The primary immunodeficiencies (1)

Sixty-nine kilobases of contiguous human genomic sequence containing the alpha-galactosidase A and Bruton's tyrosine kinase loci

Several disease loci have been mapped to the Xq21.3-Xq22 region of the human X Chromosome (Chr) including X-linked agammaglobulinemia (XLA), Fabry disease, Alport syndrome, and Pelizaeus Merzbacher disease. Upon cloning of the XLA gene, Bruton's tyrosine kinase (btk), both Fabry disease and XLA were mapped within the same 50- to 70-kb interval. In order to investigate the genomic organization of the region surrounding btk and the Fabry disease gene, alpha-galactosidase A (gla), we constructed a 6-cosmid contig spanning the region from 5' of gla to 3' of btk. Two of these cosmids spanning most of the coding sequence and the upstream region of btk and gla, U237D10 and U230D1, were sequenced by a random shotgun strategy combined with automated sequencing, resulting in 69 kb of contiguous genomic sequence. Sequencing of U237D10 showed btk to be comprised of 19 exons spanning over 35 kb. Sequencing of U230D1 showed that the 3' end of gla is 9 kb from the 5' end of btk and also demonstrated the presence of two additional genes in the region immediately 5' to btk. The surprisingly high gene density is similar to that seen previously only in the human major histocompatibility locus.

Predominance of sterile immunoglobulin transcripts in a female phenotypically resembling Bruton's agammaglobulinemia

The transcription pattern of the heavy chain immunoglobulin gene locus was analyzed in a 6-month-old female with agammaglobulinemia characterized by the absence of mature B cells in peripheral blood, arrested B cell development in the bone marrow and lack of germinal center development. DNA sequencing provided no evidence of mutations within the coding region of the Bruton's tyrosine kinase gene. Polymerase chain reaction-generated cDNA libraries from blood and bone marrow were screened initially using JH and CH oligodeoxynucleotide probes and VH family-specific probes. Only 10% of the transcripts constituted mature VDJC mu recombinations. Ninety percent of the cDNA were sterile immunoglobulin transcripts comprised of: DJC mu (DH-JHC mu), JC mu (JH-C mu), EC mu (enhancer spliced to C mu), SC mu and IC mu [corresponding to switch (S) and intron (I) regions spliced to C mu]. In the mature immunoglobulin transcripts, VH use indicated germline expression with little evidence of somatic mutation. All cDNA were of the C mu type. Different D segments, D-D joining events and unknown D-like elements were noted in the DJC mu and VDJC mu transcripts. This pattern of immunoglobulin rearrangements, along with the phenotypic cell surface antigen characteristics (CD19-), suggest that an earlier arrest in B cell development than is characteristic of Bruton's X-linked agammaglobulinemia has occurred in this patient.

The effects of acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on glioma-specific cytotoxic T-cell activity in Fischer 344 rats

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is one of the most potent environmental immunomodulating agents identified so far. Historically, mice have been used to model mammalian immunobiology and most of the data gathered on the immunotoxicity of TCDD has been obtained from studies with mice. However, rats have been used more extensively in toxicological research to establish human risk assessment criteria. A need exists, therefore, to develop a database using the rat model in immunotoxicology so that complete animal toxicity studies can be conducted. We have treated female Fischer 344 rats with a single i.p. dose of 0.3, 3.0, or 30.0 micrograms/kg TCDD or corn oil vehicle and examined cytotoxic T-cell (CTL) activities 24 days following treatment. Syngeneic in vivo tumor-specific CTLs were generated that model cell-mediated immune reactions against neoplastically transformed self antigens. RT2, a virally-induced Fischer 344 rat glioma, and D74, a ethylnitrosurea-induced Fischer 344 rat glioma were used as targets. This immunological parameter was compared to body, thymic, and liver weights as well as liver ethoxyresorufin deethylase (EROD) activity on day 24 post-TCDD treatment. The results indicate that Fischer 344 rats are very sensitive to TCDD as indicated by severe thymic atrophy and EROD induction at all three doses. In contrast, CTL activity was only marginally affected by these same doses of TCDD with only a modest suppression noted at the highest dose. These results indicate that the CTL response in rats may not be useful in characterizing the effects of this xenobiotic on immunocompetence in the rat.

Characterization of germline mutations of the gene encoding Bruton's tyrosine kinase in families with X-linked agammaglobulinemia

Bruton's tyrosine kinase (Btk) has been identified as the protein responsible for the primary immunodeficiency X-linked agammaglobulinemia (XLA) and has been described as a new member of Src-related cytoplasmic protein tyrosine kinases. We have recently characterized the structure of the entire gene encoding Btk and developed a polymerase chain reaction (PCR)-based assay to detect germline mutations within it. In this report we describe six mutations, five of which are novel, of the Btk gene in patients with XLA and demonstrate the inheritance pattern of the defect within the families of the affected individuals. The mutations found include two nonsense and two missense mutations, a single base deletion at an intron acceptor splice site, and a 16-bp insertion. A single strand conformation polymorphism was also found in the 5' end of intron 8 with the same assay. This technique has provided a powerful tool for direct analysis of the Btk gene for the diagnosis of XLA and carrier detection. The identification of new mutations may eventually reveal the role of Btk in the signaling pathways involved in B-cell development.

Membranous glomerulonephritis associated with hepatitis C virus infection in an adolescent

The clinical, laboratory and pathological findings are reported in an adolescent patient with hyper-IgM immunodeficiency syndrome (dysgammaglobulinemia) which was complicated by primary sclerosing cholangitis and membranous glomerulonephritis. Hepatitis C virus (HCV) RNA was detected in serum by the polymerase chain reaction. A possible etiological relationship between hepatitis C virus infection and membranous nephropathy is discussed.

Human severe combined immunodeficiency due to a defect in ZAP-70, a T cell tyrosine kinase

A homozygous mutation in the kinase domain of ZAP-70, a T cell receptor-associated protein tyrosine kinase, produced a distinctive form of human severe combined immunodeficiency. Manifestations of this disorder included profound immunodeficiency, absence of peripheral CD8+ T cells, and abundant peripheral CD4+ T cells that were refractory to T cell receptor-mediated activation. These findings demonstrate that ZAP-70 is essential for human T cell function and suggest that CD4+ and CD8+ T cells depend on different intracellular signaling pathways to support their development or survival.

A new RFLP marker, SP282, at the btk locus for genetic analysis in X-linked agammaglobulinaemia families

X-linked agammaglobulinaemia is an inherited recessive disease in which the primary defect lies in the failure of pre-B cells to develop into mature circulating B cells, due to a defective B-cell cytoplasmic tyrosine kinase (btk). For this study we introduced a new RFLP marker, SP282, which is tightly linked to the XLA locus. In conjunction with the marker DXS178, SP282 was used to identify a carrier female and predict her male offspring to be normal. Subsequently the fetus was shown to have a normal number of circulating B cells, and at 2.5 years of age, the non-affected phenotype of the child was confirmed.

Physical mapping shows close linkage between the alpha-galactosidase A gene (GLA) and the DXS178 locus

X-linked agammaglobulinaemia (XLA) is an inherited disorder characterised by a lack of circulating B-cells and antibodies. While the gene involved in XLA has not yet been identified, the locus for the disorder is tightly linked to the polymorphic marker DXS178, which maps to Xq22. Fabry disease is an X-linked recessive disorder caused by a deficiency in the lysosomal enzyme alpha-galactosidase A. The gene encoding this enzyme has been characterized and also maps to Xq22. Using pulsed field gel electrophoresis we have constructed a long-range restriction map that shows that the alpha-galactosidase A gene (GLA) and DXS178 lie no more than 140 kb apart on a stretch of DNA containing a number of putative CpG islands. We have also isolated yeast artificial chromosome (YAC) clones that confirm this physical linkage. The localisation of DXS178 near the alpha-galactosidase A gene will facilitate carrier detection in Fabry families using restriction fragment length polymorphism (RFLP) analysis. The identification of a number of CpG islands near DXS178 also provides candidate locations for the gene responsible for XLA.

Relationship between plasma cell levels and profile of bronchoalveolar lavage fluid in patients with subacute extrinsic allergic alveolitis

BACKGROUND

Plasma cells are usually absent in bronchoalveolar lavage (BAL) fluid. Extrinsic allergic alveolitis is associated with increased numbers of T and B lymphocytes in BAL fluid, as well as the presence of a few plasma cells. The aim of this study was to investigate whether there is a relationship between the presence of plasma cells and other cells, and immunoglobulin levels in BAL fluid of patients with extrinsic allergic alveolitis.

METHODS

Thirty non-smoking patients with extrinsic allergic alveolitis who had a bronchoalveolar lavage 2-7 days after their last exposure to the causative antigen were selected, retrospectively.

RESULTS

Patients suffering from extrinsic allergic alveolitis with plasma cells in the BAL fluid (n = 18) had increased absolute numbers of lymphocytes, eosinophils and mast cells, a decreased percentage of alveolar macrophages and lower CD4/CD8 ratio, as well as higher immunoglobulin levels, when compared with patients with extrinsic allergic alveolitis having no plasma cells in the BAL fluid (n = 12).

CONCLUSIONS

The results suggest a relationship between the presence of plasma cells and the other constituents in BAL fluid and a more intense alveolitis. In addition there was a positive relationship between the number of plasma cells in BAL fluid and immunoglobulin levels. These data support the concept of local production of immunoglobulins by plasma cells in the lung following antigen exposure in susceptible individuals.

Wiskott Aldrich syndrome: an immunodeficiency syndrome not rare in Western Australia

Wiskott Aldrich syndrome, a combined cellular and humoral X-linked immunodeficiency, is generally considered to be rare. The aim of this study was to ascertain the true prevalence in the paediatric population in Western Australia, describe the clinical features, and summarise the current literature on this unusual condition. All cases of Wiskott Aldrich syndrome presenting to Princess Margaret Hospital in Perth during the period from January 1960 to January 1990 were identified by a retrospective review of case records and by interviewing hospital immunology, haematology and general clinical staff. Nine cases of Wiskott Aldrich syndrome are described, demonstrating that the prevalence of Wiskott Aldrich syndrome in Western Australia is nine times that expected from previous reports. Death occurred in a number of patients before the correct diagnosis was recognised. The clinical features in this group are quite variable. Low isohaemagglutinins, elevated IgE, blunted DTH skin multitest, and very low CD8 numbers are however consistent features. Wiskott Aldrich syndrome may be more prevalent than previously recognised, and should be considered in males with thrombocytopenia and infection.

Hypogammaglobulinemia and rheumatic disease

Primary hypogammaglobulinemia describes a heterogeneous group of immunoglobulin disorders mainly composed of X-linked agammaglobulinemia, common variable immunodeficiency, and selective immunoglobulin (Ig) A deficiency. The most serious problems are related to recurrent infections with high-grade encapsulated bacteria. However, a wide variety of rheumatologic disorders also occur in association with hypogammaglobulinemic states. Septic arthritis with usual bacterial pathogens such as Staphylococcus aureus, and unusual bacteria such as Mycoplasma and Ureaplasma species, have been described in these patients. An aseptic nonerosive polyarticular arthritis that resembles rheumatoid arthritis is seen in 10% to 30% of hypogammaglobulinemic patients. Autoimmune disorders such as immune thrombocytopenic purpura, immune hemolytic anemia, juvenile rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, Sjögren's syndrome, essential mixed cryoglobulinemia, chronic active hepatitis, and sarcoidosis have been reported in hypogammaglobulinemic patients. Finally, to complicate matters, many disease-modifying antirheumatic drugs, including gold, D-penicillamine, sulfasalazine, azathioprine, and cyclophosphamide, cause symptomatic hypogammaglobulinemia in some patients.

The gene involved in X-linked agammaglobulinaemia is a member of the src family of protein-tyrosine kinases

X-linked agammaglobulinaemia (XLA) is a human immunodeficiency caused by failure of pre-B cells in the bone marrow to develop into circulating mature B cells. A novel gene has been isolated which maps to the XLA locus, is expressed in B cells, and shows mutations in families with the disorder. The gene is a member of the src family of proto-oncogenes which encode protein-tyrosine kinases. This is, to our knowledge, the first evidence that mutations in a src-related gene are involved in human genetic disease.

Measles virus-specific cellular immunity in patients with vaccine failure

The cytotoxic T-lymphocyte (CTL) response to measles virus (MV) was studied in blood samples from 13 acute- and early convalescent-phase patients with measles infection despite previous vaccination with the live-MV vaccine. MV CTL responses were also measured in six healthy peer controls who had live-MV vaccination during childhood and in five healthy adults who had a remote history of natural measles. All patients recovered from illness without complication. Acute MV infection was diagnosed on the basis of the Centers for Disease Control criteria and by measuring MV-specific immunoglobulin G (IgG) and IgM antibodies. Elevated IgG titers occurred in 80% of the patients at 1 to 2 weeks and in 100% at 4 weeks postinfection. IgM antibodies were detectable in all patient tested and were elevated in 60% of the patients at 1 to 2 weeks postinfection. The MV-specific CTL response was enhanced in 10 of the 13 patients tested, with a mean maximal lysis of 48.5% +/- 13.3%, compared with that of healthy peer controls who had had live-MV vaccinations during childhood (mean lysis, 14.6% +/- 12.9%; n = 6) and healthy adults with a remote history of natural measles (mean, 30.8% +/- 12.2%; n = 5). Three patients had low MV CTL levels at two time points following measles, with a mean lysis of 12% +/- 1.7%. It is concluded that while there is no evidence for a deficiency in the generation of cellular immunity to MV in the majority of patients with MV vaccine failure, a small number of individuals may fail to develop an enhanced T-cell response following infection.

Cutaneous markers of internal malignancy. I. Malignant involvement of the skin and the genodermatoses

Cutaneous findings often reflect the presence and course of an internal disease. Recognition of external clues is important to facilitate both early diagnosis and prompt treatment of the internal disorder. Early recognition is especially valuable in a patient with an internal malignant disease because intervention may significantly affect survival. In this two-part series, we review the spectrum of cutaneous markers of internal malignancy. Part I focuses on malignant involvement of the skin caused by either direct extension or metastases and the genodermatoses with malignant potential. Part II will be devoted to the paraneoplastic skin manifestations of internal malignancy as well as environmental carcinogens that produce cutaneous features. We also discuss some proposed but controversial associations between skin disease and internal malignancy.

Human immune toxicity

This review examines xenobiotic toxicity to the immune system, stressing in particular those aspects of most relevance to humans. Immunotoxicity is examined especially from three points of view: by what immunological component is affected, by classes of foreign agents that adversely affect the human immune system and by critical evaluation of human case reports and epidemics. Mechanisms by which xenobiotics interrupt cytokine networks are emphasized. The concept that microbial agents, both environmental as well as infectious, may act as immunotoxicants, either alone or in synergism with conventional agents is introduced. Instances of human immunotoxicology are critically evaluated in terms of clinical relevance, i.e. whether increased susceptibility to opportunistic infections or tumor emergence takes place in the affected individuals.

An unusual T-cell surface phenotype in vivo correlates with the failure to proliferate and produce IL-2 in vitro in a patient with common variable immunodeficiency

Stimulation of T-lymphocytes derived from some patients with common variable immunodeficiency (CVID) syndrome results in defective proliferation. The underlying mechanism is related to the inability of stimulated cells to secrete IL-2 while the expression of IL-2 receptor (IL-2R) is normal. We have identified a patient whose peripheral T-cells failed to proliferate and secrete IL-2 upon stimulation. The addition of recombinant IL-2 restored proliferation. The defect did not seem to be caused by accessory cell failure since the patient's adherent cells produced IL-1 and IL-6, and addition of allogeneic irradiated cells did not induce proliferation. Stimulation of CVID T-cells with phorbol esters and Ca2+ ionophore induced both IL-2 secretion and proliferation, indicating the absence of a defect in the transcription and/or translation of the IL-2 gene. The patient's T-cells expressed high levels of CD3. The majority of T-cells expressed the CD38 molecule which is normally found on thymocytes or activated T-cells but not peripheral blood T-cells and HLA-DR, another activation marker. However, CD25 (the IL-2R) and CD1, a marker of more immature thymocytes, were not expressed. Finally, the patient's cells were sensitive to an in vitro corticosteroid treatment. The possibilities that this patient's T-cells represent anergic T-cells or not fully matured thymocytes are discussed.

T cell lines characterize events in the pathogenesis of the Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is a severe immunodeficiency and platelet deficiency disease arising from an X-linked defect. The disease is correctable by transplantation of hematopoietic stem cells, but the product of the defective gene is unidentified and the number of defects in patient blood cells is large. The current hurdle is the need to identify the early pathogenic event(s) that are the cause of other defects. As a step toward this goal, we have generated and examined a panel of interleukin 2-dependent allospecific T cell lines from peripheral lymphocytes of seven WAS patients and five normal individuals. WAS cell lines, like normal lines, undergo vigorous proliferation when challenged with specific allostimulant or with phorbol myristate acetate and ionomycin. Both normal and WAS T cell lines express cell surface molecules CD2, CD3, T cell receptor-alpha/beta, human histocompatibility leukocyte antigen class I, CD45 and CD11a, and varying ratios of CD4 and CD8, and are negative for natural killer cell and monocyte surface molecules. WAS T cell lines express CD43 (sialophorin/leukosialin) with molecular weight and in an amount comparable with normal T cell lines. WAS T cell lines thus do not express defects in CD43 (decreased amount, abnormal molecular weight), previously documented in WAS circulating lymphocytes. On the other hand, as detected by scanning electron microscopy, WAS cell lines exhibit severe morphological abnormalities, including decreased size and density of the microvillus surface projections. The morphological abnormalities of WAS T cell lines are similar to, or more extensive than, those previously reported for WAS peripheral lymphocytes, indicating that the generation of morphological (cytoarchitectural) defects is an early pathogenic event in this disease. The findings suggest that the gene that is defective in the WAS encodes a protein that normally functions to maintain or regulate the cytoskeletal structure of blood cells.

Infections in the compromised host

The normal defense mechanisms against infection include (1) normal skin and mucous membranes, (2) humoral immunity, (3) phagocytic system, and (4) cellular immunity. The compromised (immunocompromised) host is an individual who has one or more deficiencies in these defense mechanisms. This article reviews potential infections in the compromised host as well as an approach to evaluation of these patients.

Carrier detection and prenatal diagnosis of X-linked agammaglobulinemia

We investigated the pregnant mother of a boy with X-linked agammaglobulinemia (XLA) but with no family history of immune disease. The X-inactivation pattern was found, using a methylation-sensitive probe, to be skewed in the maternal B cells but random in the polymorphonuclear cells, indicating carrier status and a 50% risk of inheritance for her male fetus. Using probes assigned to regions on either side of the XLA locus and defining RFL polymorphism, we excluded for the first time a diagnosis of XLA on a chorionic villus sample, with a risk of error less than 0.003. Immunological studies performed at the 19th week of gestation and 3 days after birth confirmed normality. Carrier detection based on the X-chromosome inactivation pattern, together with prenatal studies using probes close to the disease locus, thus permits prenatal diagnosis in families with isolated cases of XLA.

Neuropathology of Immunosuppression

Traditionally, the brain has been considered an "immunologically privileged" organ. Under normal conditions, the blood-brain barrier (BBB) is highly effective in preventing both cellular and humoral constituents of the blood from entering the brain parenchyma. In certain pathological conditions, such as viral infections and demyelinating disorders, the BBB may become altered, activated T cells and monocytes may gain access to the brain parenchyma, and microglia may assume the functions of antigen-presenting cells and macrophages. Naturally-occurring or clinically-induced immunosuppression may dramatically alter various cellular and/or humoral aspects of the immune system. Consequently, the brain may become susceptible to disorders that would otherwise be excluded or may develop more severe manifestations of diseases, such as certain infections. This review considers the neuropathologic aspects of various conditions that may be encountered in the setting of both acquired and inherited immunosuppression. The major categories include infectious, neoplastic, vascular, and metabolic disorders. The review also briefly addresses the neuropathology of complications of chemotherapeutic agents, radiotherapy, and organ transplantation inasmuch as they often occur in the clinical setting of acquired immunosuppression.

Evidence for failure of V(D)J recombination in bone marrow pre-B cells from X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) results from a failure of B lymphoid development. We have previously examined pre-B cell hybrids from three patients with XLA and found them to be limited to production of a novel germ line transcript of the Ig H chain locus composed of a leader sequence (LS) spliced to the constant region of mu chain (C mu) as mRNA and polypeptide. These transcripts result from transcriptional activation of the germ line heavy chain locus from an LS exon upstream of the embryonic JH locus. Germ line LS-C mu transcripts are produced by pre-B cells from normal bone marrow and fetal liver, indicating that they are products of normal pre-B cell development, as part of the process of transcriptional activation to provide access for the recombinase. Bone marrow from three patients with XLA has been examined directly by polymerase chain reaction amplification to determine whether the exclusive production of LS-C mu by XLA pre-B cell hybrids is representative of XLA pre-B cells. I report that LS-C mu is the predominant Ig molecule produced by XLA pre-B cells, with limited production of the D mu product of DJH intermediate stage of V(D)J recombination. Mature VHDJH recombinations were not detected with a variety of primers that amplify VH sequences. I conclude that XLA is associated with a limitation in V(D)J recombination that may cause the failure of pre-B cell development.

Germ line transcription of the immunoglobulin heavy chain locus directs production of mu chain without VDJ

Immunoglobulin VDJ recombination is associated with transcriptional activation of the Ig variable region elements. We have previously described a novel Ig mu chain protein and mRNA produced by pre-B cell hybrids from normal and X-linked agammaglobulinemic bone marrow. We have now characterized the mRNA encoding this protein and find that it is composed of a 5' leader sequence spliced to C mu (LS-C mu), lacking the variable (V), diversity (D), and joining (J) gene sequences. The leader sequence is encoded by a novel exon 16 kb upstream of the JH locus. Transcription of the germ line heavy chain locus from this LS exon results in transcriptional activation of the JH locus, apparently the initial step in commitment to B lymphoid development. Polymerase chain reaction amplification of normal bone marrow shows that these germ line LS-C mu transcripts are a product of bone marrow pre-B cells. Production of LS-C mu commences a sequential process of transcriptional activation, with concordant translation of Ig rearrangement intermediates, in the process of creating a productive VDJ rearrangement.

Cutaneous lesions as a clue to severe combined immunodeficiency

A 2-month-old boy experienced cutaneous lesions that revealed an underlying severe, combined immunodeficiency (SCID). It is important to recognize cutaneous manifestations of primary immunodeficiency disorders, as they may provide the earliest clue to a defect in immune function.

Hyper-IgM immunodeficiency syndrome: influence of lymphokines on in vitro maturation of peripheral B cells

Peripheral B cells from six patients affected with the hyper-IgM immunodeficiency syndrome, characterized by an absence of IgG and IgA in serum with a concomitant elevated level of IgM, were analyzed for phenotypic and functional characteristics. We report that although the membrane antigenic pattern expression was characteristic of mature B cells, B cells from most patients exhibited an impairment in their in vitro response to several lymphokines, such as recombinant interleukin 2 (rIL-2) and low molecular weight B-cell growth factor (BCGF), that induce proliferation of anti-mu-activated B cells. This impairment was also found in response to a lymphokine mixture from a CD2-activated T-cell clone. The decrease in lymphokine-induced B-cell proliferation was accompanied by a low B-cell differentiation, whether patients' B cells were stimulated by the T-cell clone supernatant or rIL-2 and rIL6, lymphokines able to support differentiation of Staphylococcus aureus Cowan I (SAC)-activated B cells. In addition, none of the lymphokines tested were able to induce patients' B cells to switch from IgM-secreting cells to IgG- and IgA-secreting cells. We conclude that this syndrome is associated with a defect in lymphokine-dependent maturation of B lymphocytes, although the T- or the B-cell origin of the defect still cannot be determined.

Cellular infiltration of the vitreous in a patient with X-linked immunodeficiency with increased IgM

We studied visual impairment caused by benign lymphoid infiltration of the vitreous bilaterally, as a complication of a primary immunodeficiency, X-linked immunodeficiency with increased IgM in an 8-year-old boy. Immunophenotyping of a vitreous aspirate showed a mixed cell population, including lymphocytes (T helper, suppressor-cytotoxic T cells, and B cells) and macrophages. Cultures of the vitreous were negative for bacterial or fungal pathogens. The vitreous infiltrates have been resistant to treatment with corticosteroids and cytotoxic agents.

Long-term follow-up of chronic therapy resistant purulent rhinitis in children

Forty children diagnosed as having chronic purulent rhinitis unresponsive to medical and surgical management were studied. After a mean follow-up of six years and nine months the condition resolved spontaneously in 95% of the children, usually after reaching the age of 7 years.

Gastric abnormalities in humoral immune deficiency syndromes

Patients with late-onset hypogammaglobulinaemia have a very high risk of developing gastric cancer. In such patients there is a high frequency of atrophy of the gastric mucosa. This is reflected in low gastrin content of the antral mucosa, low serum pepsinogen A level and pepsinogen A/C ratio, and reduced serum gastrin secretion in response to bombesin stimulation. There is no evidence to support a role of Helicobacter pylori infection in the aetiopathology of these gastric abnormalities, although prior infection cannot be excluded with certainty. Since patients with early-onset hypogammaglobulinaemia and X-linked agammaglobulinaemia do not show this increased frequency of gastric abnormalities, it is unlikely that the immunoglobulin deficiency per se is responsible for the development of the gastric abnormalities found in patients with late-onset hypogammaglobulinaemia. Because of the very high risk of gastric cancer, regular endoscopic screening is warranted in patients with late-onset hypogammaglobulinaemia.

X-linked immunodeficiencies: clues to genes involved in T- and B-cell differentiation

There are five major human X-linked immunodeficiencies, each with a characteristic impairment of T-and/or B-cell differentiation. The molecular bases of these diseases remain unknown but, as Geneviève de Saint Basile and Alain Fischer report, major steps towards that goal have been taken: the location of the defective genes has been precisely defined and the cell lineages and stages of differentiation in which the genes are expressed have been partly identified.

CD3+ T cells in severe combined immunodeficiency (SCID) mice. V. Allogeneic T cells engrafted into SCID mice do not induce graft-versus-host disease in spite of the absence of host veto and natural suppressor cell activity

Intravenous injection of 10(6) to 10(7) non-fractionated spleen cells (SC) from C57BL/6 (B6, H-2b) mice into completely allogeneic, immunodeficient H-2d severe combined immuno deficiency (scid) mice leads to engraftment of allogeneic donor T cells. Mice analysed in the tenth week posttransfer had engrafted donor-type CD4+ and CD8+ T cells in the spleens but showed no clinical evidence of graft-versus-host disease (GVHD). Transfer of allogeneic T cells engrafted in scid recipients did not induce GVHD upon i.v. injection into secondary scid recipients and lead in most recipients to engraftment of a pure CD4+ T-cell population. Experiments were carried out to investigate the reason(s) for the lack of GVHD in recipient scid mice, i.e. the presence of allotolerance in the engrafted donor T cells. Scid spleen cells (SC) efficiently stimulated alloreactive responses of B6 T cells: scid SC stimulated H-2d-specific cytotoxic responses in a B6 anti-scid mixed lymphocyte culture in vitro, and scid SC injected i.v. into B6 mice efficiently primed splenic cytotoxic lymphocyte precursors against H-2d alloantigens. Moreover when assayed in vitro, no veto activity or natural suppressor activity was detectable in scid SC. These data demonstrate that tolerizing mechanisms currently believed to operate in vivo can not explain the fact that allogeneic T cells injected i.v. into immunodeficient scid mice become tolerized against host-type alloantigens. Our results are discussed in the light of clinical experience of allogeneic T-cell transfer in scid infants.

X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) patients manifest a very low production of immunoglobulins (Ig) of all classes and plasma cells are virtually absent. The XLA gene plays a crucial role in the transition of pre-B cells to later B cell stages, as hardly any slg-positive B lymphocytes can be detected. In the bone marrow almost normal numbers of pre-B lymphocytes are present. These cytoplasmatic C mu+ pre-B lymphocytes appear to express truncated M heavy chain molecules lacking the variable region segment. The T lymphocyte compartment is intact: the numbers of mature T cell receptor (TcR) alpha beta expressing T lymphocyte populations and their proliferative responses to antigens are normal. That the B cells are primary and exclusively affected was proven by X-chromosome inactivation studies. There is no evidence that the XLA gene is directly involved in the Ig gene rearrangements since B lymphoblastoid cell lines (BLCLs) established from peripheral blood of XLA patients were found to produce IgM molecules composed of complete Ig heavy and light chains and were shown to contain normal VHDJH recombinations. The data do not exclude the involvement of the XLA gene in a B cell specific process that makes the Ig loci accessible for recombination. Investigations on the degree of diversity of immunoglobulins generated by XLA patients exposed no limitations in the VH family usage. Sequence analysis of expressed VH3 and VH4 rearrangements however revealed that some genetic elements of the Ig locus might be over-represented and that a high portion of rearrangements was generated by unconventional mechanisms. By restriction length polymorphism (RFLP) and pulsed field gel electrophoreses analyses the XLA gene was mapped to an 8- to 12-Mb DNA fragment located in the Xq22 region. The known location of the XLA gene on the X-chromosome with closely linked RFLP markers and the availability of X-chromosome inactivation assays provides methods for carrier detection and prenatal diagnosis.

Phenotypical and functional characterization of double-negative (CD4-CD8-) alpha beta T-cell receptor positive cells from an immunodeficient patient

We have characterized CD4-CD8- double-negative (DN) alpha beta TCR+ T cells from a patient with immunodeficiency, lymphocytosis, lymphadenopathy, and hepatosplenomegaly. The majority of peripheral blood lymphocytes were DN alpha beta TCR+ T cells as evaluated by FACS and biochemical analysis. The DN T cells showed the following phenotype: alpha beta TCR+, gamma delta TCR-, CD2+, CD3+, CD4-, CD5+, CD7-, CD8-, CD16-, CD25-, CD26-, CD28+, CD45RO-, CD45RA+, CD57+, and HLA-DR+. Both southern blot analysis of TCR genes and FACS analysis applying a panel of V beta and V alpha monoclonal antibodies (MoAbs) indicated a polyclonal T-cell expansion. Thymic biopsy showed normal histology, whereas lymph node biopsy samples showed altered histological and immunohistological patterns with markedly expanded paracortical areas containing the DN T cells of the same phenotype as found in peripheral blood T cells. In functional studies, the DN T cells showed a profoundly reduced proliferative response upon stimulation with mitogens as well as MoAbs against the TCR/CD3 complex, CD2, and CD28, respectively. Addition of exogenous interleukin-2 (IL-2) only minimally augmented the proliferative response. In contrast, the addition of a combination of Ca2+ ionophore and phorbol 12-myristate 13-acetate (PMA) restored the proliferative response of the DN T cells to almost normal levels. This observation strongly suggests that the protein kinase C activity of the DN T cells was intact, but that the normal mechanism for transmembrane signal transduction was impaired in these unusual DN T cells.

Genetics of human X-linked immunodeficiency diseases

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