent bacterial and fungal infections and a known diagnosis of partial DiGeorge (22q11.2 deletion) syndrome. The nature and severity of his infections were more than normally expected in partial DiGeorge syndrome with normal T-cell counts and T-cell proliferative response to phytohaemagglutinin. This prompted further investigation of the immune system. An abnormal neutrophil respiratory oxidative burst, but normal protein expression of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system, led to the identification of myeloperoxidase deficiency. DiGeorge syndrome has a heterogeneous clinical phenotype and may not be an isolated diagnosis. It raises awareness of the possibility of two rare diseases occurring in a single patient and emphasises that even when a rare diagnosis is confirmed, if the clinical features remain atypical or unresponsive, then further investigation for additional cofactors is warranted.

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.

The liver is a metabolic and immunologic organ: A reconsideration of metabolic decompensation due to infection in inborn errors of metabolism (IEM)

Metabolic decompensation in inborn errors of metabolism (IEM) is characterized by a rapid deterioration in metabolic status leading to life-threatening biochemical perturbations (e.g. hypoglycemia, hyperammonemia, acidosis, organ failure). Infection is the major cause of metabolic decompensation in patients with IEM. We hypothesized that activation of the immune system during infection leads to further perturbations in end-organ metabolism resulting in increased morbidity. To address this, we established model systems of metabolic decompensation due to infection. Using these systems, we have described the pathologic mechanisms of metabolic decompensation as well as changes in hepatic metabolic reserve associated with infection. First and foremost, our studies have demonstrated that the liver experiences a significant local innate immune response during influenza infection that modulates hepatic metabolism. Based on these findings, we are the first to suggest that the role of the liver as a metabolic and immunologic organ is central in the pathophysiology of metabolic decompensation due to infection in IEM. The dual function of the liver as a major metabolic regulator and a lymphoid organ responsible for immunosurveillance places this organ at risk for hepatotoxicity. Mobilization of hepatic reserve and the regenerative capacity of a healthy liver compensates for this calculated risk. However, activation of the hepatic innate immune system may be deleterious in IEM. Based on this assertion, strategies aimed at modulating the innate immune response may be a viable target for intervention in the treatment of hepatic metabolic decompensation.

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.

Mannose-binding Lectin Deficiency in Patients with a History of Recurrent Infections

Mannose-binding lectin (MBL) is a protein of innate immune system that is involved in opsonization and complement activation. MBL deficiency is associated with predisposition to infectious diseases; however subnormal levels are also seen in healthy subjects. The aim of this study was to investigate the prevalence and clinical manifestation of MBL deficiency in patients with increased susceptibility to infection. We studied the MBL serum concentration of 104 patients with a history of recurrent and/or severe infections referred to Immunology, Asthma and Allergy Research Institute (IAARI) in order to evaluate the primary immunodeficiency (PID). The distribution of MBL deficiency in these patients and 593 healthy subjects of previous study were analyzed. The frequency of individuals with MBL deficiency was significantly higher in patients with recurrent and/or severe infections (13.5% [14/104]) compared with healthy subjects (4.7% [28/593]; p=0.001; OR 3.1, 95% CI 1.5-6.1). However, in 10.9% (7/64) of patients with recurrent infections without any immunodeficiency background, the MBL deficiency was detected. On the whole, our findings indicate an association between MBL deficiency and increased susceptibility to infections.

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.

Preliminary data on immunogenicity, safety and tolerability of trivalent inactivated influenza vaccine in children with inborn errors of metabolism at risk of decompensation

In order to evaluate the immunogenicity, safety and tolerability of influenza vaccination in children with inborn errors of metabolism (IEMs), we enrolled 20 patients with IEMs at risk of decompensation (14 males; mean age±SD, 8.5±3.9years) and 20 healthy age- and gender-matched controls. Four weeks after vaccination, seroconversion rates were 75-85% and seroprotection rates 85-95%, with high geometric mean titers (GMTs) of all three influenza antigen strains in both groups. Three months after vaccination, most of the subjects remained seroconverted with high seroprotection rates and high GMTs for all the three influenza strains. Safety and tolerability were also very good, with no differences between the groups.

Pericardial and abdominal fluid accumulation in congenital disorder of glycosylation type Ia

The association of fetal hydrops with Congenital Disorders of Glycosylation (CDG) has been reported previously. Pericardial fluid accumulation and ascites were also observed in a few young patients with CDG type Ia. Here we describe the clinical and biochemical features in three children developing life-threatening extravascular fluid accumulation. All patients carried severe PMM2 mutations comparable to the earlier reported patients with fetal hydrops. One patient was successfully treated with a pericardial-pleural shunt placement. Pericardial fluid accumulation and generalized oedema resolved temporarily in the other two children on regular albumin infusions and the use of diuretics. Sequential abdominal punctures were unsuccessful in the treatment of the extensive ascites production. The use of non-steroid anti-inflammatory agents and the application of high dose steroids had no clinical effect. Severe extravascular fluid accumulation progressed to decompensation and death. Biochemical investigations of the abdominal fluid and pericardial fluid demonstrated a high extracellular protein concentration, increased cytokine concentrations and an abnormal transferrin isoelectric focusing pattern characteristic of CDG type I. Our results are consistent with a local activation of the cytokine pathways and subsequent protein transport through the endothelial surface to the extravascular space. Normal glycosylation of cell surface proteins is essential for the normal fluid balance and protein transport through the pericardial and peritoneal membrane. Future therapeutic efforts should be directed to inhibit the abnormal immune response and excessive protein transport in this life-threatening complication of CDG syndrome.

Systemic lupus erythematosus-like disease in a 6-year-old boy with prolidase deficiency

This report describes the case of a boy with prolidase deficiency who presented with splenomegaly and leg ulcers. Laboratory examination revealed hypergammaglobulinaemia, hyperimmunoglobulinaemia E, increased erythrocyte sedimentation rate, elevated transaminases, positive antinuclear and anti-double-stranded DNA antibodies, and complement consumption. No haematological, renal or articular problems were detected; neutrophil count was normal. The skin lesions were thought to be of vasculitic origin, and a diagnosis of systemic lupus erythematosus was made although the requirements for diagnosis of systemic lupus erythematosus based on American Rheumatism Association criteria were not satisfied. The child was treated with immunosuppressive drugs with worsening of skin lesions before the diagnosis of prolidase deficiency. Prolidase deficiency and systemic lupus erythematosus share a number of common immunological features and at least three patients with prolidase deficiency and immunological and clinical findings fulfilling the diagnostic criteria for systemic lupus erythematosus of the American Rheumatism Association are reported in the literature. Here we review pathogenetic hypothesis linking the metabolic defect to the disturbance in immune function. In particular we discuss the role of highly increased rates of apoptosis and/or abnormal processing of apoptotic keratinocytes in prolidase deficiency and the role of C1q deficiency, which is associated with the failure of normal clearance of apoptotic cells bearing on their surfaces many of the autoantigens involved in systemic lupus erythematosus.

Immunizations for patients with metabolic disorders

Individuals with underlying metabolic disorders are a potential high-risk group for vaccine-preventable diseases. Newborn metabolic screening has provided a means of early identification and treatment for many of these disorders, whereas childhood immunization is one of the most effective means of decreasing the morbidity and mortality resulting from communicable diseases worldwide. There are very few contraindications to the routine administration of vaccines to the healthy, immunocompetent individual. In certain high-risk groups, such as immunocompromised patients, gravid females, and those with a history of previous anaphylactic reaction to a vaccine or its components, selective withholding of immunizations must be considered to decrease potential adverse events. A detailed analysis of the medical literature revealed few specific recommendations regarding appropriate immunization techniques for patients with metabolic disorders. In this review we detail the major metabolic disorder subtypes, elaborate on the available literature on immunizations for patients with these disorders, and provide suggested vaccine recommendations.

Immune function in children with classical phenylketonuria and tetrahydrobiopterin deficiencies

BACKGROUND

An increased susceptibility to infections has been observed in some patients with phenylketonuria (PKU), which is not well known whether it is due to alterations of plasma essential amino acid concentrations or to some other factors.

OBJECTIVE

This study is designed to establish B cell and T cell functions in 44 children with classical PKU and tetrahydrobiopterin (BH4) deficiencies and the effects of too high plasma phenylalanine (PA) concentrations (16.53 to 30.54 mg/dL) on the same parameters.

DESIGN

B and T cell functions of 33 children with classical PKU (divided into two groups based on fasting mean plasma PA concentrations: Group-I = 20.9 +/- 3.7 mg/dL, Group-II = 3.8 +/- 1.02 mg/dL), and 11 children with BH4 deficiencies (Group III) were studied. The results were compared between the groups and referenced with previously reported values from healthy controls.

RESULT

Delayed type skin hypersensitivity responses to purified protein derivative (PPD) in Group I and phytohaemagglutinin (PHA) in Group I, III were lower than the other groups and healthy controls. Plasma IgG and IgM concentrations of Group I was lower than the reference values. Although mean serum zinc and iron levels of all patients were lower than published values of healthy children, zinc and iron deficiencies in Group I, III were much more prominent as compared to Group II.

CONCLUSION

The somewhat low plasma IgG concentrations in Group I may be related to the very high plasma PA levels, however the role of zinc deficiency as a causal factor can not be ruled out. BH4 metabolism defects do not appear to affect the same parameters. Impaired delayed skin hypersensitivity responses in Group I and III can be explained by severe serum zinc deficiency. In the light of this study, we conclude that in order to establish a causal relationship between PKU and immune functions, further studies need to be conducted after the correction of micro-nutrient status of such children.

Carriers of the aspartylglucosaminuria genetic mutation and chronic arthritis

OBJECTIVE

To ascertain whether being a carrier of an autosomal recessive disease, aspartylglucosaminuria (AGU), predisposes to chronic arthritis, as does AGU disease.

METHODS

A group of 173 unrelated patients with rheumatoid arthritis (RA) but with no family members with AGU each gave a blood sample for AGUFin major mutation DNA analysis. A group of 131 AGU carriers who were parents of patients with AGU completed a questionnaire on joint symptoms and gave a blood sample for rheumatoid factor (RF) analysis. Eight RF positive parents with prolonged joint symptoms had a rheumatological evaluation.

RESULTS

Six patients (1/28) with RA were carriers of the AGUFin major mutation, whereas the carrier frequency among Finns in general is 1/50 to 1/85. Three AGU carriers had chronic arthritis (2.3%), and 17 (13%) were RF positive; the respective percentages among Finns in general are 1.4% and 5%.

CONCLUSION

As for AGU disease, carrier status may also predispose to chronic arthritis.

Simple PCR detection of haptoglobin gene deletion in anhaptoglobinemic patients with antihaptoglobin antibody that causes anaphylactic transfusion reactions

Two anhaptoglobinemic patients showing anaphylactic transfusion reactions by antihaptoglobin antibody were found. Southern blot analysis indicated that 2 patients were homozygous for the deleted allele of the haptoglobin gene (Hp(del)) as reported previously. We have identified the junction region of the deletion from genomic DNA of 1 patient using cassette-mediated polymerase chain reaction (PCR). Then, the deleted region from the 5' breakpoint to the promoter region of the Hp was amplified from genomic DNA of a control individual using PCR. DNA sequence analysis of these regions indicated that the 5' breakpoint of the Hp(del) allele was located 5. 2 kilobase (kb) upstream of exon 1 of the Hp and the 3' breakpoint was positioned between 52 and 53 base pair (bp) upstream of exon 5 of the haptoglobin-related gene. There was no significant homology between the DNA sequences flanking the 5' and 3' breakpoints, except for a 2-bp (TG) identity. To examine the gene frequency, we have developed a simple PCR method to detect the gene deletion. We found 8, 16, and 17 Hp(del) alleles in 157 Koreans, 523 Japanese, and in 284 Chinese, respectively, but did not find the Hp(del) in 101 Africans or in 100 European-Africans. The incidence of individuals homozygous for the Hp(del) allele was therefore expected to be 1/4000 in Japanese, 1/1500 in Koreans, and 1/1000 in Chinese. This incidence is higher than that of IgA deficiency in Japanese. More attention should be paid on haptoglobin deficiency and antihaptoglobin antibody as the cause of transfusion-related anaphylactic reactions in Asian populations. (Blood. 2000;95:1138-1143)

Infectious complications of propionic acidemia in Saudia Arabia

A retrospective study of 38 patients with propionic acidemia indicates a high frequency of infections; affecting 80% of such patients. The Saudi Arabian population studied is a product of consanguineous marriages, and presents with a severe phenotype. Most microorganisms implicated are unusual, which suggests an underlying immune deficiency. These frequent infections occur despite aggressive treatment with appropriate diets, carnitine and during acute episodes of the disease with metronidazole, which suggests a global effect of the disease on T and B lymphocytes as well as on the bone marrow cells. Any patient with propionic acidemia should be closely followed up for an intercurrent infection in association with acute metabolic decompensation.

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.

Immunodeficiency as a component of recognizable syndromes

Immunodeficiency occurs in numerous genetic syndromes. While it is the dominant manifestation in primary immunodeficiencies, immune deficits may also be seen in a variety of other recognizable syndromes. Immunodeficiency has been reported in 64 such conditions, adding to the 45 recognized primary immunodeficiencies. These uncommon syndromes with immune defects can present with: (a) growth deficiency (11 syndromes with disproportionate or proportionate short stature), (b) specific organ system dysfunction (18 with gastrointestinal, dermatologic, or neurologic abnormalities), (c) inborn errors of metabolism (13), (d) miscellaneous anomalies (10), or (e) chromosome anomalies (12). In most of the disorders, only some of the affected patients have immune defects. However, in 27 syndromes, immunodeficiency is a constant finding. We briefly review the clinical manifestations of each syndrome and delineate the specific associated immune defects. In most syndromes, the connection between the immune and other defects is unknown. Recognition of these conditions involving both the immune and other organ systems may facilitate accurate diagnosis and management as well as yield information regarding genes critical for the development of the involved systems.

Erythrophagocytosis by cultured skin fibroblasts from patients with hereditary metabolic disorders

Phagocytosis of native allogenic red blood cells was observed in cultures of skin fibroblasts obtained from patients with neuronal ceroid-lipofuscinosis, Niemann-Pick disease type C and morbus Fabry. Occasional phagocytizing cells were observed in 9 other syndromes. Cells from three normal donors did not phagocytize.

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.

Immune regulation: what immunodeficiency disease has taught us

"Immune regulation: what immunodeficiency disease has taught us" is reviewed by discussing three immuno-deficiency disorders. Hypogammaglobulinemia, the first documented primary immunodeficiency disorder, has a well defined and uniform clinical presentation which reflects a variety of underlying abnormalities involving the B cell, T cell, and monocyte. X-linked hypogammaglobulinemia, transient hypogammaglobulinemia of infancy common variable immunodeficiency, and their pathogenesis are discussed. Combined immunodeficiency with adenosine deaminase (ADA) deficiency first led to the now accepted concept that a biochemical abnormality may result in immunodeficiency. The clinical presentation, possible biochemical abnormalities resulting in the observed immunodeficiency, relative selectivity of the defect for the immune system, and potential applications of knowledge gained from the study of ADA deficiency are presented. Acquired immunodeficiency (AIDS) has resulted in the concept that a virus is cytopathic for a specific population of T cells and that this, at least in part, results in the immunodeficiency seen in AIDS.

The LFA-1, Mac-1 glycoprotein family and its deficiency in an inherited disease

A family of functionally important, high-molecular-weight glycoproteins with identical beta subunits has recently been defined on leukocyte cell surfaces. Soon after these molecules and at least some of their functions had been defined with monoclonal antibodies, an inherited disease, LFA-1, Mac-1 deficiency, was discovered in humans. This deficiency has confirmed that this glycoprotein family is of central importance in leukocyte cell surface adhesion reactions.

[A case of macroamylasemia]

An observed case of macroamylasaemia is presented with a description of the identification technique employed. As in cases reported in the literature, antiglobulin sera did not precipitate the complexes. This would appear to exclude the possibility of the immunity-related aetiopathogenesis the patient's immunological and electrophoretic patterns suggested.

Avian riboflavinuria--XI. Immunological quantitation of cross-reacting liver proteins from normal, heterozygous, and mutant hens

A genetic defect, avian riboflavinuria, was discovered in a strain of Single Comb White Leghorn chickens and has been attributed to the absence of functional riboflavin-binding protein (RBP). The ratio of functional RBP in blood, egg yolk, and egg white was 2 (RdRd) : 1 (Rdrd) : 0 (rdrd). The present study on non-riboflavin-binding, cross-reacting proteins (CRPs) from RdRd, Rdrd, and rdrd hens involved partial purification and immunochemical quantitation using antiserum to RBP. Immunoreactivities (microgram/g liver) of CRPs were found to be 2.6 (RdRd) : 1.3 (Rdrd) : 0.02 (rdrd). Reciprocal cross-reactions were observed with rabbit sera directed toward both RdRd CRP and RBP. Reaction of the CRPs with antiglycopeptide serum (specific for beta-linked galactose) showed that they were glycosylated. CRPs from RdRd and Rdrd hens had relative antigenicities similar to that of RBP (Krel approximately or equal to 1), while rdrd CRP had a significantly lower antigenicity (Krel = 0.003). The molecular weights of the CRPs as determined by SDS-polyacrylamide gel electrophoresis were as follows: RdRd = 31,6000, Rdrd = 30,900, and rdrd = 27,500. The molecular weight of egg yolk RBP was 34,7000 by the same method. The conclusion is drawn that the rd gene codes for a nonfunctional mutant protein, possibly an "altered precursor", that is different from RBP.

Immunological investigation in adenine phosphoribosyl transferase (APRT) deficiency

In a family with partial or total adenine phosphoribosyl transferase (APRT) deficiency, T and B cell function was evaluated by counting rosette-forming cells, by investigating lymphocyte transformation to phytohaemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM), by assaying serum immunoglobulins and determining lymphocyte membrane immunoglobulins by immunofluorescence. Delayed cutaneous hypersensitivity was also assayed. The absence of gross immunological deficiency in the homozygotes, as well as in the heterozygotes, suggests that the APRT-mediated pathway of purine metabolism is relatively unimportant for lymphocyte function.

[Immunodeficiencies and enzyme deficiencies]

The first part of the paper outlines the actual situation of the recent investigations on the interpretative problem of the immunological deficits combined with enzymatic deficits. ADA deficit associated with combined immunodeficiency is an autosomal recessive form. Low enzyme levels, which is produced by a structural gene located on chromosome 20, were detected in chronic lymphatic leukemias where ADA decrease is correlated to low levels of T lymphocytes and the prevalence of an atypical B lymphocyte population. Particularly high levels of ADA were detected in acute lymphoblastic leukemias, in transplant rejection, in blastic crisis of chronic myeloid leukemia... NP deficit is associated with a T branch immunodeficiency, with high levels of inosine, guanosine, hypouricemia, hypochromic microcythemia and hematopoietic tissue megaloblastosis. This enzyme, with trimeric structure, whose structural gene is located on chromosome 14, shows a cytoplasmic location, and its maximum activity is to be found in T lymphocytes separated by rosetting. IGPT deficit is to be held responsible for the neurological Lesch-Nyhan syndrome. This deficit is associated with a depression of B lymphocyte function evaluated as response to the mitogens (PWM, Protein A) or as specific immunoglobulins production. At last the Authors report some personal investigations performed on hemolysates and lymphocytes of subjects with impaired immunity, as well as on some children at birth to establish the correlation between ADA and NP behaviour and immunosurveillance. Lastly, the data on the variations of the enzymatic and immunological parameters of subjects with immunodeficiency associated to enzymopenia after red cell transfusion are reported.

Nucleoside-phosphorylase deficiency in a child with severely defective T-cell immunity and normal B-cell immunity

A 5-year-old girl with a history of recurrent infection and anaemia has no measurable purine nucleoside phosphorylase (N.P.) activity in her red blood-cells. Her serum-immunoglobulin levels are normal, as are her antibody responses to thymus dependent and independent antigens. However, she has severe lymphopenia, pronounced depression of lymphocyte response to mitogenic and allogeneic cell stimuli, and greatly decreased T-cell rosette formation. Her parents are second cousins; their red cells contain less than half the normal level of N.P. activity. They also share an unusual N.P. isozyme pattern indicative of molecular hybridisation between catalytically active and inactive subunits, which strongly supports the assumption that they are heterozygous and their daughter is homozygous for a "silent" allele at the N.P. gene locus. Inherited deficiency of adenosine deaminase, an enzyme catalysing a reaction only one metabolic step away from that of N.P., is known to cause immunodeficiency. It is therefore very likely that this patient's lack of demonstrable N.P. activity is responsible for her syndrome.

[Alpha-antitrypsin deficiency in infancy]

Clinical, histological (including electron-microscopic), immunohistochemical and genetic studies were performed on two infants with alpha1-antitrypsin deficiency. The clinical picture was one of neonatal biliary stasis. Liver biopsies revealed multiple cytoplasmic acidophilic bodies within many cells of the liver parenchyma which were strongly periodic acid-Schiff-positive, diastase-resistant and stained selectively with fluorescein-labelled rabbit antihuman alpha1-antitrypsin. Ultrastructurally, the bodies were situated within enlarged cisterns of the endoplasmatic reticulum. Both infants were of the protease inhibitor (Pi) phenotype ZZ, having inherited on PiZ gene from each parent. Results of Pi typing of both families were consistent with an autosomal co-dominant inheritance. Both infants are clinically well except for slight hepatomegaly at one year of age. But transaminase and gamma-glutamyl transpeptidase activities have remained elevated.