[Extracorporeal membrane oxygenation in critically ill neonates and children]

Extracorporeal membrane oxygenation is used as a last resort during neonatal and pediatric resuscitation in case of refractory circulatory or respiratory failure under maximum conventional therapies. Different types of ECMO can be used depending on the initial failure. The main indications for ECMO are refractory respiratory failure (acute respiratory distress syndrome, status asthmaticus, severe pneumonia, meconium aspiration syndrome, pulmonary hypertension) and refractory circulatory failure (cardiogenic shock, septic shock, refractory cardiac arrest). The main contraindications are a gestational age under 34 weeks or birth weight under 2kg, severe underlying pulmonary disease, severe immune deficiency, a neurodegenerative disease and hereditary disease of hemostasis. Neurological impairment can occur during ECMO (cranial hemorrhage, seizure or stroke). Nosocomial infections and acute kidney injury are also frequent complications of ECMO. The overall survival rate of ECMO is about 60 %. This survival rate can change depending on the initial disease: from 80 % for meconium aspiration syndrome to less than 10 % for out-of-hospital refractory cardiac arrest. Recently, mobile ECMO units have been created. These units are able to perform ECMO out of a referral center for untransportable critically ill patients.

Hyper-immunoglobulin M syndrome type 3 with normal CD40 cell surface expression

Mutations of the CD40 gene have been found in patients with autosomal recessive hyper-immunoglobulin M (HIGM) syndrome type 3. Five patients from four unrelated families with CD40 mutation have been reported so far. Clinical manifestations include recurrent sinopulmonary infections, Pneumocystis carinii pneumonia and Cryptosporidium parvum infection. Affected patients typically have very low levels of IgG and IgA and normal or high levels of IgM. Flow cytometry analysis of these five patients demonstrated that peripheral blood B lymphocytes lacked expression of surface CD40. Herein, we present two siblings from second-degree consanguineous Turkish parents with homozygous CD40 deletion of four nucleotides including the stop codon resulting presumably to a longer protein. Clinical and immunological profile of these patients is similar to the already reported HIGM3 patients except normal CD40 expression on B lymphocytes. This observation emphasizes the requirement of CD40 mutation analysis for definite diagnosis of HIGM3 despite normal flow cytometric expression of CD40, particularly if the immunological and clinical profile is suggestive for HIGM3.

Intravenous immunoglobulins--understanding properties and mechanisms

High-dose intravenous immunoglobulin (IVIg) preparations are used currently for the treatment of autoimmune or inflammatory diseases. Despite numerous studies demonstrating efficacy, the precise mode of action of IVIg remains unclear. Paradoxically, IgG can exert both pro- and anti-inflammatory activities, depending on its concentration. The proinflammatory activity of low-dose IVIg requires complement activation or binding of the Fc fragment of IgG to IgG-specific receptors (FcgammaR) on innate immune effector cells. In contrast, when administered in high concentrations, IVIg has anti-inflammatory properties. How this anti-inflammatory effect is mediated has not yet been elucidated fully, and several mutually non-exclusive mechanisms have been proposed. This paper represents the proceedings of a session entitled 'IVIg--Understanding properties and mechanisms' at the 6th International Immunoglobulin Symposium that was held in Interlaken on 26-28 March 2009. The presentations addressed how IgG may affect the cellular compartment, evidence for IVIg-mediated scavenging of complement fragments, the role of the dimeric fraction of IVIg, the anti-inflammatory properties of the minor fraction of sialylated IgG molecules, and the genetic organization and variation in FcgammaRs. These findings demonstrate the considerable progress that has been made in understanding the mechanisms of action of IVIgs, and may influence future perspectives in the field of Ig therapy.

6th International Immunoglobulin Symposium: poster presentations

The posters presented at the 6th International Immunoglobulin Symposium covered a wide range of fields and included both basic science and clinical research. From the abstracts accepted for poster presentation, 12 abstracts were selected for oral presentations in three parallel sessions on immunodeficiencies, autoimmunity and basic research. The immunodeficiency presentations dealt with novel, rare class-switch recombination (CSR) deficiencies, attenuation of adverse events following IVIg treatment, association of immunoglobulin (Ig)G trough levels and protection against acute infection in patients with X-linked agammaglobulinaemia (XLA) and common variable immunodeficiency (CVID), and the reduction of class-switched memory B cells in patients with specific antibody deficiency (SAD). The impact of intravenous immunoglobulin on fetal alloimmune thrombocytopenia, pregnancy and postpartum-related relapses in multiple sclerosis and refractory myositis, as well as experiences with subcutaneous immunoglobulin in patients with multi-focal motor neuropathy, were the topics presented in the autoimmunity session. The interaction of dendritic cell (DC)-SIGN and alpha2,6-sialylated IgG Fc and its impact on human DCs, the enrichment of sialylated IgG in plasma-derived IgG, as wells as prion surveillance and monitoring of anti-measles titres in immunoglobulin products, were covered in the basic science session. In summary, the presentations illustrated the breadth of immunoglobulin therapy usage and highlighted the progress that is being made in diverse areas of basic and clinical research, extending our understanding of the mechanisms of immunoglobulin action and contributing to improved patient care.

Isolated growth hormone deficiency in a patient with immunoglobulin class switch recombination deficiency

Growth hormone deficiency (GHD) may be associated with a number of immunodeficiency diseases, but its association with immunoglobulin class switch recombination (Ig CSR) deficiencies is very rare. We report the case of a patient with a history of recurrent diarrhea and respiratory infections diagnosed with hyper IgM syndrome on the basis of immunological findings (low serum levels of IgG and IgA and an elevated serum level of IgM). In view of the patient's short stature, growth hormone evaluation was performed and growth hormone deficiency confirmed. The patient received growth hormone therapy in addition to Ig replacement therapy and antibiotics and responded well. As the coding regions of the genes known to be responsible for Ig CSR (CD40L, CD40, AICDA, and UNG) were intact in our patient, this might be a new form of Ig CSR deficiency.

Hyper-IgM syndromes: a model for studying the regulation of class switch recombination and somatic hypermutation generation

Several genetic defects in class switch recombination, which lead to a hyper-IgM syndrome, have been described recently in humans. In addition to the well known role of CD40-ligand-CD40 interaction, these pathologies demonstrate definitively the requirement of CD40-mediated nuclear factor kappa B activation and the essential role of a recently described molecule, the activation-induced cytidine deaminase in an efficient humoral response, which includes class switch recombination and the production of high-affinity antibodies.

Terminal defects of B lymphocyte differentiation

In humans several abnormalities can occur during terminal B cell differentiation, leading to primary humoral immunodeficiencies. A recent study provided evidence of a qualitative defect of the affinity antibody maturation in some patients affected with common variable immunodeficiency syndrome, the molecular basis of which remains unknown. Several genetic defects in class switch recombination leading to a hyper-IgM syndrome have recently been delineated. Besides the well-known role of CD40-CD40 ligand interaction, they definitively demonstrate the requirement of CD40-mediated nuclear factor kappa B activation and the essential role of a newly described molecule, the activation-induced cytidine deaminase, in B cell terminal differentiation.

Mutations of CD40 gene cause an autosomal recessive form of immunodeficiency with hyper IgM

CD40 is a member of the tumor necrosis factor receptor superfamily, expressed on a wide range of cell types including B cells, macrophages, and dendritic cells. CD40 is the receptor for CD40 ligand (CD40L), a molecule predominantly expressed by activated CD4(+) T cells. CD40/CD40L interaction induces the formation of memory B lymphocytes and promotes Ig isotype switching, as demonstrated in mice knocked-out for either CD40L or CD40 gene, and in patients with X-linked hyper IgM syndrome, a disease caused by CD40L/TNFSF5 gene mutations. In the present study, we have identified three patients with an autosomal recessive form of hyper IgM who fail to express CD40 on the cell surface. Sequence analysis of CD40 genomic DNA showed that one patient carried a homozygous silent mutation at the fifth base pair position of exon 5, involving an exonic splicing enhancer and leading to exon skipping and premature termination; the other two patients showed a homozygous point mutation in exon 3, resulting in a cysteine to arginine substitution. These findings show that mutations of the CD40 gene cause an autosomal recessive form of hyper IgM, which is immunologically and clinically undistinguishable from the X-linked form.

Human genetic defects in class-switch recombination (hyper-IgM syndromes)

Several genetic defects in class-switch recombination, leading to hyper-IgM syndromes, have been recently described in humans. Besides the well-known role of interaction between CD40-ligand and CD40, these pathological conditions definitively demonstrate the requirement of CD40-mediated NF-kappaB activation and the essential role of a newly described molecule, activation-induced cytidine deaminase (AID), in B cell terminal differentiation.

[Development of specific immunity in prenatal life]

The various defense mechanisms of specific immunity, which involves the T and B lymphocytes and the antigen presenting cells, are gradually developed during intra-uterine life. The first hematopoietic organ is the yolk sac which appears at the 4th week of development. Thereafter, the hematopoiesis takes place in the fetal liver (from the 6th week) followed by the bone-marrow during the 3rd trimester. The differentiation of the T lymphocytes begins around the 10th week. The thymic epithelial rudiments appear during the 7th week and the thymus migrates to its definitive place at ten weeks. It is then colonized by the T cell precursors, which there undergo their maturation process. From the 12th week of development, mature T cells are readily detectable in lymphoid organs and fetal blood. The maturation of B cells, which occurs firstly in fetal lever, and thereafter in bone marrow begins also early in fetal life (12th week). The antigen presenting cells, the precursors of which are detected in the yolk sac as soon as 4-6 weeks, are normally present and functional in secondary lymphoid organs as soon as 12 weeks. Thus, the specific immune response appears possible by the end of the 1st trimester. However, the naive nature of T and B lymphocytes is responsible for a delayed, slow and relatively ineffective primary response. This observation explains the particular susceptibility of neonates, especially premature neonates to bacterial and viral infections. The various antigenic stimulations and T/B cell cooperations allow a complete maturation of the immune system during the first years of life.

Anti-B cell and anti-cytokine therapy for the treatment of post-transplant lymphoproliferative disorder: past, present, and future

Epstein-Barr virus (EBV)-induced post-transplant lymphoproliferative disorder (PTLD) is a rare but severe complication of solid organ and bone-marrow transplantation. When possible, reduction of immunosuppressive treatment or surgery for localized disease may cure PTLD. Therapeutic approaches using chemotherapy or antiviral drugs have limited effects on survival. Adoptive immunotherapy with donor T cell infusions has shown promising results in bone-marrow transplantation. The use of anti-B cell monoclonal antibodies is herein reported as a safe and efficient therapy for severe PTLD. Because IL6 has been described as a growth factor for EBV-infected B cells, anti-IL6 monoclonal antibody therapy was also tested in a phase I-II clinical trial, the results of which are summarized.

Treatment of B-lymphoproliferative disorder with a monoclonal anti-interleukin-6 antibody in 12 patients: a multicenter phase 1-2 clinical trial

Severe T-cell immunodeficiency after solid organ or bone marrow transplantation may result in the uncontrolled outgrowth of latently Epstein-Barr virus-infected B cells, leading to B-lymphoproliferative disorder (BLPD). Given the potentially important pathogenic role of IL-6 in BLPD, it was tested whether the in vivo neutralization of IL-6 by a monoclonal anti-IL-6 antibody could contribute to the control of BLPD. Safety and efficacy were assessed in 12 recipients of transplanted organs who had BLPD refractory to the reduction of immunosuppression over 8 days. Five patients received 0.4 mg/kg per day. The next 7 patients received 0.8 mg/kg per day. Treatment was scheduled to last 15 days. It was completed in 10 patients, and in the other 2 patients was discontinued early (days 10 and 13, respectively) because of disease progression. Treatment tolerance was good, and no major side effects were observed. High C-reactive protein levels were found in 9 patients before treatment but were normalized under treatment in all patients, demonstrating efficient IL-6 neutralization. Complete remission (CR) was observed in 5 patients and partial remission (PR) in 3 patients. Relapse was observed in 1 of these 8 patients in whom remission was observed. This relapse was unresponsive to treatment. Disease was stable in 1 patient, but it progressed in 3 patients. Seven patients are alive and well. Two patients died because of disease progression, and 3 patients died while in CR (chronic rejection in 2 patients and BLPD sequelae in 1 patient). These data suggest that the anti-IL-6 antibody is safe and should be further explored in the treatment of BLPD.

X-linked anhidrotic ectodermal dysplasia with immunodeficiency is caused by impaired NF-kappaB signaling

The molecular basis of X-linked recessive anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) has remained elusive. Here we report hypomorphic mutations in the gene IKBKG in 12 males with EDA-ID from 8 kindreds, and 2 patients with a related and hitherto unrecognized syndrome of EDA-ID with osteopetrosis and lymphoedema (OL-EDA-ID). Mutations in the coding region of IKBKG are associated with EDA-ID, and stop codon mutations, with OL-EDA-ID. IKBKG encodes NEMO, the regulatory subunit of the IKK (IkappaB kinase) complex, which is essential for NF-kappaB signaling. Germline loss-of-function mutations in IKBKG are lethal in male fetuses. We show that IKBKG mutations causing OL-EDA-ID and EDA-ID impair but do not abolish NF-kappaB signaling. We also show that the ectodysplasin receptor, DL, triggers NF-kappaB through the NEMO protein, indicating that EDA results from impaired NF-kappaB signaling. Finally, we show that abnormal immunity in OL-EDA-ID patients results from impaired cell responses to lipopolysaccharide, interleukin (IL)-1beta, IL-18, TNFalpha and CD154. We thus report for the first time that impaired but not abolished NF-kappaB signaling in humans results in two related syndromes that associate specific developmental and immunological defects.

Mutations in activation-induced cytidine deaminase in patients with hyper IgM syndrome

Recent studies have shown that mutations in a newly described RNA editing enzyme, activation-induced cytidine deaminase (AID), can cause an autosomal recessive form of hyper IgM syndrome. To determine the relative frequency of mutations in AID, we evaluated a group of 27 patients with hyper IgM syndrome who did not have defects in CD40 ligand and 23 patients with common variable immunodeficiency. Three different mutations in AID were identified in 18 patients with hyper IgM syndrome, including 14 French Canadians, 2 Lumbee Indians, and a brother and sister from Okinawa. No mutations were found in the remaining 32 patients. In the group of patients with hyper IgM syndrome, the patients with mutations in AID were older at the age of diagnosis, were more likely to have positive isohemagglutinins, and were less likely to have anemia, neutropenia, or thrombocytopenia. Lymphoid hyperplasia was seen in patients with hyper IgM syndrome and normal AID as well as the patients with hyper IgM syndrome and defects in AID.

Activation-induced cytidine deaminase (AID) deficiency causes the autosomal recessive form of the Hyper-IgM syndrome (HIGM2)

The activation-induced cytidine deaminase (AID) gene, specifically expressed in germinal center B cells in mice, is a member of the cytidine deaminase family. We herein report mutations in the human counterpart of AID in patients with the autosomal recessive form of hyper-IgM syndrome (HIGM2). Three major abnormalities characterize AID deficiency: (1) the absence of immunoglobulin class switch recombination, (2) the lack of immunoglobulin somatic hypermutations, and (3) lymph node hyperplasia caused by the presence of giant germinal centers. The phenotype observed in HIGM2 patients (and in AID-/- mice) demonstrates the absolute requirement for AID in several crucial steps of B cell terminal differentiation necessary for efficient antibody responses.

Gastric adenocarcinoma in a patient with X-linked agammaglobulinaemia

Patients with primary immunodeficiencies are at high risk for developing haematological malignancies and, to a lesser degree, carcinoma. We report a patient with ascertained X-linked agammaglobulinaemia who developed a gastric carcinoma involving the distal part of the stomach associated with chronic atrophic gastritis and intestinal metaplasia. These latter conditions are considered to be precursor conditions and the role of chronic infections is likely. Patients with X-linked agammaglobulinaemia, as with other primary immunodeficiencies, could benefit from regular gastrointestinal evaluation, leading to early diagnosis and treatment of carcinoma.

A syndrome involving intrauterine growth retardation, microcephaly, cerebellar hypoplasia, B lymphocyte deficiency, and progressive pancytopenia

We report a new complex syndrome involving profound failure to thrive with severe intrauterine growth retardation, cerebellar abnormalities, microcephaly, a complete lack of B lymphocyte development, and secondary, progressive marrow aplasia. B cell differentiation was found to be blocked at the pro-B cell stage. Although not strictly proven, a genetic origin is likely, according to similar cases reported in the literature. Three candidate genes, PAX5, encoding B cell-specific activator protein, a factor involved in B cell lineage commitment, stromal cell-derived factor 1, and CXCR4, encoding a chemokine and its receptor, respectively, were thought to be responsible for this disease, given the similarity between the phenotype of the corresponding knock-out mice and the clinical features of the patient. However, the genomic DNA sequences of these 3 genes were normal, and normal amounts of stromal cell-derived factor 1 and CXCR4 were present. These data strongly suggest that another molecule is involved in early B cell differentiation, hematopoiesis, and cerebellar development in humans.

Activation of the Janus kinase 3-STAT5a pathway after CD40 triggering of human monocytes but not of resting B cells

CD40/CD40 ligand interactions play a key role in the immune responses of B lymphocytes, monocytes, and dendritic cells. The signal transduction events triggered by cross-linking of the CD40 receptor have been widely studied in B cell lines, but little is known about signaling following CD40 stimulation of monocytes and resting tonsillar B cells. Therefore, we studied the CD40 pathway in highly purified human monocytes and resting B cells. After CD40 triggering, a similar activation of the NF-kappaB (but not of the AP-1) transcription factor complex occurred in both cell preparations. However, the components of the NF-kappaB complexes were different in monocytes and B cells, because p50 is part of the NF-kappaB complex induced by CD40 triggering in both monocytes and B cells, whereas p65 was only induced in B cells. In contrast, although the Janus kinase 3 tyrosine kinase was associated with CD40 molecules in both monocytes and resting B cells, Janus kinase 3 phosphorylation induction was observed only in CD40-activated monocytes, with subsequent induction of STAT5a DNA binding activity in the nucleus. These results suggest that the activation signals in human B cells and monocytes differ following CD40 stimulation. This observation is consistent with the detection of normal CD40-induced monocyte activation in patients with CD40 ligand+ hyper IgM syndrome in whom a defect in CD40-induced B cell activation has been reported.

TGF-beta 1 prevents the noncognate maturation of human dendritic Langerhans cells

TGF-beta 1 is critical for differentiation of epithelial-associated dendritic Langerhans cells (LC). In accordance with the characteristics of in vivo LC, we show that LC obtained from human monocytes in vitro in the presence of TGF-beta 1 1) express almost exclusively intracellular class II Ags, low CD80, and no CD83 and CD86 Ags and 2) down-regulate TNF-RI (p55) and do not produce IL-10 after stimulation, in contrast to dermal dendritic cells and monocyte-derived dendritic cells. Surprisingly, while LC exhibit E-cadherin down-regulation upon exposure to TNF-alpha and IL-1, TGF-beta 1 prevents the final LC maturation in response to TNF-alpha, IL-1, and LPS with respect to Class II CD80, CD86, and CD83 Ag expression, loss of FITC-dextran uptake, production of IL-12, and Ag presentation. In sharp contrast, CD40 ligand cognate signal induces full maturation of LC and is not inhibited by TGF-beta 1. The presence of emigrated immature LCs in human reactive skin-draining lymph nodes provides in vivo evidence that LC migration and final maturation may be differentially regulated. Therefore, due to the effects of TGF-beta 1, inflammatory stimuli may not be sufficient to induce full maturation of LC, thus avoiding potentially harmful immune responses. We conclude that TGF-beta 1 appears to be responsible for both the acquisition of LC phenotype, cytokine production pattern, and prevention of noncognate maturation.

CD40 ligand expression deficiency in a female carrier of the X-linked hyper-IgM syndrome as a result of X chromosome lyonization

We report on the case of a girl with an immune deficiency characterized by recurrent infections of the upper and lower respiratory tract, low IgG and IgA serum levels as well as deficiency of the in vivo antibody response. Since this patient is the sister of a boy affected with a hyper-IgM syndrome due to a defect in CD40 ligand (CD40L) expression, the involvement of CD40L in this phenotypic expression was investigated. A very low fraction of activated T cells (5%) in this female patient expressed CD40L. This resulted from the presence of a heterozygous CD40L nonsense mutation associated with a skewed pattern of X chromosome inactivation as determined by methylation pattern analysis. Although carriers of X-linked hyper-IgM are considered to be asymptomatic, this study indicates that extreme lyonization of the normal X can lead to a mild expression of the hyper-IgM syndrome which is similar to common variable immune deficiency (CVID). Therefore, it is possible that some cases of CVID in females represent partial deficiency of CD40L expression in carriers of the CD40L mutation.

Inherited interleukin 12 deficiency in a child with bacille Calmette-Guérin and Salmonella enteritidis disseminated infection

Interferon-gamma receptor ligand-binding chain (IFN-gammaR1) or signaling chain (IFN-gammaR2) deficiency, like interleukin 12 receptor beta1 chain (IL-12Rbeta1) deficiency, predispose to severe infections due to poorly virulent mycobacteria and salmonella. A child with bacille Calmette-Guérin and Salmonella enteritidis infection was investigated. Mutations in the genes for IFN-gammaR1, IFN-gammaR2, IL-12Rbeta1, and other molecules implicated in IL-12- or IFN-gamma-mediated immunity were sought. A large homozygous deletion within the IL-12 p40 subunit gene was found, precluding expression of functional IL-12 p70 cytokine by activated dendritic cells and phagocytes. As a result, IFN-gamma production by lymphocytes was markedly impaired. This is the first discovered human disease resulting from a cytokine gene defect. It suggests that IL-12 is essential to and appears specific for protective immunity to intracellular bacteria such as mycobacteria and salmonella.

Anti-B-cell monoclonal antibody treatment of severe posttransplant B-lymphoproliferative disorder: prognostic factors and long-term outcome

B-lymphoproliferative disorder (BLPD) is a rare but severe complication of organ and bone marrow transplantation (BMT). Profound cytotoxic T-cell deficiency is thought to allow the outgrowth of Epstein-Barr virus-transformed B cells. When possible, reduction of immunosuppressive treatment or surgery for localized disease may cure BLPD. Therapeutic approaches using chemotherapy or antiviral drugs have limited effects on survival. Adoptive immunotherapy with donor T-cell infusions has given promising results in BMT recipients. We previously reported that administration of two monoclonal anti-B-cell antibodies (anti-CD21 and anti-CD24) could contribute to the control of oligoclonal BLPD. Here we report the long-term results of treatment with these monoclonal anti-B-cell antibodies for cases of severe BLPD. In an open multicenter trial, 58 patients in whom aggressive B-cell lymphoproliferative disorder developed after BMT (n = 27) or organ (n = 31) transplantation received 0.2 mg/kg/d of specific anti-CD21 and anti-CD24 murine monoclonal antibodies (MoAbs) for 10 days. The treatment was well tolerated. Thirty-six of the 59 episodes of BLPD in the 58 patients presented complete remission (61%). The relapse rate was low (3 of 36, 8%). Multivariate analysis identified the following risk factors for partial or no response to anti-B-cell MoAb therapy: multivisceral disease (P </= .005), central nervous system involvement (P </= .05), and late onset of BLPD (P </= .005). The overall long-term survival was 46% (median follow-up, 61 months); it was lower among BMT patients (35%) than organ transplant patients (55%). None of the patients who had received BMT for hematological malignancy survived for 1 year. Eight of these 11 patients presented monoclonal BLPD. Tumor burden was the only other variable that contributed significantly to poor survival. Thus, as assessed from this long-term study, the use of anti-B-cell MoAbs therefore appears to be a safe and relatively effective therapy for severe posttransplant BLPD.

Normal CD40-mediated activation of monocytes and dendritic cells from patients with hyper-IgM syndrome due to a CD40 pathway defect in B cells

Patients with X-linked hyper-IgM syndrome [CD40 ligand (CD40L) deficiency] are prone to infections by intracellular parasites. It has been suggested that this susceptibility is caused by defective macrophage activation through the CD40L-CD40 pathway. We studied the CD40-mediated activation of monocytes and dendritic cells from patients affected with a CD40L+ hyper-IgM syndrome characterized by a defect of B lymphocyte responses to CD40 agonists. We show that the CD40-induced production of IL-6, IL-8 and TNF-alpha by monocytes, and IL-12 by dendritic cells, and expression of the activation markers CD83, the costimulatory molecules CD86 and CD80, and HLA-DR antigens were all similar in patient and control cells. This observation is consistent with the clinical characteristics of the syndrome: a defect of immunoglobulin switch but no susceptibility to opportunistic infections, as observed in CD40L-deficient patients. These observations suggest that CD40-mediated activation pathways could be, at least in part, different in B and monocytic/dendritic cell lineages.

Impairment of mycobacterial immunity in human interleukin-12 receptor deficiency

In humans, interferon gamma (IFN-gamma) receptor deficiency leads to a predisposition to mycobacterial infections and impairs the formation of mature granulomas. Interleukin-12 (IL-12) receptor deficiency was found in otherwise healthy individuals with mycobacterial infections. Mature granulomas were seen, surrounded by T cells and centered with epithelioid and multinucleated giant cells, yet reduced IFN-gamma concentrations were found to be secreted by activated natural killer and T cells. Thus, IL-12-dependent IFN-gamma secretion in humans seems essential in the control of mycobacterial infections, despite the formation of mature granulomas due to IL-12-independent IFN-gamma secretion.

[Therapeutic prospects and lymphoproliferative syndromes related to EBV]

The B lymphoproliferative disorders are a major (10%) and severe (70% mortality) complication of immunosuppression required for HLA-mismatched bone marrow or organ transplantation. An experimental model was developed in which patients infected EBV-B cells are inoculated into scid mice and develop into tumors, allowing evaluation of treatment efficacy: monoclonal antibodies directed to membrane antigens of tumoral cells (monoclonal antibodies anti-B), monoclonal antibodies neutralizing interleukins (and especially IL6), cytotoxic T cells. Results obtained with these three different approaches are herein reported.

Amino-acid change in the Epstein-Barr-virus ZEBRA protein in undifferentiated nasopharyngeal carcinomas from Europe and North Africa

Different Epstein-Barr-virus(EBV) variants were found to be associated with nasopharyngeal carcinoma (NPC). The type-C variant lacks the BamHI site between the BamHI W1* and I* regions and the type-f variant has an extra BamHI site in the BamHI F fragment. The BNLF1 gene (which encodes the LMP1 protein) from a nude-mouse-passaged CAO strain and from NPC biopsies from Taiwanese patients also exhibits variations resulting in structural and functional differences in the protein. The BZLF1 gene encodes the ZEBRA protein which triggers the EBV lytic cycle. A difference has been observed in 8 amino acids in the ZEBRA sequence in B95-8 (Z95) and P3HR1 (ZP3) cell lines. EBV found in NPC biopsies and peripheral-blood cells from Asians was predominantly of the ZP3 type (72%), while 81% of samples from different EBV-associated diseases and peripheral-blood cells from North Africa or Europe were of the Z95 type. We found that an alanine 206 had been replaced by a serine in the Z95 sequence in 72% of the NPC biopsies from European and North African patients. The Zser206 variant is found in a significantly lower percentage (p < 0.001) of other EBV-positive tissues from individuals in the same region (10-33%). In contrast, a 30-bp deletion is observed near the 3' end of the LMP1 gene in the majority of EBV (86%) from NPC and peripheral-blood cells from Asians, whereas a significantly lower percentage (p < 0.001) of NPC biopsies from European and North African patients (56%) have this deletion, as do lymphocytes from control individuals from the same region (36 and 55% respectively).

[Antiviral immunodeficiency: EBV, CMV, adenovirus]

Patients undergoing bone marrow transplantation are susceptible to many different bacterial, fungal and viral infections. Among the viral pathogens, cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus cause the greatest morbidity and mortality and have been the most common infectious causes of death following the grafting of allogeneic marrow. This great susceptibility to viral infections is due to the immunodeficiency in cellular and humoral immune responses lasting for months to years. Contributing factors are high-dose chemo/radiotherapy, graft-versus-host disease (GVHD) prophylaxis/treatment, GVHD itself, the degree of HLA disparity between donor and recipient and the underlying disease. Defects of T cell helper and cytotoxic functions contribute to the great incidence of viral infections. We described here the kinetic of immunological reconstitution and the role of T cell immunodeficiency. At day 30 to 40 after BMT, a minority of patients had recovery of virus-specific CD8+ T-cell response. Between day 40 and day 90 recovery of deficient CD8+ and CD4+ T cell responses occurred in the majority of the recipients of HLA identical BMT but only in the minority of the recipients of HLA partially incompatible BMT. New approaches should therefore be envisaged either to preserve donor T-cell-mediate immunity or tho accelerate immune reconstitution. Add-back of unmanipulated T-cells, or virus-specific T cells could improve antimicrobial defenses after BMT.

Epidermal Langerhans' cells in children with primary T-cell immune deficiencies

Dendritic cells are the major antigen-presenting cells, especially for naive T lymphocytes; it is conceivable therefore that their absence or dysfunction may induce an immune deficiency (ID). Few data are available, however, concerning dendritic cells in human primary ID. Langerhans' cells (LC) are intraepidermal dendritic cells which express specific markers and may therefore be studied by immunohistochemistry on paraffin-embedded skin samples. Skin samples of nine children with primary ID were studied and compared with five age-matched controls. LC were present within the epidermis of two children with X-linked severe combined ID, a condition related to the lack of the common gamma-chain of interleukin-2 (IL-2), IL-4, IL-7, IL-9, and IL-15 receptors. LC were also present in skin samples of a child with Omenn syndrome and in three children with combined ID. By contrast, no LC were detected in the skin samples of two children with alymphocytosis and of a child with reticular dysgenesis, a condition characterized by the absence of peripheral blood leukocytes.

Abnormal CD40-mediated activation pathway in B lymphocytes from patients with hyper-IgM syndrome and normal CD40 ligand expression

The CD40-mediated activation pathway of B cells from 10 patients with hyper-IgM syndrome and normal expression of CD40 ligand was studied. In all 10 cases, B cells were found to be defective for IgG, IgA, and IgE production after stimulation by anti-CD40 mAbs and cytokines. In the patients tested, neither B cell proliferation (n = 6) nor CD23 molecule expression (n = 5) were observed in cultures stimulated with anti-CD40 mAb. These results point to an intrinsic B cell deficiency and a defect in the CD40-triggered B cell activation pathway; this conclusion was supported by a lack of detectable germinal centers in the spleen of two patients. CD40-triggered activation events, i.e., phosphatidylinositol 3 (PI3) kinase activation and induction of transcription factors NF-kappaB and AP-1, were next analyzed in B cell lines derived from five patients. Three distinct patterns were observed: an absence of detectable abnormalities (n = 1), defective PI3 kinase activation with normal induction of NF-kappaB and AP-1 (n = 3), and defects in both PI3 kinase activation and induction of NF-kappaB and AP-1 (n = 1). In three B cell lines, each exhibiting one of the CD40-mediated activation patterns, sequences of CD40 and CD40 binding protein coding regions were normal. The coding region of TNF receptor-associated factor 2 (TRAF2), which is known to interact with CD40 for NF-kappaB induction, was also found to be normal in B cell lines deficient in NF-kappaB induction. Altogether, these results suggest that CD40 ligand-positive hyper-IgM syndrome could be genetically heterogeneous, although phenotypic variability is not excluded, and that an early defect in the CD40-triggered activation cascade can account for defective Ig class switching in some patients with CD40 ligand-positive hyper-IgM syndrome.

Abnormal CD40-mediated activation pathway in B lymphocytes from patients with hyper-IgM syndrome and normal CD40 ligand expression

The CD40-mediated activation pathway of B cells from 10 patients with hyper-IgM syndrome and normal expression of CD40 ligand was studied. In all 10 cases, B cells were found to be defective for IgG, IgA, and IgE production after stimulation by anti-CD40 mAbs and cytokines. In the patients tested, neither B cell proliferation (n = 6) nor CD23 molecule expression (n = 5) were observed in cultures stimulated with anti-CD40 mAb. These results point to an intrinsic B cell deficiency and a defect in the CD40-triggered B cell activation pathway; this conclusion was supported by a lack of detectable germinal centers in the spleen of two patients. CD40-triggered activation events, i.e., phosphatidylinositol 3 (PI3) kinase activation and induction of transcription factors NF-kappaB and AP-1, were next analyzed in B cell lines derived from five patients. Three distinct patterns were observed: an absence of detectable abnormalities (n = 1), defective PI3 kinase activation with normal induction of NF-kappaB and AP-1 (n = 3), and defects in both PI3 kinase activation and induction of NF-kappaB and AP-1 (n = 1). In three B cell lines, each exhibiting one of the CD40-mediated activation patterns, sequences of CD40 and CD40 binding protein coding regions were normal. The coding region of TNF receptor-associated factor 2 (TRAF2), which is known to interact with CD40 for NF-kappaB induction, was also found to be normal in B cell lines deficient in NF-kappaB induction. Altogether, these results suggest that CD40 ligand-positive hyper-IgM syndrome could be genetically heterogeneous, although phenotypic variability is not excluded, and that an early defect in the CD40-triggered activation cascade can account for defective Ig class switching in some patients with CD40 ligand-positive hyper-IgM syndrome.

Sensitivity of Epstein-Barr virus-induced B cell tumor to apoptosis mediated by anti-CD95/Apo-1/fas antibody

Epstein-Barr virus (EBV) can induce uncontrolled B lymphocyte proliferation leading to fatal lymphoma in immunocompromised patients. The sensitivity to apoptosis of B lymphoid cell lines (LCL) derived from EBV-induced lymphoproliferative disorders was investigated. In vitro and in vivo, these B LCL strongly express CD95/Apo-1/fas antigen and undergo apoptosis upon stimulation with anti-Apo-1 monoclonal antibody. When inoculated into severe-combined immunodeficient (scid) mice, human B cells lines developed into rapidly growing tumors. Administration of an agonistic anti-Apo-1 antibody significantly delayed tumor progression. Relapses were frequent, but were not caused by selection of resistant B cells, since B cells from relapsing tumors underwent apoptosis on re-exposure. Induction of apoptosis by an anti-C95/Apo-1/fas-specific antibody could be applied for therapy of EBV-induced B cell tumors and contribute to our understanding of the mechanisms of T cell-mediated elimination of EBV lymphomas in immunodeficient patients.

Production and roles of IL-6, IL-10, and IL-13 in B-lymphocyte malignancies and in B-lymphocyte hyperactivity of HIV infection and autoimmunity

We analyzed the production and the roles of IL-6, IL-10, and IL-13 in B-lymphoid malignancies and in specific diseases with B-lymphocyte hyperactivity. Both IL-13 and IL-10 genes are expressed in B-cell lymphomas. However, their contribution to tumor progression is unclear. In certain lymphoproliferative disorders that develop in transplanted patients, IL-6 is produced by malignant cells and is a major factor of their proliferation. In other lymphomas, the IL-6 gene is expressed only in malignancies where differentiated malignant cells are present. In these lymphomas, IL-6 is produced by stromal cells, and the malignant cells express the IL-6 receptor. In patients with HIV infection, the level of production of IL-6, IL-10, and IL-13 is not higher than those of other conditions with immune activation. However, IL-6 contributes to increased production of IgG and IgA in vivo. In Castleman's disease, IL-6 is produced in the lymph node germinal centers, partly originating from follicular dendritic cells, which may explain some of the pathogenesis of this disease. In systemic lupus erythematosus, the critical cytokine is IL-10, which is produced in large amounts by B lymphocytes and monocytes and is responsible for autoantibody production. Taken together, these data emphasize the roles of IL-6 and IL-10, usually produced by nonlymphoid cells, on B lymphocytes, either malignant or hyperactivated.

Hyper-IgM syndrome associated with rheumatoid arthritis: report of RA in a patient with primary impaired CD40 pathway

We studied a patient who had a typical seronegative rheumatoid arthritis (RA) and an immunodeficiency with hyper-IgM (HIM syndrome). CD40L was normally expressed by activated T cells, but CD40-mediated signal transduction was defective in B cells, preventing heavy chain switching (CD40L+ type of the HIM syndrome). These data suggest that a typical RA can develop in at least some patients with dysfunction of the CD40 pathway, i.e. in the absence of a normal co-operation between T and B cells. Accordingly, the blockade of CD40L-CD40 interactions, which has been proposed as a treatment of RA, might not be adapted to all patients.

Responses of T and B lymphocytes to a Paracoccidioides brasiliensis cell wall extract in healthy sensitized and nonsensitized subjects

Antigen-specific cellular immunity in paracoccidioidomycosis (PCM) has been poorly studied due to lack of standard in vitro lymphocyte proliferation assays. To standardize such an assay, we studied T and B cell responses to a Paracoccidioides brasiliensis cell wall extract (PbAg) in healthy subjects sensitized to either P. brasiliensis [Pb(+)Hc(-)] or to Histoplasma capsulatum [Hc(+)Pb(-)], and in nonsensitized persons. All subjects showed, as expected, a vigorous proliferative response to a control fungal antigen obtained from Candida albicans. Lymphocytes from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) donors, reacted to PbAg by proliferating in a dose-dependent manner with a maximum reaction after 6-9 days, suggesting a secondary specific immune response. Most activated cells were CD+CD4+ lymphocytes. However, Hc(+)Pb(-) donors' cells reacted with PbAg. Cross-reactivity with H. capsulatum was not unexpected, since both fungi, but not C. albicans, share cell wall immunogenic compounds. An enzyme-linked immunosorbent assay to detect human immunoglobulins (Ig) demonstrated that B cells from Pb(+)Hc(-) donors, but not from Pb(-)Hc(-) ones, reacted with PbAg by secreting high levels of IgG and IgM in 12-day culture supernatants. This secretion was possibly mediated by PbAg-activated CD4+ cells. We believe that analysis of T and B lymphocyte responses to PbAg will be useful in the investigation of the infection-associated immune impairment seen in some PCM patients.

Recombinant soluble trimeric CD40 ligand is biologically active

CD40 ligand (CD40L) is expressed on the surface of activated CD4+ T cells, basophils, and mast cells. Binding of C40L to its receptor, CD40, on the surface of B cells stimulates B cell proliferation, adhesion and differentiation. A preparation of soluble, recombinant CD40L (Tyr-45 to Leu-261), containing the full-length 29-kDa protein and two smaller fragments of 18 and 14 kDa, has been shown to induce differentiation of B cells derived either from normal donors or from patients with X-linked hyper-IgM syndrome (Durandy, A., Schiff, C., Bonnefoy, J.-Y., Forveille, M., Rousset, F., Mazzei, G., Milili, M., and Fischer, A. (1993) Eur. J. Immunol. 23, 2294-2299). We have now purified each of these fragments to homogeneity and show that only the 18-kDa fragment (identified as Glu-108 to Leu-261) is biologically active. When expressed in recombinant form, the 18-kDa protein exhibited full activity in B cell proliferation and differentiation assays, was able to rescue of B cells from apoptosis, and bound soluble CD40. Sucrose gradient sedimentation shows that the 18-kDa protein sediments as an apparent homotrimer, a result consistent with the proposed trimeric structure of CD40L. This demonstrates that a soluble CD40L can stimulate CD40 in a manner indistinguishable from the membrane-bound form of the protein.

Undetectable CD40 ligand expression on T cells and low B cell responses to CD40 binding agonists in human newborns

IgG, IgA, and IgE production by newborn B cells is limited both in vivo and in vitro in various activation conditions, whereas IgM production is readily detectable. It has been suggested that the Ig heavy chain switch inability could be the consequence of T and B cell immaturity. As the interaction between CD40 (expressed on B cells) and its ligand CD40-L (expressed on activated T cells) triggers a key signal required for isotype switching, we studied the expression and function of these two components in normal fetuses, newborns, and infants, compared with adults. CD40-L expression was not inducible in 28 of 30 specimens of newborn cord-blood T cells following incubation with PMA and ionomycin, whereas activation markers such as CD69 were inducible. CD40-L expression was triggered by activation of T cells from infants > 3 wk of age. Surprisingly, T cells from 19- to 28-wk-old fetuses also expressed CD40-L following activation. CD40-L expression on newborn T lymphocytes was induced on T cell lines generated in the presence of PHA and maintained with IL-2 following further stimulation with PMA and ionomycin. CD40-L mRNA transcripts and intracytoplasmic protein expression following activation of newborn T cells were strongly decreased, leading to undetectable protein membrane detection. These results point to a possible transcriptional down-regulation of CD40-L expression by neonatal T lymphocytes. In addition, fetal and cord-blood B cells were poorly able to switch to IgG or IgA by stimulation with CD40 agonists (Ab or soluble CD40-L) in the presence of IL-4 or IL-10 as also detected with surface IgD+ adult B cells. Both phenomena could contribute to the neonatal Ig switch inability, although distinct underlying regulatory mechanisms are probably involved, as suggested by different in vivo time courses.

Undetectable CD40 ligand expression on T cells and low B cell responses to CD40 binding agonists in human newborns

IgG, IgA, and IgE production by newborn B cells is limited both in vivo and in vitro in various activation conditions, whereas IgM production is readily detectable. It has been suggested that the Ig heavy chain switch inability could be the consequence of T and B cell immaturity. As the interaction between CD40 (expressed on B cells) and its ligand CD40-L (expressed on activated T cells) triggers a key signal required for isotype switching, we studied the expression and function of these two components in normal fetuses, newborns, and infants, compared with adults. CD40-L expression was not inducible in 28 of 30 specimens of newborn cord-blood T cells following incubation with PMA and ionomycin, whereas activation markers such as CD69 were inducible. CD40-L expression was triggered by activation of T cells from infants &gt; 3 wk of age. Surprisingly, T cells from 19- to 28-wk-old fetuses also expressed CD40-L following activation. CD40-L expression on newborn T lymphocytes was induced on T cell lines generated in the presence of PHA and maintained with IL-2 following further stimulation with PMA and ionomycin. CD40-L mRNA transcripts and intracytoplasmic protein expression following activation of newborn T cells were strongly decreased, leading to undetectable protein membrane detection. These results point to a possible transcriptional down-regulation of CD40-L expression by neonatal T lymphocytes. In addition, fetal and cord-blood B cells were poorly able to switch to IgG or IgA by stimulation with CD40 agonists (Ab or soluble CD40-L) in the presence of IL-4 or IL-10 as also detected with surface IgD+ adult B cells. Both phenomena could contribute to the neonatal Ig switch inability, although distinct underlying regulatory mechanisms are probably involved, as suggested by different in vivo time courses.

Partial albinism with immunodeficiency (Griscelli syndrome)

Partial albinism with immunodeficiency is a rare and fatal immunologic disorder characterized by pigmentary dilution and variable cellular immunodeficiency. To define the phenotype, therapy, and outcome, we retrospectively analyzed seven consecutive patients. Primary abnormalities included a silvery-grayish sheen to the hair, large pigment agglomerations in hair shafts, and an abundance of mature melanosomes in melanocytes, with reduced pigmentation of adjacent keratinocytes. Clinical onset occurred between the ages of 4 months and 4 years and was characterized by accelerated phases (lymphohistiocytic infiltration of multiple organs, including the brain and the meninges), triggered by viral and bacterial infections. Characteristic laboratory features included pancytopenia, hypofibrinogenemia, hypertriglyceridemia, and hypoproteinemia. Consistent immunologic abnormalities were characterized by absent delayed-type cutaneous hypersensitivity and impaired natural killer cell function. Some patients had secondary hypogammaglobulinemia, impaired major histocompatibility complex-mediated cytotoxic effects, a decreased capacity of lymphocytes to trigger a mixed lymphocyte reaction, or various functional granulocytic abnormalities. The disease seems to be invariably lethal without bone marrow transplantation; the mean age at the time of death was 5 years. Bone marrow transplantation has been performed in three cases; two patients died in the immediate posttransplantation period of infectious complications, but one patient is cured after a follow-up of 5 years. We conclude that partial albinism with immunodeficiency (Griscelli syndrome) can be differentiated from Chédiak-Higashi syndrome by pathognomonic histologic features. One of the underlying immunologic defects may be a defective function of natural killer cells, predisposing the patient to virus-associated hemophagocytic syndrome or accelerated phases. The prognosis is very poor unless early bone marrow transplantation is carried out.

T cell clones from an X-linked hyper-immunoglobulin (IgM) patient induce IgE synthesis in vitro despite expression of nonfunctional CD40 ligand

The induction of immunoglobulin E (IgE) switching in B cells requires at least two signals. The first is given by either of the soluble lymphokines interleukin 4 (IL-4) or IL-13, whereas the second is contact dependent. It has been widely reported that a second signal can be provided by the CD40 ligand (CD40L) expressed on the surface of T cells, mast cells, and basophils. A defect in the CD40L has been shown recently to be responsible for the lack of IgE, IgA, and IgG, characteristic of the childhood X-linked immunodeficiency, hyper IgM syndrome (HIGM1). IgE can however be detected in the serum of some HIGM1 patients. In this study, we isolated T cell clones and lines using phytohemagglutinin (PHA) and allergen, respectively, from the peripheral blood of one such patient who expressed a truncated form of CD40L, and investigated their ability to induce IgE switching in highly purified, normal tonsillar B cells in vitro. Unexpectedly, 4 of 12 PHA clones tested induced contact-dependent IgE synthesis in the presence of exogenous IL-4. These clones were also shown to strongly upregulated IL-4-induced germline epsilon RNA and formed dense aggregates with B cells. Of the four helper clones, three were CD8+, of which two were characteristic of the T helper cell 2 (Th2) subtype. Two allergen-specific HIGM1 T cell lines, both of the Th0 subtype, could also drive IgE synthesis when prestimulated using specific allergen. All clones and lines were negative for surface expression of CD40L, and the mutated form of CD40L was confirmed for a representative clone by RNase protection assay and sequencing. The IgE helper activity could not be attributed to membrane tumor necrosis factor alpha (TNF-alpha) although it was strongly expressed on activated clones, and the addition of neutralizing anti-TNF-alpha antibody did not abrogate IgE synthesis. These results therefore suggest the involvement of T cell surface molecules other than CD40L in the induction of IgE synthesis, and that these molecules may also be implicated in other aspects of T-B cell interactions.

Role of IL-6 in promoting growth of human EBV-induced B-cell tumors in severe combined immunodeficient mice

To investigate the role of IL-6 as a growth factor in EBV-induced B lymphoproliferative disorders in immune-suppressed patients, we analyzed two B cell lines derived from two different patients for IL-6 production, expression of the p80 chain of the IL-6 receptor, and the effects on cell growth in vitro and in vivo of neutralizing mAbs specific for IL-6. One of the cell lines (LCL41) was shown to produce large amounts of IL-6 and to express IL-6 receptors. Its in vitro growth was weakly inhibited by the anti-IL-6 MAb. After inoculation into SCID mice, this cell line provoked human B cell tumors, the growth of which was controlled by the anti-IL-6 mAb. Indeed, four i.v. infusions of 0.1 mg at days 30 to 42 after i.p. inoculation of cells led to complete remission in most mice and long term survival in 40% of cases. In contrast, the other B cell line (LCL48) produced smaller amounts of IL-6; its growth was not inhibited in vitro by the anti-IL-6 Ab and was poorly blocked in vivo in SCID mice (40% of remissions and 20% of long-term survival). In addition, a clone derived in vivo in SCID mice from LCL48 was completely IL-6-independent. These results demonstrate that B cell tumors transformed in vivo by EBV in immune-suppressed patients are heterogeneous with respect to IL-6 requirements for proliferation. An antitumoral effect in some of them can be achieved by neutralizing the IL-6-dependent proliferative loop.

Severe acute paracoccidioidomycosis in children

This report describes clinical and immunologic features of five illustrative cases of paracoccidioidomycosis in previously healthy children. All had disseminated disease and two of them died despite treatment. The major clinical presentation in four patients was fever and diffuse superficial and intraabdominal adenopathy, with or without hepatosplenomegaly. Other sites were also affected: three patients had multiple osteoarticular lesions, occasionally with intense tissue destruction; two had cutaneous eruptions; two had pericardial effusions; and two had pulmonary involvement, once considered an organ spared in the young. We detected variable lymphocyte responses to mitogens and to Candida albicans antigen and non-responsiveness to Paracoccidioides brasiliensis cell wall antigen. High concentrations of serum immunoglobulins and anti-P. brasiliensis antibodies were present. These immune alterations tended to resolve with treatment, suggesting a reversible nature of the immune defect. We conclude that this mycosis has a high morbidity and mortality in children, which is probably related to an antigen-specific immunodeficiency. Further studies are needed to increase knowledge of this mycosis in children.

Role of IL-6 in promoting growth of human EBV-induced B-cell tumors in severe combined immunodeficient mice

To investigate the role of IL-6 as a growth factor in EBV-induced B lymphoproliferative disorders in immune-suppressed patients, we analyzed two B cell lines derived from two different patients for IL-6 production, expression of the p80 chain of the IL-6 receptor, and the effects on cell growth in vitro and in vivo of neutralizing mAbs specific for IL-6. One of the cell lines (LCL41) was shown to produce large amounts of IL-6 and to express IL-6 receptors. Its in vitro growth was weakly inhibited by the anti-IL-6 MAb. After inoculation into SCID mice, this cell line provoked human B cell tumors, the growth of which was controlled by the anti-IL-6 mAb. Indeed, four i.v. infusions of 0.1 mg at days 30 to 42 after i.p. inoculation of cells led to complete remission in most mice and long term survival in 40% of cases. In contrast, the other B cell line (LCL48) produced smaller amounts of IL-6; its growth was not inhibited in vitro by the anti-IL-6 Ab and was poorly blocked in vivo in SCID mice (40% of remissions and 20% of long-term survival). In addition, a clone derived in vivo in SCID mice from LCL48 was completely IL-6-independent. These results demonstrate that B cell tumors transformed in vivo by EBV in immune-suppressed patients are heterogeneous with respect to IL-6 requirements for proliferation. An antitumoral effect in some of them can be achieved by neutralizing the IL-6-dependent proliferative loop.

Severe combined immunodeficiency: a retrospective single-center study of clinical presentation and outcome in 117 patients

We carried out a retrospective analysis of 117 patients with severe combined immunodeficiency who were examined in a single center between Jan. 1, 1970, and Jan. 1, 1992, for the purpose of evaluating disease onset, progression, and outcome. The frequency of case referral increased from 8 from 1970 to 1975 to 56 from 1986 to 1991. The most frequent phenotype was T-/B+ (absence of T lymphocytes and presence of B lymphocytes) (n = 51); there were 36 cases of alymphocytosis, 16 of adenosine deaminase deficiency, 13 of Omenn syndrome, and 1 of reticular dysgenesis. Protracted diarrhea and lung infections were the main infectious complications; infection with bacillus Calmette-Guérin occurred in 10 of 28 vaccinated patients, but none of the six recipients of oral polio vaccine subsequently had poliomyelitis. The presence of maternal T cells was suspected or proved in half the patients with alymphocytosis or T-B+ severe combined immunodeficiency but did not occur in the other forms of the disease. Of the 117 patients, 22 died before transplantation could be performed. Adenosine deaminase deficiency and Omenn syndrome were more frequently associated with death before hematopoietic stem cell transplantation was possible. Fetal liver transplantation was successful in 1 of 10 cases. The survival rate among the 30 recipients of bone marrow with identical human leukocyte antigens (HLA) was 80%, with a median follow-up of 129 months; 23 of 25 patients recovered full immune function. The survival rate among the 50 recipients of HLA-haploidentical T cell-depleted bone marrow was 56%, with a mean follow-up of 35 months. Of the latter patients, 10 (35%) still require immunoglobulin substitution. There has been a trend toward improvement in the survival rate of haploidentical bone marrow recipients, presumably because of more effective infection-control measures and better transplantation strategy.

Induction by anti-CD40 antibody or soluble CD40 ligand and cytokines of IgG, IgA and IgE production by B cells from patients with X-linked hyper IgM syndrome

We studied the ability of B lymphocytes from patients with X-linked hyper IgM syndrome (HIGM1) to be activated via the CD40 membrane receptor. HIGM1 is caused by a CD40 ligand gene mutation, leading to defective expression on the membrane of activated T lymphocytes. We found that triggering of B cells by an anti-CD40 monoclonal antibody or the soluble CD40 ligand plus interleukin (IL)-4 or IL-10 led to B cell proliferation and/or differentiation towards IgG, IgA and IgE secretion. This was reflected by transcription of C gamma, alpha and epsilon membrane isotype expression and IgG, IgA and IgE production. These results confirm the integrity of B cells in patients with the HIGM1 immunodeficiency and open up new therapeutic possibilities.