Immunoglobulin E deficiency in ataxia-telangiectasia

Increased Hazard Risk of First Malignancy in Adults with Undetectable Serum IgE: a Retrospective Cohort Study

PURPOSE

The clinical relevance of IgE-deficiency is not established. Previous studies have postulated a relationship between absent serum IgE and the incidence of specific malignancies. We sought to examine the relationship between undetectable total serum IgE (< 3 IU/mL) and first malignancy, considering both general all-cause malignancy risk and risk of specific malignancy subtypes in adult subjects.

METHODS

Retrospective cohort study at a single center of 39,965 adults aged 18 or older (median age 51, 65.1% female) with at least one serum total IgE measurement from 1998 to 2020. Analytics included chi² table and logistic regression modeling of the main outcome measures, which include diagnosis of first malignancy and first diagnosis of specific malignancy subtype.

RESULTS

Of the entire cohort, 2584 subjects (6.5%) developed a first malignancy and 2516 (6.3%) had an undetectable IgE. Of those with undetectable IgE levels, 8.9% developed a first malignancy versus 6.3% with detectable IgE measurements. After adjusting for risk factors, there was a significant association between undetectable IgE and risk/hazard of first malignancy (relative risk 1.49, 95% confidence interval (CI) 1.27-1.75) (hazard ratio 1.28, 95% CI 1.08-1.52). Results were similar in multiple sensitivity analyses. For type of malignancy developed, undetectable IgE was associated with increased risk of hematologic malignancy (relative risk 2.07, 95% CI 1.29-3.30) and skin malignancy (relative risk 1.52, 95% CI 1.13-2.05).

CONCLUSION

Compared to individuals with detectable IgE levels, patients with undetectable total serum IgE had increased risk and hazard of first malignancy in general, and increased risk of hematologic malignancy in particular.

The natural history of ataxia-telangiectasia (A-T): A systematic review

BACKGROUND

Ataxia-telangiectasia is an autosomal recessive, multi-system, and life-shortening disease caused by mutations in the ataxia-telangiectasia mutated gene. Although widely reported, there are no studies that give a comprehensive picture of this intriguing condition.

OBJECTIVES

Understand the natural history of ataxia-telangiectasia (A-T), as reported in scientific literature.

SEARCH METHODS

107 search terms were identified and divided into 17 searches. Each search was performed in PubMed, Ovid SP (MEDLINE) 1946-present, OVID EMBASE 1980 -present, Web of Science core collection, Elsevier Scopus, and Cochrane Library.

SELECTION CRITERIA

All human studies that report any aspect of A-T.

DATA COLLECTION AND ANALYSIS

Search results were de-duplicated, data extracted (including author, publication year, country of origin, study design, population, participant characteristics, and clinical features). Quality of case-control and cohort studies was assessed by the Newcastle-Ottawa tool. Findings are reported descriptively and where possible data collated to report median (interquartile range, range) of outcomes of interest.

MAIN RESULTS

1314 cases reported 2134 presenting symptoms. The most common presenting symptom was abnormal gait (1160 cases; 188 studies) followed by recurrent infections in classical ataxia-telangiectasia and movement disorders in variant ataxia-telangiectasia. 687 cases reported 752 causes of death among which malignancy was the most frequently reported cause. Median (IQR, range) age of death (n = 294) was 14 years 0 months (10 years 0 months to 23 years 3 months, 1 year 3 months to 76 years 0 months).

CONCLUSIONS

This review demonstrates the multi-system involvement in A-T, confirms that neurological symptoms are the most frequent presenting features in classical A-T but variants have diverse manifestations. We found that most individuals with A-T have life limited to teenage or early adulthood. Predominance of case reports, and case series demonstrate the lack of robust evidence to determine the natural history of A-T. We recommend population-based studies to fill this evidence gap.

A Critical Review on the Standardization and Quality Assessment of Nonfunctional Laboratory Tests Frequently Used to Identify Inborn Errors of Immunity

Inborn errors of immunity (IEI), which were previously termed primary immunodeficiency diseases, represent a large and growing heterogeneous group of diseases that are mostly monogenic. In addition to increased susceptibility to infections, other clinical phenotypes have recently been associated with IEI, such as autoimmune disorders, severe allergies, autoinflammatory disorders, benign lymphoproliferative diseases, and malignant manifestations. The IUIS 2019 classification comprises 430 distinct defects that, although rare individually, represent a group affecting a significant number of patients, with an overall prevalence of 1:1,200-2,000 in the general population. Early IEI diagnosis is critical for appropriate therapy and genetic counseling, however, this process is deeply dependent on accurate laboratory tests. Despite the striking importance of laboratory data for clinical immunologists, several IEI-relevant immunoassays still lack standardization, including standardized protocols, reference materials, and external quality assessment programs. Moreover, well-established reference values mostly remain to be determined, especially for early ages, when the most severe conditions manifest and diagnosis is critical for patient survival. In this article, we intend to approach the issue of standardization and quality control of the nonfunctional diagnostic tests used for IEI, focusing on those frequently utilized in clinical practice. Herein, we will focus on discussing the issues of nonfunctional immunoassays (flow cytometry, enzyme-linked immunosorbent assays, and turbidimetry/nephelometry, among others), as defined by the pure quantification of proteins or cell subsets without cell activation or cell culture-based methods.

The other side of the coin: IgE deficiency, a susceptibility factor for malignancy occurrence

Since the discovery of IgE, almost all attention was given to conditions with elevated specific or total IgE levels such as atopy, type I hypersensitivity reactions, or parasitic infestations. Recent prospective and retrospective studies show that having very low IgE levels, such as those seen in IgE deficiency (IgE<2.5 kU/L), is not without clinical consequences. Patients with ultra-low IgE levels have an elevated risk of cancer of any type. These results are in agreement with murine models research which demonstrated that grafted tumors grow faster and bigger on an IgE knockout background. The novel finding that IgE deficiency is a susceptibility factor for cancer, fits very well with the AllergoOncology concept. The reports on a beneficial, cytotoxic function of IgE, in cooperation with its high (FcεRI) and low (FcεRII, CD23) affinity IgE receptors resulting in tumor cell phagocytosis, propose a role of IgE in cancer surveillance. It appears that not only deficiency of serum IgE, but also lack of tissue-bound IgE is important in malignancy susceptibility in these patients. As such, IgE deficient individuals with absent serum and cell-bound IgE as suggested by negative type I hypersensitivity skin tests, are at the highest risk for a malignancy diagnosis. In contrast, IgE deficient individuals with cell-bound IgE depicted through positive type I hypersensitivity skin tests, have lower rates of malignancy diagnosis. The present report discusses the evidence and potential role of ultra-low IgE as a novel biomarker for cancer susceptibility.

Warts and all: human papillomavirus in primary immunodeficiencies

Infection with human papillomavirus (HPV) is almost universal and eventually asymptomatic, but pathologic infection with HPV is severe, recurrent, and recalcitrant to therapy. It is also an underappreciated manifestation of primary immunodeficiency. Mutations in EVER1, EVER2, GATA2, CXCR4, and dedicator of cytokinesis 8 (DOCK8) are typically associated with extensive HPV infections, whereas several other primary immune defects result in severe HPV much less frequently. We review immunodeficiencies with severe HPV infections and the mechanisms underlying them.

Immunodeficiency, radiosensitivity, and the XCIND syndrome

Through the analysis of a rare disorder called ataxia-telangiectasia (A-T), many important biological lessons have been gleaned. Today, it is clear that the underlying defect of A-T lies in the nucleus, as an inability to repair or process double strand breaks. More important, by the A-T phenotype now allows us to appreciate a much more general distinction between immunodeficiencies that are radiosensitive and those that are not.

IgE, CD8(+)CD60+ T cells and IFN-alpha in human immunity to parvovirus B19 in selective IgA deficiency

Although IgE is implicated in viral immunity, its role in parvovirus B19 immunity and its relationship to other immunological states has not been studied. Total serum immunoglobulin levels, IgG and IgE anti-parvovirus B19, blood lymphocyte numbers, and epsilon and cytokine specific mRNA were determined in pediatric patients with normal serum IgA levels (IgA+) and selective IgA deficiency (IgA-) on days 0 (initial diagnosis) and 14, and 3 years after recovery (nephelometry, Western blot test, flow cytometry, reverse transcriptase-polymerase chain reaction). We found that both patients had serum IgM, IgG, IgE, and IgA levels within normal ranges on day 0 to 3 years, excluding IgG(1) and IgA in the IgA- patient, which were elevated and negative, respectively, and IgE in the IgA+ patient, which was elevated (>100 IU/ml). The serum IgA+ and IgA- patients made IgE (and IgG) anti-parvovirus B19 at all time points. Excluding CD8(+)CD60+ T cells, determinations of T, B, and NK lymphocyte subsets always were within normal ranges. In both patients, CD8(+)CD60+ T-cell numbers were within normal ranges on day 0, but dramatically increased on day 14 (more than fivefold). At 3 years, they had returned to normal in the IgA+ patient, but remained high in the IgA- patient. On day 0 to 3 years, peripheral blood mononuclear cells of both patients expressed epsilon- and interferon (IFN)-alpha-specific mRNA. On day 0, the IgA+ patient expressed interleukin (IL)-4 and IL-10, but not IL-2, IFN-gamma, or IL-6 mRNA; the IgA- patient expressed IL-6 and IL-10 mRNA, but not IL-4, IL-2, or IFN-gamma mRNA. At 3 years, the IgA+ patient expressed mRNA for all cytokines, but the IgA- patient did not express mRNA for any of these cytokines. Our results suggest that IgE is important in parvovirus B19 immunity, and that IFN-alpha and CD8(+)CD60+ T cells may regulate IgE memory responses and isotype switching.

Immunoglobulin class switch recombination is impaired in Atm-deficient mice

Immunoglobulin class switch recombination (Ig CSR) involves DNA double strand breaks (DSBs) at recombining switch regions and repair of these breaks by nonhomologous end-joining. Because the protein kinase ataxia telengiectasia (AT) mutated (ATM) plays a critical role in DSB repair and AT patients show abnormalities of Ig isotype expression, we assessed the role of ATM in CSR by examining ATM-deficient mice. In response to T cell–dependent antigen (Ag), Atm^−/− mice secreted substantially less Ag-specific IgA, IgG1, IgG2b, and IgG3, and less total IgE than Atm^+/+ controls. To determine whether Atm^−/− B cells have an intrinsic defect in their ability to undergo CSR, we analyzed in vitro responses of purified B cells. Atm^−/− cells secreted substantially less IgA, IgG1, IgG2a, IgG3, and IgE than wild-type (WT) controls in response to stimulation with lipopolysaccharide, CD40 ligand, or anti-IgD plus appropriate cytokines. Molecular analysis of in vitro responses indicated that WT and Atm^−/− B cells produced equivalent amounts of germline IgG1 and IgE transcripts, whereas Atm^−/− B cells produced markedly reduced productive IgG1 and IgE transcripts. The reduction in isotype switching by Atm^−/− B cells occurs at the level of genomic DNA recombination as measured by digestion–circularization PCR. Analysis of sequences at CSR sites indicated that there is greater microhomology at the μ–γ1 switch junctions in ATM B cells than in wild-type B cells, suggesting that ATM function affects the need or preference for sequence homology in the CSR process. These findings suggest a role of ATM in DNA DSB recognition and/or repair during CSR.

Immunodeficiency and infections in ataxia-telangiectasia

OBJECTIVE

To characterize the immunodeficiency in ataxia-telangiectasia (A-T) and to determine whether the immunodeficiency is progressive and associated with increased susceptibility to infections.

STUDY DESIGN

Records of 100 consecutive patients with A-T from the Johns Hopkins Ataxia-Telangiectasia Clinical Center (ATCC) were reviewed.

RESULTS

Immunoglobulin (Ig) deficiencies are common, affecting IgG4 in 65% of patients, IgA in 63%, IgG2 in 48%, IgE in 23%, and IgG in 18%. Lymphopenia affected 71% of patients, with reduced B-lymphocyte number in 75%, CD4 T lymphocytes in 69%, and CD8 T lymphocytes in 51%. There was no trend for increased frequency or severity of immune abnormalities with age. Recurrent upper and lower respiratory tract infections were frequent: otitis media in 46% of patients, sinusitis in 27%, bronchitis in 19%, and pneumonia in 15%. Sepsis occurred in 5 patients, in 2 patients concurrent with cancer chemotherapy. Warts affected 17% of patients, herpes simplex 8%, molluscum contagiosum 5%, candidal esophagitis 3%, and herpes zoster 2%. Uncomplicated varicella infection occurred in 44% of patients; 2 patients had more than one clinical episode. No patient had Pneumocystis jerovici pneumonia or a complication of live viral vaccine.

CONCLUSIONS

In spite of the high prevalence of laboratory immunologic abnormalities, systemic bacterial, severe viral, and opportunistic infections are uncommon in A-T. Cross-sectional analysis suggests that the immune defect is rarely progressive.

Neurocutaneous disorders

"Neurocutaneous disorders" is a catch-all phrase that includes all disorders involving both the nervous systems and the skin. These may range from disorders in which cutaneous findings are essential to diagnosis to those with less significant involvement of the skin. Because of the variety of disorders that involve the skin and the nervous system, this article reviews a few of the more essential diagnoses, and those with recent advancements in diagnosis and management. Many of these diseases are single gene disorders, for which the genes have been discovered in the past few years. The article is divided into sections, highlighting disorders transmitted by different inheritance pattern.

Oligo-/monoclonal gammopathy and hypergammaglobulinemia in ataxia-telangiectasia. A study of 90 patients

We investigated the presence of hypergammaglobulinemia and oligo-/monoclonal gammopathy in 90 patients (from 80 families) with ataxia-telangiectasia ranging in age from 2 to 29 years. Of the 90 patients, 38.8% displayed hypergammaglobulinemia. An isolated increase in IgM was the most common finding (23.3%) followed by a simultaneous increase in IgM and IgG (8.8%), an isolated increase in IgA (3.3%), an elevated level of IgG (2.2%) and a concomitant increase in IgM and IgA (1.1%), respectively. Seven of the patients (8.1%) had oligo-/monoclonal gammopathy. The gammopathies included all major immunoglobulin isotypes. Chemotherapeutic intervention in 2 cases precipitated the emergence of new clones within a matter of weeks. Further investigation of oligo-/monoclonal gammopathies in these patients may lead to a clearer understanding of the clinical course and provide further insight into the underlying mechanisms of B-cell abnormalities in ataxia-telangiectasia.

Impaired IgG antibody production to pneumococcal polysaccharides in patients with ataxia-telangiectasia

Various factors seem to be etiologic in the susceptibility to sinopulmonary infections in ataxia-telangiectasia (A-T) patients, i.e., low serum and salivary IgA, low serum IgG2, and even aspiration of saliva. S. pneumoniae is a common pathogen responsible from pulmonary infections and impaired antibody response to polysaccharide antigens is seen in patients with IgG2 and IgA deficiency as well as patients with CVID and WAS. We studied IgG-type antibody production to six pneumococcal serotypes in 29 A-T patients by ELISA before and 3-4 weeks after pneumococcal vaccine. The response was considered positive when the antibody titer was >10 U/ml but weak when the titer was 10-20 U/ml. Twenty-two of 29 (76%) patients did not respond to any of the serotypes, 5 (17%) showed a positive response to one serotype, 1 (3.4%) to two serotypes, and 1 (3.4%) to four serotypes. With conversion to gravimetric units (ng IgG/ml) and >1800 ng/ml (300 ng Ab N/ml) considered a positive response, 5 of 29 (17.2%) patients showed a positive response (300 ng ab N/ml) to two or fewer serotypes. All patients tested produced IgG antibody to tetanus toxoid. Sixteen of 27 (59.3%) patients had low IgG2 and four (14.8%) had low IgG3 levels, while 18 (62.1%) of 29 patients had low serum IgA. No correlation was found either between serum Ig isotype levels and antipolysaccharide antibody response or between susceptibility to infection and antibody production. The mechanism responsible for disturbed antipolysaccharide (TI-2 antigen) antibody production in patients with A-T needs to be investigated. It may provide additional information on the function of the ATM gene product and be helpful in clarifying the role of B cells and contribution of T cells in TI-2 responses.

ATM binds to beta-adaptin in cytoplasmic vesicles

Inherited mutations in the ATM gene lead to a complex clinical phenotype characterized by neuronal degeneration, oculocutaneous telangiectasias, immune dysfunction, and cancer predisposition. Using the yeast two-hybrid system, we demonstrate that ataxia telangiectasia mutated (ATM) binds to beta-adaptin, one of the components of the AP-2 adaptor complex, which is involved in clathrin-mediated endocytosis of receptors. The interaction between ATM and beta-adaptin was confirmed in vitro, and coimmunoprecipitation and colocalization studies show that the proteins also associate in vivo. ATM also interacts in vitro with beta-NAP, a neuronal-specific beta-adaptin homolog that was identified as an autoantigen in a patient with cerebellar degeneration. Our data describing the association of ATM with beta-adaptin in vesicles indicate that ATM may play a role in intracellular vesicle and/or protein transport mechanisms.

Defective signaling through the B cell antigen receptor in Epstein-Barr virus-transformed ataxia-telangiectasia cells

A characteristic series of immunological abnormalities are observed in the human genetic disorder ataxia-telangiectasia (A-T). The recent cloning of a gene mutated in this syndrome provides additional evidence for a defect in intracellular signaling in A-T. We have investigated the possibility that signaling through the B cell antigen receptor is one manifestation of the A-T defect. In response to cross-linking of the B cell receptor, several A-T cell lines were defective in their mitogenic response; in addition Ca2+ mobilization from internal stores was either absent or considerably reduced in these cell lines in response to cross-linking. The defect in signaling was not due to difference in expression of surface immunoglobulin. The defective response in A-T cells was also evident in several arms of the intracellular cascade activated by B cell cross-linking. Tyrosine phosphorylation of phospholipase Cgamma1, a key step in activation of the enzyme, was reduced or negligible in some A-T cell lines. This defect in signaling was also seen at the level of Lyn tyrosine kinase activation and its association with and activation of phosphatidylinositol 3-kinase. Our results provide evidence for a role for the ATM gene product in intracellular signaling which may account at least in part for the abnormalities in B cell function in A-T.

The genetic defect in ataxia-telangiectasia

The autosomal recessive human disorder ataxia-telangiectasia (A-T) was first described as a separate disease entity 40 years ago. It is a multisystem disease characterized by progressive cerebellar ataxia, oculocutaneous telangiectasia, radiosensitivity, predisposition to lymphoid malignancies and immunodeficiency, with defects in both cellular and humoral immunity. The pleiotropic nature of the clinical and cellular phenotype suggests that the gene product involved is important in maintaining stability of the genome but also plays a more general role in signal transduction. The chromosomal instability and radiosensitivity so characteristic of this disease appear to be related to defective activation of cell cycle checkpoints. Greater insight into the nature of the defect in A-T has been provided by the recent identification, by positional cloning, of the responsible gene, ATM. The ATM gene is related to a family of genes involved in cellular responses to DNA damage and/or cell cycle control. These genes encode large proteins containing a phosphatidylinositol 3-kinase domain, some of which have protein kinase activity. The mutations causing A-T completely inactivate or eliminate the ATM protein. This protein has been detected and localized to different subcellular compartments.

An early-onset recessive cerebellar disorder with distal amyotrophy and, in two patients, gross myoclonia: a probable ataxia telangiectasia variant

We report a family of 4 siblings from a non-consanguineous marriage, presenting with an early onset recessive cerebellar ataxia and progressive distal limb wasting. Ocular or other telangiectasias were absent. There were neither frequent infections nor immunodeficiencies. The two youngest patients exhibited an incapacitating myoclonus which abated markedly after 20 years. Late onset diabetes was demonstrated in 3 patients. Hypogonadism was not a feature and there was a prolonged survival in the 4 patients. The oldest sibling died of a pancreatic adenocarcinoma. alpha-Fetoprotein was elevated with normal carcinoembryonic antigen values in three patients. Cytogenetic analysis and radioresistant DNA synthesis was compatible with the diagnosis of ataxia-telagiectasia. This family probably represents a rare variant of ataxia-telangiectasia.

Atypical clinical presentation of ataxia telangiectasia

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by progressive cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency with recurrent infections, IgA and IgE deficiency, and increased incidence of malignancies. The pathognomonic biological abnormalities consist of spontaneous chromosomal instability resulting in a high in vivo occurrence of cells with translocations, especially involving chromosomes 7 and 14, and a relative insensitivity of DNA replication in vitro to radiation exposure. We report on a patient with the biological hallmarks of AT but with atypical clinical manifestations. Although progressive cerebellar ataxia was present, the neurological picture was broader than that usually seen in AT and included peripheral polyneuropathy and spinal atrophy. On the other hand, telangiectasias, recurrent infections, malignancies, IgA deficiency, or other immunological abnormalities were not present. This illustrates that the clinical picture of AT is broad and nonspecific, and highlights the diagnostic value of cytogenetic analysis and studies of radioresistance of DNA synthesis.

Familial IgE deficiency associated with sinopulmonary disease

Three generations of relatives of 58-year-old nonidentical twins with chronic bronchitis and fibrotic lung disease were evaluated. Sera of 23 family members, 14 with a history of excessive sinopulmonary infections, were examined for deficiencies of immunoglobulin classes, IgG subclasses, and specific antibody to tetanus toxoid and Hemophilus influenzae type b. Of 14 symptomatic family members, 12 had serum IgE concentrations less than 5 IU/ml. Four had values less than 1 IU/ml. Serum IgE was greater than 10 IU/ml in all nine asymptomatic individuals. Inheritance of low IgE appeared to be autosomal dominant, with variable penetrance. IgA was low normal (70-90 mg/dl) in three individuals. Two of these were IgE deficient. One symptomatic child had unmeasurable IgG2 (less than 10 mg/dl) and IgE (less than 0.5 IU/ml). This kindred demonstrates that IgE deficiency can be familial, and associated with sinopulmonary disease.

Abnormality in DNA-protein binding in ataxia-telangiectasia nuclear extracts

Anomalies in DNA replication, repair and recombination in ataxia-telangiectasia (A-T) point to a defect in structure or function of chromatin. In this study we have compared DNA-protein binding in nuclear extracts from control and A-T cells using two assay systems, filter-binding and DNA-accessibility. Interestingly, the extent of DNA protein binding over a range of protein concentration was significantly lower in A-T extracts. In addition the accessibility of the restriction enzyme Eco R1 to protein-bound plasmid was greater when A-T extracts were used. This is in keeping with the reduced binding observed in the filter-binding assay.

Ataxia telangiectasia: a reappraisal of the ocular motor features and their value in the diagnosis of atypical cases

The eye movements of four patients with ataxia telangiectasia (AT), three of whom had an unusual neurological presentation, were studied. All had striking abnormalities of saccadic generation with markedly hypometric saccades, increased saccadic latency, but normal saccadic velocity. Three patients used head thrusts to aid refixation. In addition, there was absence of smooth pursuit and optokinetic nystagmus, and hyperactive vestibular responses. Two of the four patients had, in addition, periodic alternating nystagmus. This combination of an ocular motor apraxia with superadded cerebellar ocular motor abnormalities, and possibly periodic alternating nystagmus, should strongly suggest the diagnosis of AT, even if the clinical syndrome is otherwise atypical.

Ataxia-ocular motor apraxia: a syndrome mimicking ataxia-telangiectasia

We report 14 patients with a slowly progressive syndrome featuring ataxia, choreoathetosis, and ocular motor apraxia in both the horizontal and vertical planes. Although the neurological signs were indistinguishable from those of ataxia-telangiectasia, the onset tended to be later and none of the patients had evidence of multisystemic involvement. Specifically, there was no tendency to frequent infections, and immunoglobulins, alpha-fetoprotein, T- and B-lymphocyte markers, and chromosomes 7 and 14 were normal in all tested patients. The simultaneous absence of telangiectasias and of other nonneurological manifestations made ataxia-telangiectasia an unlikely diagnosis. We suggest that these patients suffer from an unusual type of spinocerebellar degeneration. This syndrome has been observed in different populations from three continents, with a genetic pattern suggesting recessive autosomal inheritance.

Ataxia-telangiectasia or Louis-Bar syndrome

Ataxia-telangiectasia (A-T) is a clinical syndrome that commonly shows oculocutaneous telangiectasia, progressive cerebellar ataxia, recurrent sinopulmonary infections, increased incidence of malignancy, x-ray hypersensitivity, and autosomal recessive inheritance. Profound dysfunction of both humoral and cell-mediated immune systems is demonstrated by low IgA levels, an immature thymus, a poor response to antigenic challenges, and recurrent infections. The high risk of malignancy may be related to poor immune surveillance. Two cases (sisters) are reported demonstrating the typical features of the disease along with the results of a trial of the immunopotentiating drug, levamisole, in one of them. The features of A-T are reviewed and include the more recent findings of elevated serum carcinofetal proteins and chromosomal aberrations.

Immunodeficiency syndromes and the gut

The gastrointestinal tract in immunodeficiency disorders is involved with diseases similar to those seen in the immune competent. However, in some immune deficient states the incidence of gastrointestinal disease is high whereas in others it is no different than in the general population. This review clarifies the unique and specific abnormalities seen in immune deficient states and stresses the newest recognised abnormalities. It highlights the fact that the most frequent and severe abnormalities occur in patients with combined immune deficient states.

Ataxia-without-telangiectasia. Progressive multisystem degeneration with IgE deficiency and chromosomal instability

Three of five siblings developed a progressive neurological disorder during infancy or early childhood characterized by cerebellar ataxia, choreoathetosis and peripheral neuropathy. Immunological studies revealed a marked selective deficiency of serum IgE in all three affected siblings. There was evidence of chromosomal instability in the three affected siblings and in one of the parents. One of the affected siblings also developed acute lymphoblastic leukaemia. In spite of many resemblances, this syndrome differs from classical or complete ataxia telangiectasia in that oculocutaneous telangiectases were lacking, the serum IgA and alpha-fetoprotein levels in this family were normal, there was no gonadal dysgenesis, and the cytogenetic findings were atypical.

Heterogeneity of immunological abnormalities in ataxia-telangiectasia

Peripheral blood mononuclear cells from five patients with ataxia-telangiectasia were evaluated for their reactivity with a panel of monoclonal antibodies directed against T-cell subsets and for their in vitro functions in a pokeweed mitogen-induced immunoglobulin biosynthesis assay. All the patients had significantly reduced proportions of cells identified by monoclonal antibodies to subpopulations of T lymphocytes with helper activity (OKT4 and 5/9) and produced low amounts or no IgA and IgG in vitro. Immunoglobulin biosynthesis was increased by the addition of normal x-irradiated peripheral blood mononuclear cells in one of three patients, suggesting a helper T-cell deficiency in this patient and intrinsic B-cell defects in the other two. Two patients had increased proportions of cells identified by a monoclonal antibody to a subpopulation of T lymphocytes which includes suppressor T cells (OKT8), and their cells were able to suppress immunoglobulin biosynthesis by peripheral blood mononuclear cells from normal donors. These findings indicate heterogeneous disturbances of immunoregulatory mechanisms in ataxia-telangiectasia.

Effects of phenytoin on man's immunity. Evaluation of changes in serum immunoglobulins, complement, and antinuclear antibody

To determine the effects of phenytoin on serum immunoglobulins, complement, and antinuclear antibody conversion, a prospective, five-year longitudinal study was undertaken in 118 patients. Three major diagnostic groups were evaluated: 27 patients with idiopathic epilepsy, 50 with secondary epilepsy, and 41 with neuropathic syndromes without epilepsy. In addition, 83 normal volunteers were studied in a similar manner. Evaluations were performed prior to administration of phenytoin and at six-month intervals thereafter. Prior to treatment, patients with idiopathic epilepsy had a higher than expected incidence (13.5 percent, p less than 0.01) of low serum IgA (less than 61 mg/dl). Patients with secondary epilepsy and neuropathic disorders without epilepsy had a greater than expected incidence (9.2 percent, p less than 0.01; and 12 percent, p less than 0.01, respectively) of high serum IgA (greater than 417 mg/dl). Phenytoin treatment was associated with further decreases in serum IgA in patients with idiopathic epilepsy (p = 0.063) and secondary epilepsy (p = 0.008). Total serum IgE concentrations also decreased significantly in all patient categories during treatment with phenytoin. Minor decreases in serum IgG and IgM were noted, but serum IgD and complement remained unaffected. Antinuclear antibodies were observed with essentially the same frequency (10 percent) before and after phenytoin therapy.

Disorders of B cells and helper T cells in the pathogenesis of the immunoglobulin deficiency of patients with ataxia telangiectasia

The pathogenesis of the immunoglobulin deficiency of 20 patients with ataxia telangiectasia was studied using an in vitro immunoglobulin biosynthesis system. 10 patients had no detectable IgA in their serum as assessed by radial diffusion in agar and 3 had a reduced serum IgA concentration. The peripheral blood mononuclear cells of 17 of the patients and 17 normal controls were cultured with pokeweed mitogen for 12 d and the immunoglobulin in the supernatants measured. The immunoglobulin synthesis was below the lower limit of the normal 95% confidence interval for IgM in 5 patients, for IgG in 8, and for IgA in 14. The mononuclear cells from 9 of the 10 patients with a serum IgA concentration less than 0.1 mg/ml failed to synthesize IgA in vitro. None of the patients manifested excessive suppressor cell activity. All patients had reduced but measurable helper T cell activity for immunoglobulin synthesis by co-cultured normal pokeweed mitogen-stimulated B cells (geometric mean 22% of normal). Furthermore, the addition of normal irradiated T cells to patient peripheral blood mononuclear cells led to an augmentation of IgM synthesis in 15 of 17 and to increased IgG synthesis in 9 of the 17 patients studied, including 9 of the 12 patients who had synthesized IgG before the addition of the irradiated T cells. In addition, IgA synthesis was increased in all eight patients examined that had serum IgA concentrations greater than 0.1 mg/ml. These studies suggest that a helper T cell defect contributes to the diminished immunoglobulin synthesis. However, a helper T cell defect does not appear to be the sole cause since there was no IgA synthesis by the peripheral blood mononuclear cells of 9 of the 10 patients with a profoundly reduced serum IgA even when co-cultured with normal T cells. Furthermore, the cells of the nine patients with profoundly reduced IgA levels examined also failed to produce IgA when stimulated with the relatively helper T cell-independent polyclonal activators, Nocardia water soluble mitogen or Epstein-Barr virus. Taken together these data support the view that the reduced immunoglobulin synthesis of these patients is due to defects of both B cells and helper T cells. Such a broad defect in lymphocyte maturation taken in conjunction with our demonstration of persistent alpha fetoprotein production by ataxia telangiectasia patients provides support for the proposal that these patients exhibit a generalized defect in tissue differentiation.

Natural killer and killer cell activities in patients with primary immunodeficiencies or defects in immune interferon production

Natural cell-mediated cytotoxicity (NCMC) against K-562 target cells was explored in patients with various primary immunodeficiencies. (a) NCMC was present in 2 patients lacking detectable B cells. Conversely, NCMC was depressed in 2 patients with severe combined immunodeficiency presenting a normal number of circulating B cells. These data exclude a major role for B cells in NCMC. (b) NCMC was depressed mainly in patients with severe combined immunodeficiency or with defects affecting cellular immunity, which suggests a major role in NCMC for cells of T lineage. (c) Four patients with various clinical features associated with a lack of immune interferon production exhibited a strikingly depressed NCMC. Interferon thus appears as a major in vivo activator of natural killer (NK) cell activity. (d) Eight patients exhibiting a depressed NK cell activity had a normal killer (K) cell activity against L1210 cells in the presence of rabbit anti-L1210 antiserum. These data are consistent with the assumption that NK and K cell activity are mediated through two distinct cellular mechanisms.

Diagnostic considerations in ataxia-telangiectasia

13 children with ataxia-telangiectasia were followed for 6 years. Unlike previously reported cases, these patients had progressive, debilitating neurological disease and slight pulmonary or infectious symptoms. Immunological dysfunction was variable and endocrinological defects were absent. Oculomotor findings, alpha-fetoprotein levels, and the incidence of chromosomal breakage were the most consistent parameters in the diagnosis of the condition. This disease should be considered in any patient with chronic ataxia, regardless of immunological findings or whether he has a history of infections.

The role of IgE in the immune response to neoplasia: a review

The role of IgE in the immune response to neoplasia has received little attention despite suggestive evidence for an IgE response to tumor specific antigens. A complex interrelationship is known to exist between basophils, eosinophils, histamine, complement, and T cells. The latter cells are known to play a central role in the immune response to neoplasia and, in addition, are now considered important in the production and regulation of IgE, the molecule that may supply an important link between pharmacological and cellular dynamics of a successful anti-tumor response. The evidence for an IgE role in the immune response to tumors, the relationship between atopy and cancer, and the possible mechanisms whereby IgE could enhance tumor rejection are discussed in this review.

Immunological investigations in two brothers with ataxia telangiectasia Louis-Bar

Two of three brothers with the classical signs of ataxia telangiectasia were investigated for their immunological disorders at the ages of 13 and 16 years, respectively. The elder brother also suffers from autoimmune hemolytic anemia, a complication which has not yet been described in the course of ataxia telangiectasia. Immunological investigations made in both brothers showed a reduction in the number and function of T lymphocytes. The number of B lymphocytes was normal, among which there were cells staining for IgA, although serum IgA was absent. It seems possible that this phenomenon is caused by a disturbance in the process of maturation of lymphoid cells with a lack of differentiation into IgA-synthesizing plasma cells.