7th International Immunoglobulin Conference: Immunodeficiencies

Most primary immunodeficiency disorders (PID) are the result of single gene defects. Based on this fact, more than 240 different entities have been identified. Those PIDs with predominant antibody deficiency are treated with immunoglobulin (Ig) replacement therapy. This review focuses on the diagnosis, clinical characteristics and treatment of patients suffering from PID, or secondary immunodeficiency disorders (SID) caused, for instance, by irradiation, immunosuppressive drugs or thymectomy. Common variable immunodeficiency (CVID) is the most commonly diagnosed and least understood form of PID, with a heterogeneous range of symptoms and genotypes, requiring individualized treatment plans. This includes adjusting the dose and treatment interval, administrating Ig by intravenous or subcutaneous injection by either pump or push, and finally deciding which treatment options are best for a given patient. Ig therapy can also be used to treat immunodeficiencies resulting from lymphoproliferative and autoimmune diseases or immunosuppression following organ transplantation; however, there is an urgent need for research in this field. Accurate and early diagnosis of PID is important to ensure that optimal treatment is started early to maintain the patient's health. Detailed patient registries have been established to increase awareness of PID, as well as provide a valuable resource for further research.

7th International Immunoglobulin Conference: Immunodeficiencies

Awareness of the challenges involved in diagnosing and treating a heterogeneous group of immunodeficiency disorders is growing. The improvements in neonatal screening offer new methods to ensure that primary immunodeficiencies (PIDs) are diagnosed as early as possible, enabling accurate treatment and the prevention of life-threatening infections and other complications. Additionally, the need to individualize patient therapy in order to optimize both clinical outcomes and quality-of-life is obvious and is exemplified by the ability to switch between intravenous and subcutaneous immunoglobulin administration offering flexible treatment regimens. However, further research is crucial in order to determine the optimal treatment for secondary immunodeficiencies, and to gain greater understanding of the underlying causes of PIDs, including common variable immunodeficiency. The information relating to the growth of patient registries is encouraging, with approximately 25 000 patients with PIDs included in the two registries discussed. Registries such as this are vital for future research, as well as providing an educational resource.

Efficacy and safety of home-based subcutaneous immunoglobulin replacement therapy in paediatric patients with primary immunodeficiencies

Subcutaneous immunoglobulin infusions are effective, safe and well tolerated in the treatment of primary immunodeficiencies, but only limited data on the treatment of children are available. We investigated the efficacy, safety and pharmacokinetics of home therapy with a 16% liquid human immunoglobulin G preparation (Vivaglobin®) when administered subcutaneously in children with primary immunodeficiencies. Data were analysed from 22 children (2-<12 years) who participated in two prospective, open-label studies (one in Europe/Brazil, one in North America). All children had previously received intravenous immunoglobulins. They started weekly subcutaneous immunoglobulin infusions with an approximately 3-month wash-in/wash-out period, followed by a 6-month (Europe/Brazil) or 12-month (North America) efficacy evaluation period. In Europe/Brazil, subcutaneous doses generally equalled the previous weekly equivalent intravenous doses. In North America, subcutaneous doses during the efficacy evaluation period were 126% (median) of the previous weekly equivalent intravenous doses. Efficacy end-points in both studies included the occurrence of serious bacterial infections and any infections, and serum immunoglobulin G trough levels. Median serum immunoglobulin G trough levels exceeded those during previous intravenous therapy by 13% (North America) and 16% (Europe/Brazil). During the efficacy evaluation period of both studies, none of the children had a serious bacterial infection; the mean overall infection rate/patient year was 4·7 in Europe/Brazil and 5·6 in North America, concurring with previous reports in adults. The adverse event profile was comparable to previous reports in adults. Both studies confirmed the efficacy and safety of subcutaneous immunoglobulin therapy with Vivaglobin in children with primary immunodeficiencies.

Immunodeficiencies

Primary immunodeficiencies (PIDs) are uncommon, chronic and severe disorders of the immune system in which patients cannot mount a sufficiently protective immune response, leading to an increased susceptibility to infections. The treatment of choice for PID patients with predominant antibody deficiency is intravenous immunoglobulin (Ig) replacement therapy. Despite major advances over the last 20 years in the molecular characterization of PIDs, many patients remain undiagnosed or are diagnosed too late, with severe consequences. Various strategies to ensure timely diagnosis of PIDs are in place, and novel approaches are being developed. In recent years, several patient registries have been established. Such registries shed light on the pathology and natural history of these varied disorders. Analyses of the registry data may also reveal which patients are likely to respond well to higher Ig infusion rates and may help to determine the optimal dosing of Ig products. Faster infusion rates may lead to improved convenience for patients and thus increase patient compliance, and may reduce nursing time and the need for hospital resources. Data from two recent studies suggest that Gamunex and Privigen are well tolerated at high infusion rates. Nevertheless, careful selection of patients for high infusion rates, based on co-morbid conditions and tolerance of the current infusion rate, is advisable. Based on the available data, intravenous Ig offers broad protection against encapsulated organisms. As vaccine trends change, careful monitoring of specific antibody levels in the general population, such as those against pneumococcal and meningococcal bacteria, should be implemented.

Subcutaneous immunoglobulin: opportunities and outlook

Immunoglobulin (Ig) administration via the subcutaneous (s.c.) route has become increasingly popular in recent years. The method does not require venous access, is associated with few systemic side effects and has been reported to improve patients' quality of life. One current limitation to its use is the large volumes which need to be administered. Due to the inability of tissue to accept such large volumes, frequent administration at multiple sites is necessary. Most studies conducted to date have investigated the use of subcutaneous immunoglobulin (SCIg) in patients treated previously with the intravenous (i.v.) formulation. New data now support the use of s.c. administration in previously untreated patients with primary immunodeficiencies. SCIg treatment may further be beneficial in the treatment of autoimmune neurological conditions, such as multi-focal motor neuropathy; however, controlled trials directly comparing the s.c. and i.v. routes are still to be performed for this indication. New developments may further improve and facilitate the s.c. administration route. For example, hyaluronidase-facilitated administration increases the bioavailability of SCIg, and may allow for the administration of larger volumes at a single site. Alternatively, more concentrated formulations may reduce the volume required for administration, and a rapid-push technique may allow for shorter administration times. As these developments translate into clinical practice, more physicians and patients may choose the s.c. administration route in the future.

Primary immune deficiency disorders presenting as autoimmune diseases: IPEX and APECED

BACKGROUND

Several primary immune deficiency disorders are associated with autoimmunity and malignancy, suggesting a state of immune dysregulation. The concept of immune dysregulation as a direct cause of autoimmunity in primary immune deficiency disorders (PIDDs) has been strengthened by the recent discovery of distinct clinical entities linked to single-gene defects resulting in multiple autoimmune phenomena including immune dysregulation, polyendocrinopathy, enteropathy and X-linked (IPEX) syndrome, and autoimmune polyendocrinopathy, candidiasis and ectodermal dystrophy (APECED) syndrome.

CONCLUSION

Reviewing recent advances in our understanding of the small subgroup of PIDD patients with defined causes for autoimmunity may lead to the development of more effective treatment strategies for idiopathic human autoimmune diseases.

Intensive postgrafting immune suppression combined with nonmyeloablative conditioning for transplantation of HLA-identical hematopoietic cell grafts: results of a pilot study for treatment of primary immunodeficiency disorders

This study was designed to determine the safety of a nonmyeloablative regimen in patients with primary immunodeficiency disorders (PID) who had infections, organ dysfunction or other risk factors that precluded conventional hematopoietic cell (HC) transplant. Fourteen patients received HLA-matched related (n=6) or unrelated (n=8) HC grafts from marrow (n=8), peripheral blood mononuclear cells (n=5) or umbilical cord blood (n=1), either without conditioning (n=1), or after 200 cGy total body irradiation alone (n=3) or with 90 mg/m2 fludarabine (n=10). All patients were given postgrafting immunosuppression with mycophenolate mofetil and cyclosporine. Mixed (n=5) or full (n=8) donor chimerism was established in 13 patients, and one patient rejected the graft. Eight patients developed acute grade III (n=1) and/or extensive chronic GVHD (n=8). With a median follow-up of 4.9 (range, 0.7-8.1) years, the 3-year overall survival, event-free survival and transplant-related mortality were 62, 62 and 23%, respectively. Correction of immune dysfunction was documented in 8 of 10 patients with stable donor engraftment. These preliminary results indicated that this approach was associated with stable donor engraftment and a low incidence of early mortality and, thus, can be considered for certain high-risk patients with PID. However, there was a risk of GVHD, which is an undesirable outcome for this group of patients.

Classification of mutations in the human CD40 ligand, gp39, that are associated with X-linked hyper IgM syndrome

The interaction between the T cell activation antigen gp39 and CD40, its receptor CD40 on B cells, plays a critical role in the regulation of humoral immune responses. Using a detailed three-dimensional model of the gp39 extracellular region, we have analyzed 20 mutations in gp39 that were, with one exception, isolated from patients with X-linked hyper IgM (XHIM) syndrome. On the basis of this analysis, the mutations were classified according to their predicted locations and effects. Twelve mutations are thought to compromise the gp39 structure by affecting interactions in hydrophobic core regions or at monomer interfaces, whereas seven others map closely to gp39 residues important for interaction with CD40. The latter mutations may thus, directly or indirectly, interfere with CD40 binding. One naturally occurring mutant whose carrier displays normal immune responses maps to a solvent-exposed position in a loop region of the molecule.

Inhaled IFN-gamma for persistent nontuberculous mycobacterial pulmonary disease due to functional IFN-gamma deficiency

Pulmonary infection with nontuberculous mycobacteria (NTM) in previously healthy human immunodeficiency virus-seronegative individuals is difficult to treat. Recently, functional interferon (IFN)-gamma deficiency has been identified in individuals susceptible to this disease. Treatment with inhaled IFN-gamma for NTM pulmonary disease associated with functional IFN-gamma deficiency has not been previously described. In this study, the IFN-gamma pathway was characterised in an individual who had progressive NTM pulmonary infection, despite appropriate multidrug antibiotic therapy, and 10 healthy controls. Levels of IFN-gamma and tumour necrosis factor-alpha in whole blood were assessed before and after incubation with lipopolysaccharide, heat-killed Escherichia coli, heat-killed Staphylococcus aureus and phorbol myristate acetate/ionomycin. The coding regions of interleukin (IL)-12, IL-18 and the IL-12 receptor were sequenced using nested primers. IFN-gamma1b (100 microg.dose(-1)) was administered to the affected individual by ultrasonic nebuliser 3 days.week(-1) for 3 months. In vitro whole blood production of IFN-gamma with and without physiological stimuli was consistent with functional IFN-gamma deficiency in the affected individual. There was no evidence of mutation in the coding regions of IL-12p35, IL-12p40, IL-12Rbeta1 and IL-18 in the affected individual. Treatment with inhaled IFN-gamma resulted in rapid and sustained clearance of the organism from the airways and stabilisation of lung function. In conclusion, inhaled interferon-gamma can be effective for the treatment of nontuberculous mycobacteria pulmonary disease associated with functional interferon-gamma deficiency.

Pharmacokinetics and tolerability of a new intravenous immunoglobulin preparation, IGIV-C, 10% (Gamunex, 10%)

BACKGROUND AND OBJECTIVES

A new intravenous immunoglobulin (IGIV) process has been developed that integrates efficient inactivation of enveloped virus, using caprylate, with immunoglobulin G (IgG) purification and caprylate removal by column chromatography. Two clinical studies were conducted to compare the pharmacokinetics of the new product, IGIV-C, 10% (Gamunex, 10%), formulated with glycine, with the licensed solvent-detergent (SD)-treated intravenous immunoglobulin IGIV-SD, 10% (Gamimune N, 10%), formulated with glycine, and IGIV-C, 5%, formulated with 10% maltose.

MATERIALS AND METHODS

Both studies were randomized, multicentre crossover trials of 18 and 20 (respectively) adult patients with primary humoral immune deficiency in which patients received one IGIV product for three consecutive periods (3-4 weeks) before crossing over to the other product. Pharmacokinetic parameters were determined after the third infusion of each product.

RESULTS

IGIV-C, 10% was bioequivalent to IGIV-SD, 10%, with half-lives (t1/2) of 35 and 34 days, respectively. IGIV-C, 5%, was bioequivalent to IGIV-C, 10%, with t1/2 of 35 and 36 days, respectively. The products had comparable safety profiles.

CONCLUSIONS

The pharmacokinetic profiles observed in these trials indicate that IGIV-C, 10% may replace, and be administered in a manner similar to, IGIV-SD, 10%.

IPEX is a unique X-linked syndrome characterized by immune dysfunction, polyendocrinopathy, enteropathy, and a variety of autoimmune phenomena

The rare syndrome known as IPEX (OMIM: 304930) is characterized by immune-dysfunction, polyendocrinopathy, enteropathy, and X-linked inheritance. The gene responsible for IPEX maps to Xp11.23-q13.3, a region of the X chromosome that also harbors the Wiskott-Aldrich syndrome gene ( WASP ). IPEX syndrome results from mutations of a unique DNA binding protein gene, FOXP3. Mutations invariably impair the seemingly essential forkhead domain of the protein, which is uniquely located in the carboxyl terminus, affecting protein function. In this review, we describe the identification of IPEX as a unique X-linked syndrome, the clinical features of IPEX, mutations of the immune-specific FOXP3 DNA binding protein, and bone marrow transplantation as a potential cure for the syndrome, which is usually lethal within the first year of life in affected males.

Lymphocyte proliferation is associated with gender, caregiving, and psychosocial variables in older adults

We examined lymphocyte responses to mitogens [phytohemagglutinin (PHA), concanavalin A, pokeweed] in spouse caregivers of persons with Alzheimer's disease (n = 82; mean age = 69.4) and noncaregiver spouses (n = 83) group matched on age and gender. Data were collected at study entry (T1) and 15-18 months later (T2). In men (n = 52), a depressed mood factor was negatively related to all mitogen responses at T1 and PHA at T2. Loneliness was the most important variable in the depressed mood factor. No relationships occurred in women (n = 113). At T2 an anger expression factor (anger-out--anger-control) was negatively related to all mitogen responses in caregivers. Anger-out was the most important variable for anger expression. Depressed mood at T1 predicted residualized changes in PHA at T2 in men. In conclusion, men with higher depressed mood and caregivers with higher anger expression may be at risk for lower proliferation responses.

Bruton's tyrosine kinase is a substrate of calpain in human platelets

Platelet-associated Bruton's tyrosine kinase (Btk) was completely cleaved if treated with calcium ionophore A23187 with appearance of a proteolytic product of 27 kDa size. Aggregation with thrombin also induced about 10% degradation of Btk after 30 min. Calpain inhibitors prevented Btk degradation in both. The proteolytic products of the Wiskott-Aldrich syndrome protein (WASP), a calpain and Btk substrate, and the 27 kDa degradation product of Btk did not redistribute to the Triton-insoluble cytoskeleton in thrombin-aggregated platelets, in contrast to the uncleaved proteins. The degradation of Btk and WASP was independent of their tyrosine phosphorylation status. These results indicate that Btk is an endogenous substrate for calpain, the cleavage of which may have functional consequences in long-term post-aggregation events in platelets.

Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency characterized by thrombocytopenia with small platelets, eczema, recurrent infections, autoimmune disorders, IgA nephropathy, and an increased incidence of hematopoietic malignancies. The identification of the responsible gene, WASP (Wiskott-Aldrich Syndrome Protein), revealed clinical heterogeneity of the syndrome, and showed that X-linked thrombocytopenia without, or with only mild immunodeficiency and eczema, is also caused by mutations of WASP. The study of WASP and its mutations demonstrates how a single gene defect can cause multiple and complex clinical symptoms.

The mutational spectrum of human malignant autosomal recessive osteopetrosis

Human malignant infantile osteopetrosis (arOP; MIM 259700) is a genetically heterogeneous autosomal recessive disorder of bone metabolism, which, if untreated, has a fatal outcome. Our group, as well as others, have recently identified mutations in the ATP6i (TCIRG1) gene, encoding the a3 subunit of the vacuolar proton pump, which mediates the acidification of the bone/osteoclast interface, are responsible for a subset of this condition. By sequencing the ATP6i gene in arOP patients from 44 unrelated families with a worldwide distribution we have now established that ATP6i mutations are responsible for approximately 50% of patients affected by this disease. The vast majority of these mutations (40 out of 42 alleles, including seven deletions, two insertions, 10 nonsense substitutions and 21 mutations in splice sites) are predicted to cause severe abnormalities in the protein product and are likely to represent null alleles. In addition, we have also analysed nine unrelated arOP patients from Costa Rica, where this disease is apparently much more frequent than elsewhere. All nine Costa Rican patients bore either or both of two missense mutations (G405R and R444L) in amino acid residues which are evolutionarily conserved from yeast to humans. The identification of ATP6i gene mutations in two families allowed us for the first time to perform prenatal diagnosis: both fetuses were predicted not to be affected and two healthy babies were born. This study contributes to the determination of genetic heterogeneity of arOP and allows further delineation of the other genetic defects causing this severe condition.

Carrier-mediated enhancement of cognate T cell help: the basis for enhanced immunogenicity of meningococcal outer membrane protein polysaccharide conjugate vaccine

Haemophilus influenzae type b capsular polysaccharide (PRP) conjugate vaccines, which are thought to induce T cell-dependent antibody production, induce protective responses after a single dose in individuals under 15 months of age. However, multiple doses of these vaccines are required to induce protective antibody responses in infants, with the exception of PRP conjugated to meningococcal outer membrane proteins (OMPC), which does so after a single dose. The basis for this difference is not fully understood, although others have proposed that OMPC and porins, the major protein component of OMPC, act as adjuvants or mitogens. In this report OMPC is shown to enhance CD40 ligand-mediated, T cell-dependent antibody production in mice. This paralleled the induction by OMPC of CD86, CD80 and CD40 costimulatory molecules on human neonatal and murine B cells and of Th1 cytokines. Neither porins nor lipopolysaccharide fully reproduced the effects of OMPC. These studies indicate that OMPC acts both as carrier and adjuvant, and thereby enhances T cell-dependent antibody responses in human infants.

A rare polyadenylation signal mutation of the FOXP3 gene (AAUAAA-->AAUGAA) leads to the IPEX syndrome

The mouse scurfy gene, Foxp3, and its human orthologue, FOXP3, which maps to Xp11.23-Xq13.3, were recently identified by positional cloning. Point mutations and microdeletions of the FOXP3 gene were found in the affected members of eight of nine families with IPEX (immune dysfunction, polyendocrinopathy, enteropathy, X-linked; OMIM 304930). We evaluated a pedigree with clinically typical IPEX in which mutations of the coding exons of FOXP3 were not detected. Our reevaluation of this pedigree identified an A-->G transition within the first polyadenylation signal (AAUAAA-->AAUGAA) after the stop codon. The next polyadenylation signal is not encountered for a further 5.1 kb. This transition was not detected in over 212 normal individuals (approximately 318 X chromosomes), excluding the possibility of a rare polymorphism. We suggest that this mutation is causal of IPEX in this family by a mechanism of nonspecific degradation of the FOXP3 gene message.

Long-term low-dose IL-2 enhances immune function in common variable immunodeficiency

Common variable immunodeficiency (CVID) is a primary immunodeficiency disease characterized by hypogammaglobulinemia and lack of antibody production. Numerous T cell defects have been described, including reduced gene expression and production of IL-2. Since some of the T cell defects could be explained by lack of IL-2, we have been investigating the effects of in vivo IL-2 treatment. Here, a long-acting form of IL-2, PEG-IL-2, was given for 12-18 months to 15 randomly chosen CVID subjects, in comparison to 39 CVID subjects who served as controls. After 6 to 12 months of treatment, T cell proliferative responses to mitogens and to IL-2 were significantly enhanced; proliferative responses to tetanus and candida antigens increased up to 50-fold. Four of eight subjects immunized with the neoantigen bacteriophage &phi;X 174 displayed increased antibody responses after treatment. Treated subjects recorded reduced, but not overall statistically significant, days of bronchitis, diarrhea, and joint pain. These data indicate that IL-2 might serve as an adjuvant to therapy in some subjects with CVID, enhancing T cell functions and reversing T cell anergy in most.

Somatic mosaicism in Wiskott--Aldrich syndrome suggests in vivo reversion by a DNA slippage mechanism

Somatic mosaicism caused by in vivo reversion of inherited mutations has been described in several human genetic disorders. Back mutations resulting in restoration of wild-type sequences and second-site mutations leading to compensatory changes have been shown in mosaic individuals. In most cases, however, the precise genetic mechanisms underlying the reversion events have remained unclear, except for the few instances where crossing over or gene conversion have been demonstrated. Here, we report a patient affected with Wiskott--Aldrich syndrome (WAS) caused by a 6-bp insertion (ACGAGG) in the WAS protein gene, which abrogates protein expression. Somatic mosaicism was documented in this patient whose majority of T lymphocytes expressed nearly normal levels of WAS protein. These lymphocytes were found to lack the deleterious mutation and showed a selective growth advantage in vivo. Analysis of the sequence surrounding the mutation site showed that the 6-bp insertion followed a tandem repeat of the same six nucleotides. These findings strongly suggest that DNA polymerase slippage was the cause of the original germ-line insertion mutation in this family and that the same mechanism was responsible for its deletion in one of the propositus T cell progenitors, thus leading to reversion mosaicism.

Distinct interactions of the X-linked lymphoproliferative syndrome gene product SAP with cytoplasmic domains of members of the CD2 receptor family

X-linked lymphoproliferative syndrome (XLP; Duncan's disease) is a primary immunodeficiency disease that manifests as an inability to regulate the immune response to Epstein-Barr virus (EBV) infection. Here we examine the ability of the product of the gene defective in XLP, SAP (DSHP/SH2D1A), to associate with the cytoplasmic domains of several members of the CD2 subfamily of cell surface receptors, including SLAM, 2B4, and CD84. While recruitment of SAP to SLAM occurred in a phosphorylation-independent manner, SAP was found to bind preferentially to tyrosine-phosphorylated cytoplasmic domains within 2B4 and CD84. Missense or nonsense mutations in the SAP open reading frame were identified in five of seven clinically diagnosed XLP patients from different kindreds. Four of these variants retained the ability to bind to the cytoplasmic tails of SLAM and CD84. While ectopic expression of wild-type SAP was observed to block the binding of SHP-2 to SLAM, mutant SAP derivatives that retained the ability to bind SLAM did not inhibit recruitment of SHP-2 to SLAM. In contrast, SAP binding to CD84 had no effect on the ability of CD84 to recruit SHP-2, but instead displaced SHP-1 from the cytoplasmic tail of CD84. These results suggest that mutations in the gene encoding the XLP protein SAP lead to functional defects in the protein that include receptor binding and SHP-1 and SHP-2 displacement and that SAP utilizes different mechanisms to regulate signaling through the CD2 family of receptors.

Bruton's tyrosine kinase is present in normal platelets and its absence identifies patients with X-linked agammaglobulinaemia and carrier females

X-linked agammaglobulinaemia (XLA) is a primary immunodeficiency caused by mutations in the gene coding for Bruton's tyrosine kinase (Btk) and is characterized by an arrest of B-cell development. We analysed Btk protein expression in platelets using flow cytometry and found that normal platelets express large amounts of Btk. Assessment of affected males from 45 unrelated XLA families revealed that platelets of the majority of the patients (37 out of 45 families) had decreased or absent Btk expression, and that platelets from carrier females of these families had both normal and mutated Btk expression, indicating that megakaryocytes in XLA carriers undergo random X-chromosome inactivation. These observations demonstrate that Btk is not crucial for maturation of megakaryocytes and the production of platelets. No correlation between Btk expression in platelets and clinical phenotype was observed in this study. Flow cytometric evaluation using platelets is a simple and rapid method to test Btk expression. It may be used as a screening test for XLA and for carrier detection, followed, if necessary, by more expensive mutation analyses.

Molecular biology of the Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency associated with thrombocytopenia, bloody diarrhea, eczema, recurrent infections, and a high incidence of malignancies. X-linked thrombocytopenia (XLT) is a milder form with predominant platelet abnormalities. Both are caused by mutations of the cytoplasmic WAS protein (WASP). To date, mutations of WASP have been identified in over 340 families and consist of missense and nonsense mutations, deletions and insertions, and splice site mutations. There is a striking correlation between phenotype and genotype. The complex gene product of WASP has multiple functional domains that contribute to actin polymerization, cell motility, intracellular signaling, and apoptosis. Understanding the molecular basis of WAS/XLT not only explains the highly variable clinical phenotype, but also affects the medical management of this serious congenital disorder.

CrkL is an adapter for Wiskott-Aldrich syndrome protein and Syk

Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia are caused by mutations of the WAS protein (WASP) gene. WASP may be involved in the regulation of podosome, an actin-rich dynamic cell adhesion structure formed by various types of cells. The molecular links between WASP and podosomes or other cell adhesion structures are unknown. Platelets express an SH2-SH3 adapter molecule, CrkL, that can directly associate with paxillin, which is localized in podosomes. The hypothesis that CrkL binds to WASP was, therefore, tested. Results from coprecipitation experiments using anti-CrkL and GST-fusion proteins suggest that CrkL binds to WASP through its SH3 domain and that the binding was not affected by WASP tyrosine phosphorylation. The binding of GST-fusion SH3 domain of PSTPIP1 in vitro was also not affected by WASP tyrosine phosphorylation, suggesting that the binding of the SH3 domains to WASP is not inhibited by tyrosine phosphorylation of WASP. Anti-CrkL also coprecipitates a 72-kd protein, which was identified as syk tyrosine kinase, critical for collagen induced-platelet activation. CrkL immunoprecipitates contain kinase-active syk, as evidenced by an in vitro kinase assay. Coprecipitation experiments using GST-fusion CrkL proteins suggest that both SH2 and SH3 domains of CrkL are involved in the binding of CrkL to syk. WASP, CrkL, syk, and paxillin-like Hic-5 incorporated to platelet cytoskeleton after platelet aggregation. Thus, CrkL is a novel molecular adapter for WASP and syk and may potentially transfer these molecules to the cytoskeleton through association with cytoskeletal proteins such as Hic-5.

Unrelated umbilical cord stem cell transplantation for X-linked immunodeficiencies

Banked unrelated umbilical cord blood matched at 5 of 6 human leukocyte antigen loci was used to reconstitute the immune system in 2 brothers with X-linked lymphoproliferative syndrome and 1 boy with X-linked hyperimmunoglobulin-M syndrome. Pretransplant cytoreduction and posttransplant graft-versus-host prophylaxis were given. Hematopoietic engraftment and correction of the genetic defects were documented by molecular techniques. Two years after transplantation, all 3 patients have normal immune systems. These reports support the wider use of banked partially matched cord blood for transplantation in primary immunodeficiencies.

Immunologic reconstitution following bone marrow transplantation for X-linked hyper IgM syndrome

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophage &phi;X174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.

Characterization of soluble CD40 ligand released from human activated platelets

We report here that soluble CD40 ligand (sCD40L) is released from human platelets when activated with collagen or thrombin. The sCD40L was detectable in the culture supernatants of platelets within 30 min after stimulation in vitro, and reached maximal levels in 3 h. The release was blocked by the metalloproteinase inhibitor, KB8301, indicating that the soluble CD40L is made by cleaving the membrane bound CD40L expressed on activated platelets. The sCD40L was undetectable in the supernatant of the activated platelets obtained from patients with X-linked hyper IgM syndrome (XHIM), who have defects in CD40L gene. Since sCD40L has been shown to have biologic function on the activation of vascular endothelial cells and B cells, these findings suggest that platelets play some roles in both inflammation and humoral immune response by releasing soluble CD40L.

Induction, binding specificity and function of human ICOS

Recently, we have identified the inducible co-stimulator (ICOS), an activation-dependent, T cell-specific cell surface molecule related to CD28 and CTLA-4. Detailed analysis of human ICOS presented here shows that it is a 55-60-kDa homodimer with differently N-glycosylated subunits of 27 and 29 kDa. ICOS requires both phorbol 12-myristate 13-acetate and ionomycin for full induction, and is sensitive to Cyclosporin A. ICOS is up-regulated early on all T cells, including the CD28- subset, and continues to be expressed into later phases of T cell activation. On stimulation of T cells by antigen-presenting cells, the CD28/B7, but not the CD40 ligand/CD40 pathway is critically involved in the induction of ICOS. ICOS does not bind to B7-1 or B7-2, and CD28 does not bind to ICOS ligand; thus the CD28 and ICOS pathways do not cross-interact on the cell surface. In vivo, ICOS is expressed in the medulla of the fetal and newborn thymus, in the T cell zones of tonsils and lymph nodes, and in the apical light zones of germinal centers (predominant expression). Functionally, ICOS co-induces a variety of cytokines including IL-4, IL-5, IL-6, IFN-gamma, TNF-alpha, GM-CSF, but not IL-2, and superinduces IL-10. Furthermore, ICOS co-stimulation prevents the apoptosis of pre-activated T cells. The human ICOS gene maps to chromosome 2q33 - 34.

Antibody responses to bacteriophage phi X-174 in human subjects exposed to the antarctic winter-over model of spaceflight

BACKGROUND

It has been proposed that exposure to long-term spaceflight conditions (stress, isolation, sleep disruption, containment, microbial contamination, and solar radiation) or to ground-based models of spaceflight will alter human immune responses, but specific antibody responses have not been fully evaluated.

OBJECTIVE

We sought to determine whether exposure to the 8-month Antarctic winter-over model of spaceflight would alter human antibody responses.

METHODS

During the 1999 Australian National Antarctic Research Expeditions, 11 adult study subjects at Casey, Antarctica, and 7 control subjects at Macquarie Island, sub-Antarctica, received primary and secondary immunizations with the T cell-dependent neoantigen bacteriophage phi X-174. Periodic plasma samples were analyzed for specific antibody function.

RESULTS

All of the subjects from Casey, Antarctica, cleared bacteriophage phi X-174 normally by 1 week after primary immunization, and all had normal primary and secondary antibody responses, including immunologic memory amplification and switch from IgM to IgG antibody production. One subject showed a high normal pattern, and one subject had a low normal pattern. The control subjects from Macquarie Island also had normal immune responses to bacteriophage phi X-174.

CONCLUSIONS

These data do not support the hypothesis that de novo specific antibody responses of subjects become defective during the conditions of the Antarctic winter-over. Because the Antarctic winter-over model of spaceflight lacks the important factors of microgravity and solar radiation, caution must be used in interpreting these data to anticipate normal antibody responses in long-term spaceflight.

The immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX) is caused by mutations of FOXP3

IPEX is a fatal disorder characterized by immune dysregulation, polyendocrinopathy, enteropathy and X-linked inheritance (MIM 304930). We present genetic evidence that different mutations of the human gene FOXP3, the ortholog of the gene mutated in scurfy mice (Foxp3), causes IPEX syndrome. Recent linkage analysis studies mapped the gene mutated in IPEX to an interval of 17-20-cM at Xp11. 23-Xq13.3.

Induction, binding specificity and function of human ICOS

Recently, we have identified the inducible co-stimulator (ICOS), an activation-dependent, T cell-specific cell surface molecule related to CD28 and CTLA-4. Detailed analysis of human ICOS presented here shows that it is a 55-60-kDa homodimer with differently N-glycosylated subunits of 27 and 29 kDa. ICOS requires both phorbol 12-myristate 13-acetate and ionomycin for full induction, and is sensitive to Cyclosporin A. ICOS is up-regulated early on all T cells, including the CD28- subset, and continues to be expressed into later phases of T cell activation. On stimulation of T cells by antigen-presenting cells, the CD28/B7, but not the CD40 ligand/CD40 pathway is critically involved in the induction of ICOS. ICOS does not bind to B7-1 or B7-2, and CD28 does not bind to ICOS ligand; thus the CD28 and ICOS pathways do not cross-interact on the cell surface. In vivo, ICOS is expressed in the medulla of the fetal and newborn thymus, in the T cell zones of tonsils and lymph nodes, and in the apical light zones of germinal centers (predominant expression). Functionally, ICOS co-induces a variety of cytokines including IL-4, IL-5, IL-6, IFN-gamma, TNF-alpha, GM-CSF, but not IL-2, and superinduces IL-10. Furthermore, ICOS co-stimulation prevents the apoptosis of pre-activated T cells. The human ICOS gene maps to chromosome 2q33 - 34.

Wiskott-Aldrich syndrome protein and platelets

Wiskott-Aldrich syndrome (WAS) and X-linked thrombocy topenia (XLT) are caused by mutations of the WAS protein (WASP) gene. The manifestations of the classic WAS phenotype consist of immunodeficiency, eczema and thrombocytopenia. However, thrombocytopenia and small platelets are the only consistent features of WAS and XLT. The exact mechanisms of the development of thrombocytopenia in patients with WAS or XLT are unknown. To date, platelets are the only primary cells in which inducible tyrosine phosphorylation of WASP has been consistently demonstrated. This review focuses on the recent progress in dissecting the causes of thrombocytopenia and the emerging understanding of WASP phosphorylation.

X-linked hyper IgM syndrome: a report of the first case in Thailand with a confirmed mutation of CD40 ligand gene

X-linked hyper IgM (XHIM) syndrome is a rare congenital immunodeficiency disease caused by failure of B cell to isotype switch from IgM to other classes of immunoglobulins in response to infections. Recently, a molecular cloning of the gene responsible for the syndrome, the CD40L gene has been accomplished and the gene was successfully mapped to the long arm of X chromosome at the position Xq26. We, herein, report the first case of molecular proven XHIM in a Thai boy with a classic presentation and with a confirmed mutation of the CD40L gene.

CASE REPORT

A.S. was a 1 year 7 month old boy referred from Buriram Provincial Hospital for a work up and treatment for his recurrent infections consisted of chronic respiratory tract infections with otitis media (since 6 months of age), chronic diarrhea (since 9 months of age) and malnutrition (marasmus) secondary to his longstanding illnesses. He was a product of a consanguineous marriage but without history of similar illness observed in his pedigree. Abnormal laboratory works up included IgG of 300 mg/dl, IgA 10 mg/dl, IgM 1,635 mg/dl, positive stool examinations for Cryptosporidium, chronic colitis on radiographic gastrointestinal follow through study, a positive acid fast bacillus (AFB) stain of gastric aspirate and multiple positive bacterial cultures from various body sources. His anti-HIV serology was negative. His hospital course was significant for several bouts of infections of gastrointestinal, respiratory, and genitourinary systems. His treatment consisted of multiple courses of antibiotics, antituberculous drugs and IVIG administrations. His hospital course was complicated with feeding problem from an esophageal stricture requiring several esophageal dilatations. The analysis of CD40L gene revealed a point mutation of exon 5 (A619T) of the CD40L gene resulting in a stop codon confirming that indeed he had XHIM. He died with Pseudomonas septicemia during the waiting period for a bone marrow transplantation from a cord-blood stem cell.

Evaluation of CD4+ T cell function In vivo in HIV-infected patients as measured by bacteriophage phiX174 immunization

Bacteriophage phiX174 immunization was used to measure CD4(+) T cell function in vivo in human immunodeficiency virus (HIV)-infected patients across all disease stages. Function was evaluated by measuring the ability of T cells to provide help to B cells in antibody production, amplification, and isotype switching. A total of 33 patients and 10 controls received 3 bacteriophage phiX174 immunizations 6 weeks apart. The patients' responses regarding bacteriophage-specific total antibody titers and IgG titers were quantitatively and qualitatively inferior to the controls' responses. Overall, 7 of 33 patients had normal T cell function. Baseline CD4 counts provided the strongest correlation with total antibody and IgG titers. HIV RNA had a weaker association with responses but had some predictive power among patients with a CD4 count >200 cells/microL. Bacteriophage phiX174 immunization seems to be a useful tool for measuring immune function in vivo, which suggests that most HIV-infected patients may have abnormal CD4(+) T cell function despite adequate antiretroviral treatment.

B-cell function in canine X-linked severe combined immunodeficiency

Canine X-linked severe combined immunodeficiency (XSCID) is due to mutations in the common gamma (gammac) subunit of the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors and has a similar clinical phenotype to human XSCID. We have previously shown that the block in T-cell development is more profound in XSCID dogs than in genetically engineered gamma c-deficient mice. In this study we evaluated the B-cell function in XSCID dogs. In contrast to the marked decrease in peripheral B-cells in gamma c-deficient mice, XSCID dogs have increased proportions and numbers of peripheral B-cells as observed in XSCID boys. Canine XSCID B-cells do not proliferate following stimulation with the T-cell-dependent B-cell mitogen, pokeweed mitogen (PWM); however, they proliferate normally in response to the T-cell-independent B-cell mitogen, formalin-fixed, heat-killed Staphylococcus aureus. Canine XSCID B-cells are capable of producing IgM but are incapable of normal class-switching to IgG antibody production as demonstrated by in vitro stimulation with PWM and immunization with the T-cell-dependent antigen, bacteriophage PhiX174. Similar results have been reported for XSCID boys. Thus, it appears that gamma c-dependent cytokines have differing roles in human and canine B-cell development than in the mouse making the XSCID dog a valuable model for studying the role of these cytokines in B-cell development and function.

Mutations of the human BTK gene coding for bruton tyrosine kinase in X-linked agammaglobulinemia

X-linked agammaglobulinemia (XLA) is an immunodeficiency caused by mutations in the gene coding for Bruton agammaglobulinemia tyrosine kinase (BTK). A database (BTKbase) of BTK mutations lists 544 mutation entries from 471 unrelated families showing 341 unique molecular events. In addition to mutations, a number of variants or polymorphisms have been found. Mutations in all the five domains of BTK cause the disease, the single most common event being missense mutations. Most mutations lead to truncation of the enzyme. The mutations appear almost uniformly throughout the molecule. About one-third of point mutations affect CpG sites, which usually code for arginine residues. The putative structural implications of all the missense mutations are provided in the database. BTKbase is available at http://www.uta.fi/imt/bioinfo.

Mapping of a syndrome of X-linked thrombocytopenia with Thalassemia to band Xp11-12: further evidence of genetic heterogeneity of X-linked thrombocytopenia

X-linked thrombocytopenia with thalassemia (XLTT; Online Mendelian Inheritance in Man [OMIM] accession number 314050) is a rare disorder characterized by thrombocytopenia, platelet dysfunction, splenomegaly, reticulocytosis, and unbalanced hemoglobin chain synthesis. In a 4-generation family, the gene responsible for XLTT was mapped to the X chromosome, short arm, bands 11-12 (band Xp11-12). The maximum lod score possible in this family, 2.39, was obtained for markers DXS8054 and DXS1003, at a recombination fraction of 0. Recombination events observed for XLTT and markers DXS8080 and DXS8023 or DXS991 define a critical region that is less than or equal to 7.65 KcM and contains the gene responsible for the Wiskott-Aldrich syndrome (WAS; OMIM accession number 301000) and its allelic variant X-linked thrombocytopenia (XLT; OMIM accession number 313900). Manifestations of WAS include thrombocytopenia, eczema, and immunodeficiency. In WAS/XLT the platelets are usually small, and bleeding is proportional to the degree of thrombocytopenia. In contrast, in XLTT the platelet morphology is normal, and the bleeding time is disproportionately prolonged. In this study no alteration in the WAS gene was detected by Northern blot or Western blot analysis, flow cytometry, or complimentary DNA dideoxynucleotide fingerprinting or sequencing. As has been reported for WAS and some cases of XLT, almost total inactivation of the XLTT gene-bearing X chromosome was observed in granulocytes and peripheral blood mononuclear cells from 1 asymptomatic obligate carrier. The XLTT carrier previously found to have an elevated alpha:beta hemoglobin chain ratio had a skewed, but not clonal, X-inactivation pattern favoring activity of the abnormal allele. Clinical differences and results of the mutation analyses make it very unlikely that XLTT is another allelic variant of WAS/XLT and strongly suggest that X-linked thrombocytopenia mapping to band Xp11-12 is a genetically heterogeneous disorder.

Progressive specific immune attrition after primary, secondary and tertiary immunizations with bacteriophage phi X174 in asymptomatic HIV-1 infected patients

BACKGROUND

Antibody responses to immunization are often compromised in patients infected by HIV-1, and the use of childhood immunization in affected children is controversial. We investigated whether multiple immunizations with a T cell-dependent neoantigen, bacteriophage phiX174, induce selective immune attrition and post-vaccination viremia.

METHODS

Seventeen asymptomatic, antiretroviral therapy-naïve HIV-1-infected patients with a CD4 cell count of 450 cells/microl or greater were immunized in 1990/1991 with three intravenous doses of bacteriophage phiX174. Group 1 received zidovudine (ZDV) during the primary and secondary immunization. Group 2 received ZDV exclusively during the tertiary immunization. Bacteriophage-specific antibodies of the IgM and IgG class, lymphocyte phenotypes (CD4+, CD8+, CD4+DR+, CD8+DR+, CD4+CD45RO+ and CD4+45RA+, CD4+CD45RO+DR+) and HIV-1 plasma viremia were measured sequentially.

RESULTS

In both patient groups the primary, secondary and tertiary antibody responses, as expressed by geometric mean antibody titres and IgM to IgG switch, were impaired. Booster immunizations resulted in a progressive attrition of specific antibody responses to bacteriophage. Antibodies to tetanus toxoid remained stable. The HIV-1 viral loads, which were evaluated in archived specimens from eight patients, increased after immunization but returned to baseline approximately 4 weeks later. The humoral immune attrition and increases in plasma viremia were blunted by concomitant short courses of ZDV.

DISCUSSION

Multiple boosters of immunizations in asymptomatic treatment-naive HIV-1-infected patients may result in a specific immune attrition and vaccine-induced viremia. Short-term monotherapy with ZDV may have blunted these adverse effects. Hyperimmunization of HIV-1-infected patients may be detrimental unless accompanied by antiretroviral therapy.

Rapid tyrosine phosphorylation and activation of Bruton's tyrosine/Tec kinases in platelets induced by collagen binding or CD32 cross-linking

Stimulation of the platelet nonintegrin collagen receptor, glycoprotein VI, evokes a signaling response similar to that induced by antigen receptor activation in B and T lymphocytes. A key transducer of the lymphocyte signaling pathways is the Bruton's tyrosine kinase (Btk)/Tec kinase family, which connects receptors to the elevation of intracellular-free calcium levels. An important signaling function for Btk in collagen-induced platelet activation in vitro was recently demonstrated by other researchers using Btk-deficient platelets from patients with X-linked agammaglobulinemia (XLA). Since Btk-deficiency does not induce an overt platelet-based bleeding disorder in vivo, collagen receptor responses may include other Btk/Tec kinase family members in normal platelets. Both Btk and Tec had increased tyrosine following stimulation of collagen receptors or CD32 cross-linking. Data from kinetic analyses and inhibitor studies and the use of phosphopeptide-specific antibodies recognizing 2 Btk regulatory phosphorylated tyrosine residues suggest a mechanism for coordinate recruitment of Btk and Tec through the immunoreceptor tyrosine-based activation motif, Src family kinases, and phosphatidylinositol 3-kinase. In XLA platelets, collagen treatment increased tyrosine phosphorylation of Tec and several other signaling proteins, including Lyn, Fyb, Slp-76, and the Wiskott-Aldrich syndrome protein. This indicates that important elements of the collagen signaling pathway proximal and distal to Btk and Tec are preserved despite the lack of functional Btk. The results are consistent with the conclusion that activation of Tec may sustain XLA platelet function in vivo, while some in vitro assays of nonintegrin collagen receptor signaling through the Btk/Tec kinase family reflect the additive dosage of the transducers. (Blood. 2000;95:1663-1670)

Effects of administration of a single dose of a humanized monoclonal antibody to CD11a on the immunobiology and clinical activity of psoriasis

BACKGROUND

CD11a/CD18 comprise subunits of leukocyte function associated antigen (LFA-1), a T-cell surface molecule important in T-cell activation, T-cell emigration into skin, and cytotoxic T-cell function.

OBJECTIVE

We explored the immunobiologic and clinical effects of treating moderate to severe psoriasis vulgaris with a single dose of humanized monoclonal antibody against CD11a (hu1124).

METHODS

This was an open label study with a single dose of hu1124 at doses of 0.03 to 10 mg/kg. Clinical (Psoriasis Area and Severity Index [PASI]) and immunohistologic parameters (epidermal thickness, epidermal and dermal T-cell numbers, and keratinocyte intercellular adhesion molecule 1 [ICAM-1] expression) were followed.

RESULTS

Treatment with hu1124, at doses higher than 1.0 mg/kg (group III), completely blocks CD11a staining for at least 14 days in both blood and psoriatic plaques. At 0.3 to 1.0 mg/kg, T-cell CD11a staining was completely blocked; however, blockade lasted less than 2 weeks (group II). Only partial saturation of either blood or plaque cellular CD11a was observed at doses of hu1124 between 0.01 and 0.1 mg/kg (group I). This pharmacodynamic response was accompanied by decreased numbers of epidermal and dermal CD3(+) T cells, decreased keratinocyte and blood vessel expression of ICAM-1, and epidermal thinning. Statistically significant drops in PASI compared with baseline were observed in group II patients at weeks 3 and 4 and in group III patients at weeks 2 through 10. No significant drop in PASI score was observed in group 1. Adverse events were mild at doses of 0.3 mg/kg or less and included mild chills, abdominal discomfort, headache, and fever. At a single dose of 0.6 mg/kg or higher, headache was the most common dose-limiting toxicity observed.

CONCLUSION

Targeting CD11a may improve psoriasis by inhibiting T-cell activation, T-cell emigration into the skin, and cytotoxic T-cell function.

Actin cytoskeletal function is spared, but apoptosis is increased, in WAS patient hematopoietic cells

Mutations in the Wiskott-Aldrich syndrome protein (WASP) have been hypothesized to cause defective actin cytoskeletal function. This resultant dysfunction of the actin cytoskeleton has been implicated in the pathogenesis of Wiskott-Aldrich syndrome (WAS). In contrast, it was found that stimulated actin polymerization is kinetically normal in the hematopoietic lineages affected in WAS. It was also found that the actin cytoskeleton in WAS platelets is capable of producing the hallmark cytoarchitectural features associated with activation. Further analysis revealed accelerated cell death in WAS lymphocytes as evidenced by increased caspase-3 activity. This increased activity resulted in accelerated apoptosis of these cells. CD95 expression was also increased in these cells, suggesting an up-regulation in the FAS pathway in WAS lymphocytes. Additionally, inhibition of actin polymerization in lymphocytes using cytochalasin B did not accelerate apoptosis in these cells. This suggests that the accelerated apoptosis observed in WAS lymphocytes was not secondary to an underlying defect in actin polymerization caused by mutation of the WAS gene. These data indicate that WASP does not play a universal role in signaling actin polymerization, but does play a role in delaying cell death. Therefore, the principal consequence of mutations in the WAS gene is to accelerate lymphocyte apoptosis, potentially through up-regulation of the FAS-mediated cell death pathway. This accelerated apoptosis may ultimately give rise to the clinical manifestations observed in WAS. (Blood. 2000;95:1283-1292)

Lentiviral and murine retroviral transduction of T cells for expression of human CD40 ligand

Efficient transduction of primary human T cells is an important goal toward treating a number of genetic defects. Patient T cells could be harvested by leukapheresis, transduced, and returned to the donor. A wide range of secreted or cell surface therapeutic proteins may be delivered in this way. The ability to produce antibodies is the consequence of interactions between T cells and B cells and lack of expression of CD40 ligand (CD40L) on T cells causes X-linked hyper-IgM syndrome (XHIM). We are investigating delivery of a normal CD40 ligand to treat this disorder. We tested promoters driving the expression of either reporter genes such as enhanced green fluorescent protein (eGFP) or human CDC40L. Using murine retroviruses, the best able to drive gene expression in T cells was the cytomegalovirus (CMV) promoter enhancer element; however, transduction efficiency was low. To achieve efficient, high-level gene expression we tested lentiviral gene delivery vectors. At a low multiplicity of infection (MOI) (0.5-2) a large fraction of target cells was transduced by lentiviral vectors (40-93%), and the strength of gene expression was high, as determined by flow cytometric analysis. We monitored the expression of eGFP or human CD40L on T cell lines and untransformed primary human T cells from normal and CD40L-deficient patients. We achieved efficient gene expression without an extended exposure to virus, and without the need for selection. These results are encouraging for efficient lentivirus-mediated transduction of refractory human cells to achieve therapeutic gene delivery.

Mutations of the WASP gene in 10 Japanese patients with Wiskott-Aldrich syndrome and X-linked thrombocytopenia

Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, immunodeficiency, and eczema. X-linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott-Aldrich syndrome protein (WASP) gene. In this study, we identified mutations of the WASP gene in 10 Japanese patients from 9 unrelated families with WAS/XLT. All XLT patients (n = 3) and one WAS patient had a missense mutation at the PH domain of WASP. Two WAS patients had nonsense mutations. One WAS patient had exon 8 skipping caused by one nucleotide deletion at the acceptor site of intron 7. Three WAS patients had genomic deletions; one of the three had a large genomic deletion involving exons 3 to 7. Codons 45 and 86 seem to be the hot spots of the WASP mutation, because missense mutations in these codons have been reported previously in several WAS/XLT patients in addition to the patients in this report, and patients with the same mutation show a similar clinical phenotype. All other mutations are novel, indicating that the mutations of WASP are heterogeneous. EB virus-transformed cell lines from XLT patients expressed nearly normal amounts of WASP, whereas those from typical WAS patients expressed almost undetectable amounts of WASP. We conclude that the analysis of gene mutation and protein expression of WASP are useful together in assessing the severity of WAS.

Physical and functional association of LFA-1 with DNAM-1 adhesion molecule

Whereas ligation of the DNAM-1 adhesion molecule triggers cytotoxicity mediated by normal NK and T cells, this function was defective in NK cell clones from leukocyte adhesion deficiency syndrome. However, genetic reconstitution of cell surface expression of LFA-1 restored the ability of DNAM-1 to initiate anti-DNAM-1 mAb-induced cytotoxicity, indicating a functional relationship between DNAM-1 and LFA-1. Further studies demonstrated that LFA-1 physically associates with DNAM-1 in NK cells and anti-CD3 mAb stimulated T cells, for which serine phosphorylation of DNAM-1 plays a critical role. In addition, cross-linking of LFA-1 induces tyrosine phosphorylation of DNAM-1, for which the Fyn protein tyrosine kinase is responsible. These results indicate that DNAM-1 is involved in the LFA-1-mediated intracellular signals.

WASP is involved in proliferation and differentiation of human haemopoietic progenitors in vitro

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive disorder characterized by thrombocytopenia, immunodeficiency and eczema. X-linked thrombocytopenia (XLT) is a mild form of WAS with isolated thrombocytopenia. Both phenotypes are caused by mutation of the Wiskott-Aldrich syndrome protein (WASP) gene. In this study we investigated the role of WASP in the differentiation of CD34-positive (CD34+) cells isolated from the bone marrow of patients with WAS (n = 5) or with XLT (n = 4). Megakaryocyte colony formation was significantly decreased in patients with WAS when compared with normal controls. The formation of granulocyte-macrophage colonies and erythroid bursts were also decreased in WAS patinets. In contrast, in XLT patients, formation of all these colonies was normal. However, in vitro proplatelet formation of megakaryocytes induced by thrombopoietin was markedly decreased in both XLT and WAS. Electron microscopic examination revealed that megakaryocytes obtained from WAS or XLT patients grown in vitro had abnormal morphologic features, which seemed to be caused by defective actin cytoskeletal organization, including labyrinth-like structures of the demarcation membrane system and deviated distribution of the alpha-granules and demarcation membrane system. These observations indicate that WASP is involved in the proliferation and differentiation of CD34+ haemopoietic progenitor cells probably by its participation in signal transduction and in the regulation of the cytoskeleton.

Genetic linkage of hyper-IgE syndrome to chromosome 4

The hyper-IgE syndrome (HIES) is a rare primary immunodeficiency characterized by recurrent skin abscesses, pneumonia, and highly elevated levels of serum IgE. HIES is now recognized as a multisystem disorder, with nonimmunologic abnormalities of the dentition, bones, and connective tissue. HIES can be transmitted as an autosomal dominant trait with variable expressivity. Nineteen kindreds with multiple cases of HIES were scored for clinical and laboratory findings and were genotyped with polymorphic markers in a candidate region on human chromosome 4. Linkage analysis showed a maximum two-point LOD score of 3.61 at recombination fraction of 0 with marker D4S428. Multipoint analysis and simulation testing confirmed that the proximal 4q region contains a disease locus for HIES.

Long-term interferon alpha maintenance therapy for chronic hepatitis C infection in a patient with common variable immune deficiency

A 46-year-old woman with common variable immune deficiency acquired acute non-A, non-B hepatitis from contaminated intravenous gamma globulin in 1983. For 6 years she had fluctuating elevations of her serum aminotransferase levels. In 1990 her serum was documented to be hepatitis C virusribonucleic acid positive by polymerase chain reaction, and her liver biopsy revealed chronic hepatitis with early cirrhosis (Knodell score, 15 points). Hepatitis C virus genotyping indicated that she had been infected with the type 3 genotype. She subsequently underwent treatment with interferon alpha (IFN-alpha) for 1 year and experienced biochemical, virologic, and histologic (Knodell score, 9) suppression. She was continued on maintenance therapy for an additional 7 years, with sustained biochemical and virologic suppression. During the sixth year of therapy, complications of portal hypertension were noted with mild ascites and eventually bleeding esophageal varices. This case report documents a favorable biochemical, virologic, and histologic response to IFN-alpha therapy in this setting; supports the notion that the natural progression of hepatitis C virus infection may be more aggressive in patients with common variable immune deficiency; and, although complications of portal hypertension eventually occurred, the suppressive maintenance IFN therapy may have delayed their onset. The future establishment of the long-term effects of IFN therapy on important clinical outcomes is necessary to understand better its therapeutic benefit in chronic hepatitis C infection.