Akihito Ishizaka

The inductive effect of interleukin-4 on IgG4 and IgE synthesis in human peripheral blood lymphocytes

Using murine monoclonal antibodies against human IgG subclasses, specific and sensitive ELISAs assay to quantify the four human IgG subclasses in cell culture supernaUints were established. The effect of human recombinant interleukin‐4 (IL‐4) on the regulation of IgG subclasses by normal peripheral blood lymphocytes was investigated. In addition to the enhancement of lgE synthesis. IL‐4 preferentially induced IgG4 synthesis in vitro, whereas IL‐4 had no effect on IgGl, IgG2, and IgG3 synthesis. IL‐4‐induced IgG4 production was blocked in a dose‐dependent manner by recombinant interferon‐gamma and anti‐human IL‐4 monoclonal antibody. Collectively, this data indicates that IL‐4 plays an important regulatory role in both IgG subclass and IgE synthesis.

A Japanese family of X-linked auto-immune enteropathy with haemolytic anaemia and polyendocrinopathy

Three cases of X-linked auto-immune enteropathy with haemolytic anaemia and polyendocrinopathy are described from one related Japanese kindred. Two boys had died due to severe diarrhoea accompanied by total or subtotal intestinal villous atrophy.In contrast, although one patient showed the same symptoms and had circulating IgG antibodies against enterocytes, his condition improved dramatically and he developed well following the use of cyclosporin A (CSA). CSA may be beneficial in patients with this rare disorder. Auto-immune enteropathy should be considered as a cause of protracted diarrhoea with unknown aetiology.

Development of hypogammaglobulinaemia in a patient with common variable immunodeficiency

A 3-year-old boy who developed common variable immunodeficiency was investigated for the development of hypogammaglobulinaemia. During a period of 4 years, the combined deficiency of IgA, IgG2 and IgG4 proceeded to include IgG1 and finally IgG3 and IgM. This order of isotypes of IgG subclass deficiencies corresponded to the gene order for the heavy chain constant region for immunoglobulins on chromosome 14.

Distinct clonotypic Epstein-Barr virus-induced fatal lymphoproliferative disorder in a patient with Wiskott-Aldrich syndrome.

Background. Recently, reports of Epstein–Barr virus (EBV)‐induced lymphoproliferative disorders (LPD) have increased in number among immunosuppressed recipients of organ transplants. The importance of analyzing both the immunoglobulin gene and EBV termini is advocated for the investigation of pathogenetic mechanisms for clonal proliferation in EBV‐induced LPD; however, the oncogenic mechanisms of EBV‐induced LPD remain unclear. Furthermore, there are very few clonotypic studies of EBV‐induced LPD in patients with primary immunodeficiency diseases. The authors studied the clonality of an EBV‐induced fatal LPD in a 20‐year‐old patient with Wiskott‐Aldrich syndrome (WAS), an X‐linked recessive primary immunodeficiency disease.

Successful intravenous immunoglobulin therapy for recurrent pneumococcal otitis media in young children.

Serum immunoglobulin levels and naturally occurring antibody titres againstStreptococcus pneumoniae were measured in seven children aged 1–1.9 years with recurent pneumococcal acute otitis media (AOM). Three of them had low IgG2 levels. Mean antibody levels of anti-pneumococcal IgG1 and anti-pneumococcal IgG2 were significantly lower in patients when compared to those of healthy controls and children who had less frequent episodes of AOM. Following treatment with intravenous immunoglobulin (IVIG) for 6 months, anti-pneumococcal IgG1 and IgG2 antibody levels increased and the number of episodes of AOM decreased in all patients. Following the discontinuation of IVIG therapy, no AOM episode occurred. Serum levels of anti-pneumococcal IgG1 and IgG2 were normal, which were measured in three subjects at 5,6, and 12 months after the cessation of IVIG therapy. These results suggested that delayed maturation of anti-pneumococcal antibody production caused recurrent AOM and this condition was corrected by IVIG therapy.

Comparison of a Lateral-Flow Immunochromatography Assay with Real-Time Reverse Transcription-PCR for Detection of Human Metapneumovirus

ABSTRACT A lateral-flow immunochromatography (IC) assay for the detection of human metapneumovirus (hMPV) has been developed by using two mouse monoclonal antibodies to the nucleocapsid protein of hMPV. The purpose of this study was to compare the virus detection rate in nasopharyngeal secretions by the IC assay with that by real-time reverse transcription-PCR (RT-PCR). We collected nasopharyngeal swab samples from 247 children with respiratory symptoms in Sapporo, Japan, during the period from April to July 2007. Sixty-eight of the 247 children were positive for hMPV by real-time RT-PCR. When the real-time RT-PCR was used as the reference standard, the IC assay results were positive for 48 of the 68 real-time RT-PCR-positive children (70.6% sensitivity) and 8 of the 179 real-time RT-PCR-negative children (95.5% specificity). Although the sensitivity of the IC assay is lower than that of real-time RT-PCR, the IC assay is a rapid and useful test for the diagnosis of hMPV infections in children.

Phenytoin-induced IgG2 and IgG4 deficiencies in a patient with epilepsy.

A five‐year‐old girl with epilepsy and recurrent respiratory infections was investigated for serum IgG subclass concentrations. She was diagnosed as having a combined deficiency of IgG2 and IgG4 with a decreased serum concentration of IgA and IgG3 and was given replacement therapy with iv immunoglobulins. Since then, she has been free from respiratory infections. After phenytoin therapy was stopped, IgG subclass deficiency improved. This case describes the further action of phenytoin on the immune system, adding IgG subclass deficiency to the list.

Interleukin‐4 regulates the interleukin‐2 receptors on human peripheral blood B lymphocytes

The high‐affinity interleukin‐2 (IL‐2) receptor (IL‐2R) consists of the non‐covalent association of at least two subunits, p55 and p70–75, capable of binding IL‐2 with low and intermediate affinity, respectively. We studied the effects of cytokines on the IL‐2R expressed on human peripheral blood B lymphocytes using monoclonal antibodies specific for IL‐2R p55 and IL‐2R p70–75, by means of two‐colour flow cytometric analysis. In freshly isolated peripheral blood B lymphocytes, the p55 subunit was expressed only in a small population (7.0% of CD20+ cells), whereas the p70–75 subunit was expressed in a large population (89.0% of CD20+ cells). Of the cytokines studied, interleukin‐4 (IL‐4) and interferon‐gamma (IFN‐γ) were involved in the regulation of IL‐2R on B cells. After a 2‐day incubation with IL‐4, expression of IL‐2R p55 was markedly induced, but expression of IL2‐R p70 –75 was profoundly suppressed in a dose‐dependent manner. These abilities of IL‐4 to promote IL‐2R p55 expression and suppress IL‐2R p70–75 expression were inhibited by the presence of I FN‐γ. Other cytokines, including IL‐1, IL‐2, IL‐5, and IL‐6, had little effect on the expression of these two subunits. These findings suggest that IL‐4 is a cytokine modulating B cell response through the regulation of IL‐2R.

Evaluation of the proliferative response of lymphocytes by measurement of intracellular ATP

The measurement of intracellular ATP levels by luciferin-luciferase-induced bioluminescence was used for the evaluation of proliferative responses of human mononuclear cells to lectins. A linear relationship was observed between the number of cells and the amount of ATP in the samples, and high reproducibility was obtained. The ATP content of samples containing lectin-stimulated mononuclear cells increased with time, and a significant difference from unstimulated cells was obtained 48 h after initiation of the culture. Furthermore pretreatment with mitomycin C strikingly increased the ATP level of lectin-stimulated cells, but not that of unstimulated cells was obtained. These findings suggest that the proliferative response of mononuclear cells can be measured simply without the use of isotopes, and that earlier events occurring in stimulated cells may be analyzed by this simple method.

Hyper-response of serum IgG1 to Staphylococcus aureus peptidoglycan in patients with hyper-IgE syndrome

The hyper‐IgE (HIE) syndrome is characterized by high IgE scrum levels, chronic dermatitis and recurrent infections. To determine whether an impairment of the antibody response to Staphylococcus aureus contributes to infections in this syndrome we measured total serum IgG subclass, specific IgG1 and IgG2 levels against peptidoglycan (PG). the immunodominant cell wall component of S. aureus and serum opsonic activity lo PG. Of the 14 patients with HIE syndrome, nine had increased level of serum IgG1 and six had IgG2 subclass deficiency. In regard to specific response of IgG1 and IgG2 antibodies to PG. patients were divided into live groups related to ages and compared with 10 control subjects for each age cohort. Patients with HIE syndrome had significant high levels of serum‐specific IgG1 to PG and significant decreased levels of serum‐specific lgG2 lo PG in all five groups. Additionally, serum opsonic activity in patients was significantly higher than that in normal control subjects. It is concluded that IgG2 deficiency or poor IgG2 antibody response to S. aureus is not the explanation of (he abnormal susceptibility to S. aureus infections of HIE patients.