Ersoy F

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.

Mutations in RAB27A cause Griscelli syndrome associated with haemophagocytic syndrome.

Griscelli syndrome (GS, MIM 214450), a rare, autosomal recessive disorder, results in pigmentary dilution of the skin and the hair, the presence of large clumps of pigment in hair shafts and an accumulation of melanosomes in melanocytes. Most patients also develop an uncontrolled T-lymphocyte and macrophage activation syndrome (known as haemophagocytic syndrome, HS), leading to death in the absence of bone-marrow transplantation. In contrast, early in life some GS patients show a severe neurological impairment without apparent immune abnormalities. We previously mapped the GS locus to chromosome 15q21 and found a mutation in a gene (MYO5A) encoding a molecular motor in two patients. Further linkage analysis suggested a second gene associated with GS was in the same chromosomal region. Homozygosity mapping in additional families narrowed the candidate region to a 3.1-cM interval between D15S1003 and D15S962. We detected mutations in RAB27A, which lies within this interval, in 16 patients with GS. Unlike MYO5A, the GTP-binding protein RAB27A appears to be involved in the control of the immune system, as all patients with RAB27A mutations, but none with the MYO5A mutation, developed HS. In addition, RAB27A-deficient T cells exhibited reduced cytotoxicity and cytolytic granule exocytosis, whereas MYO5A-defective T cells did not. RAB27A appears to be a key effector of cytotoxic granule exocytosis, a pathway essential for immune homeostasis.

Griscelli Disease: Genotype–Phenotype Correlation in an Array of Clinical Heterogeneity

Griscelli disease is a rare autosomal recessive disorder characterized by diffuse pigmentary dilution and occurrence of acute phases of uncontrolled lymphocyte and macrophage activation, so-called “hemophagocytic syndrome” (HS) that leads to death. Recently, two closely linked genes located on human 15q21 region have been found to be responsible for the disease. We present clinical and laboratory findings of 13 unrelated patients with Griscelli disease as well as mutation analyses in an effort to define a genotype–phenotype correlation. Eight patients who showed RAB27A mutations presented with HS. In contrast, two patients who primarily presented with a neurological impairment in the absence of infection susceptibility or HS were found to have homozygous MYO5A mutations. No mutation in RAB27A could be detected in the other three patients. One of the latter developed HS at a rather late age, while the other two are free of HS at 12 and 15 years of age. Griscelli disease presents with a heterogeneous clinical picture that seems to reflect the involved gene defect. This genotype–phenotype correlation suggests that the natural course of the disease and outcome is dictated by the site and type of the genetic mutation.

Altered apoptotic profiles in irradiated patients with increased toxicity

PURPOSE A retrospective study of radiation-induced apoptosis in CD4 and CD8 T-lymphocytes, from 12 cancer patients who displayed enhanced toxicity to radiation therapy and 9 ataxia telangiectasia patients, was performed to test for altered response compared to healthy blood-donors and normal cancer patients. METHODS AND MATERIALS Three milliliters of heparinized blood from each donor was sent via express post to the Paul Scherrer Institute (PSI) for subsequent examination. The blood was diluted 1:10 in RPMI medium, irradiated with 0-, 2-, or 9-Gy X-rays, and incubated for 48 h. CD4 and CD8 T-lymphocytes were then labeled using FITC-conjugated antibodies, erythrocytes were lysed, and the DNA stained with propidium iodide. Subsequently, cells were analyzed using a Becton Dickinson FACScan flow cytometer. Radiation-induced apoptosis was recognized in leukocytes as reduced DNA content attributed to apoptosis-associated changes in chromatin structure. Apoptosis was confirmed by light microscopy, electron microscopy, and by the use of commercially available apoptosis detection kits (in situ nick translation and Annexin V). Data from hypersensitive individuals were compared to a standard database of 105 healthy blood-donors, and a database of 48 cancer patient blood donors who displayed normal toxicity to radiation therapy. To integrate radiosensitivity results from CD4 and CD8 T-lymphocytes after 2 and 9 Gy, z-score analyses were performed. RESULTS A cohort of 12 hypersensitive patients was evaluated; 8 showed enhanced early toxicity, 3 showed enhanced late toxicity, and 1 showed both. The cohort displayed less radiation-induced apoptosis (-1.8 sigma) than average age-matched donors. A cohort of 9 ataxia telangiectasia homozygotes displayed even less apoptosis (-3.6 sigma). CONCLUSION The leukocyte apoptosis assay appears to be a useful predictor of individuals likely to display increased toxicity to radiation therapy; however, validation of this requires a prospective study.

Impaired IgG Antibody Production to Pneumococcal Polysaccharides in Patients with Ataxia–Telangiectasia

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

Presentation of Interleukin-12/-23 Receptor β1 Deficiency with Various Clinical Symptoms of Salmonella Infections

Clinical disease caused by weakly pathogenic mycobacterial species, Mycobacterium bovis Bacille Calmette-Guérin (BCG) and non-tuberculous environmental mycobacteria (EM), which is known as Mendelian susceptibility to mycobacterial disease (MSMD), is a rare entity defined recently. Infections with the more virulent Mycobacterium species, M. tuberculosis, may have largely gone unnoticed in these patients due to early death. Mutations in five proteins (IFNγR1, IFNγR2, IL-12/IL-23Rβ1, IL-12/IL-23p40 and STAT1) have been found in MSMD. These patients are prone to surprisingly few other infectious diseases mainly to salmonellosis. Here we present three IL-12/IL-23Rβ1 deficient patients from three different families and with different genetic mutations, who presented exclusively with Salmonella infections. Bacteremia and lymph node involvement were common clinical expressions. Leukocytoclastic vasculitis developed in one of these patients. Two patients were not inoculated with BCG, the third patient did not develop BCG infection although BCG vaccine had been given twice at ages of 1 and 7 years. All three patients responded well to antibiotic treatment. In conclusion, patients with chronic, recurrent or complicated Salmonella infections should be screened for MSMD, particularly for IL-12/IL-23p40/IL-12R/-23Rβ1 deficiency. Conversely, in patients with genetic IL-12/-23Rβ1 deficiency a full evaluation for Salmonella infection is required. IL-12/IL-23p40/IL-12R/IL-23Rβ1 deficiency seem to be underdiagnosed in patients with salmonellosis, and since such patients need prolonged therapy, diagnosis is important.

Development of systemic lupus erythematosus in a patient with selective complete C1q deficiency

Abstract A 7-year-old male with recurrent erythematous and desquamated skin lesions and respiratory infections was diagnosed as selective complete C1q deficiency following detailed studies of the complement system. His asymptomatic sister also had selective complete C1q deficiency. During a follow up period of 3 years, his skin lesions persisted, he suffered from recurrent bronchopneumonias and glomerulonephritis developed. Renal function deteriorated with the appearance of anti-DNA antibodies. Renal biopsy was consistent with systemic lupus erythematosus. The patient was treated with immunosuppressive drugs, but died of renal failure. It is postulated that in this patient defective clearance of antigen-antibody complexes by the reticulo- endothelial system resulted in progressive renal disease as observed in other complement deficiencies. A retrospective molecular study disclosed a point mutation in the ClqA chain gene in a heterozygous state in parents and two siblings; in a homozygous state in the asymptomatic sister. The reason why some individuals with this defect are asymptomatic is not known at present. Diagnosis of heterozygotes by molecular studies is extremely important to give genetic counselling to the family. Conclusion Patients with recurrent infections, ery-thematous desquamative skin lesions, malar rash and oral mucosal involvement should be screened for complement Clq deficiency.

Antibody Response to a Seven-Valent Pneumococcal Conjugated Vaccine in Patients with Ataxia-Telangiectasia

Immunodeficiency is a characteristic feature of ataxia-telangiectasia (A-T). Humoral immunodeficiency generally consists of hypogammaglobulinemia and impaired antibody response to bacterial and viral antigens. We previously observed defective antibody response to 23-valent pneumococcal polysaccharide vaccine (PPV) in 96% of 29 patients with A-T. In this study, we investigated the antibody response to a seven-valent pneumococcal conjugate vaccine, PCV7, in 14 patients with A-T. IgG antibody levels to four pneumococcal serotypes, 6B, 14, 19F, 23F, which were included in PCV7, were measured by ELISA in pre- and postimmunization serum samples. Antibody titers against each individual Streptococcus pneumoniae serotype was considered to be positive when serotype specific pneumococcal antibody titer was higher than 10% (>10 U/mL) of the reference plasma pool level. However, when the fold increase (FI) in postimmunization antibody titer was less than two, the subject was determined to be unresponsive to the given serotype. The values were compared with the results obtained in age- and ethnic-matched children after one dose of PPV. Only two patients produced antibodies to one serotype each; one to serotype 19 with a fold increase of <2, and the other to serotype 23F with a fold increase of 5.7 based on the above criteria, although the differences between pre- and postvaccine antibody titers for serotypes 14, 19, and 23 appeared to be statistically significant. In conclusion, A-T patients failed to respond to one dose of PCV7 vaccine. Two or more doses of conjugated vaccine may be required to recruit the help of T lymphocytes in A-T patients.

Association of tumour necrosis factor-alpha -308 G/A polymorphism with primary open-angle glaucoma

Background:  Tumour necrosis factor‐alpha (TNF‐α) is an important proinflammatory cytokine driving axonal degeneration and retinal ganglion cell apoptosis in glaucoma. The aim of the study was to evaluate the association of TNF‐α ‐308 G/A and ‐238 G/A polymorphisms with primary open‐angle glaucoma (POAG).

Isolated cutaneous response to granulocyte-monocyte colony stimulating factor in fatal idiopathic disseminated Bacillus-Calmette-Guerin infection.

Abstract Severe disseminated Bacillus-Calmette-Guerin (BCG) infection is very rare and has been regarded as idiopathic when no immunodeficiency is present. This entity seems to be due to several new types of inherited abnormalities in the pathways important in defence against Mycobacteria. Although improvement with interferon-γ (IFN-γ) has been reported in some patients, to our knowledge there are no reports on the effect of other cytokines in the treatment of these patients. We report here the clinical response to IFN-γ and granulocyte-monocyte colony stimulating factor (GM-CSF) treatment in a patient with idiopathic disseminated BCG infection who failed to respond to multiple antimycobacterial agents. The patient showed partial and transitory response to IFN-γ, however, GM-CSF treatment led to rapid improvement of skin lesions within 2 weeks without any effect on the progression of the disease in the other organ systems. Conclusion The response of idiopathic disseminated Bacillus-Calmette-Guerin infection to granulocyte-monocyte colony stimulating factor treatment was limited to cutaneous lesions. Granulocyte-monocyte colony stimulating factor may have acted to promote wound healing or the levels of this factor achieved in other affected organs may have been inadequate.