Hideaki Tashita

Reduced Expression of the Interferon‐Gamma Messenger RNA in IgG2 Deficiency

The specific defect that causes IgG2 deficiency, which is one of the primary immunodeficiencies, is unknown. Recently, it was shown that interferon‐γ (IFN‐γ) induces synthesis of human germline Cγ2 transcripts. In the authors’ previous study and the present one, peripheral blood lymphocytes (PBLs) of all five tested patients with IgG2 deficiency failed to produce enough IFN‐γ when stimulated with phytohaemagglutinin or concanavalin A although they produced a sufficient amount of interleukin‐2 (IL‐2). The low level of IgG2 production in pokeweed mitogen‐stimulated PBLs of four tested patients was improved by the addition of recombinant IFN‐γ. In this study, the amount of IFN‐γ messenger RNA showed various degrees of reduction in all five tested patients. Sequence analysis of the IFN‐γ coding regions and flanking regions revealed neither a point mutation nor a deletion for any of the patients. Thus the results suggest that the reduced expression of IFN‐γ messenger RNA may play an important role in the IgG2 deficiency of these patients.

Pulmonary hemosiderosis with hypersensitivity to buckwheat

BACKGROUNDnAdverse reactions after ingesting buckwheat are known to be IgE-mediated. Further, hypersensitivity reactions may be involved in some patients with pulmonary hemosiderosis related to cow milk sensitivity. We, however, encountered a patient with pulmonary hemosiderosis related to buckwheat protein without high levels of buckwheat-specific IgE antibodies.nnnOBJECTIVEnThe aim of this study was to investigate the mechanisms.nnnMETHODSnRAST for anti-buckwheat IgE, skin prick test, skin patch test, and proliferative responses of peripheral blood mononuclear cells to buckwheat were investigated in this patient.nnnRESULTSnRAST values for buckwheat protein were negative, and skin prick test for buckwheat protein also gave negative results. On the other hand, skin patch testing for buckwheat protein elicited positive responses. Further, peripheral blood mononuclear cells of our patient responded to buckwheat protein.nnnCONCLUSIONSnOur patient had pulmonary hemosiderosis related to non-immediate buckwheat protein hypersensitivity.

Microsatellite instability in B-cell lymphoma originating from Bloom syndrome.

Bloom syndrome (BS) is a rare autosomal recessive genetic disorder characterized by lupus‐like erythematous telangiectasias of the face, sun sensitivity, stunted growth infertility and immunodeficiency. In addition, BS patients are highly predisposed to cancers. Although recently the causative gene of BS (BLM) was identified as a DNA helicase homologue, the function of BLM in DNA replication has not been elucidated. In this study, p53 mutation and microsatellite instability in B‐cell lymphomas originating from 2 sibling BS patients were investigated. In the originally developed tumor of both patients, no p53 mutation was detected. In one patient, however, after treatment by ionizing radiation the B‐cell lymphoma recurred, showing a 9‐bp deletion in exon 7. In lymphoma cells and an EB‐virus‐transformed cell line from BS lymphocytes of this patient, microsatellite instability was also detected from the reduced length of microsatellite DNA markers, although in the other patient microsatellite instability was not detected. Thus, 2 B‐cell lymphomas, despite having the same BLM mutation, showed different phenotypes in terms of p53 mutation and microsatellite instability.

MAGNETIC RESONANCE IMAGING FOR EARLY DETECTION OF BRONCHIAL FOREIGN BODIES

Sir: The diagnosis of radiolucent bronchial foreign body aspiration is sometimes difficult. Conventional radiography may show mediastinal shadow shifting, hyperinflation and pneumomediastinum. However, these alterations are also caused by mucous plugs, and bronchial foreign bodies are often difficult to locate with precision. Tl-weighted MRI has recently been introduced to detect fat-rich bronchial foreign bodies such as peanuts, the most common foreign body in children [1-3]. Its usefulness is documented by the following case. A 2-year-old girl was admitted to our hospital with a l-week history of fever and cough. The patient had been treated for a common cold at another hospital. On admission, a coarse crackling sound was detected on the left side of the chest, and a plain radiograph showed an infiltration shadow in the lower left pulmonary field. A diagnosis of pneumonia was made and antibiotic therapy instituted. Her fever abated but chest radiographs revealed hyperinflation of the left lung and mediastinal shadow shifting from left to right upon expiration. Chest MRI was performed 1 week after admission. The Tl-weighted image showed a high-intensity area in the left main bronchus (Fig. 1A). Using direct rigid bronchoscopy, a peanut was extracted measuring 6 ~ 8 mm in length. The location of the peanut was consistent with the MRI finding. To confirm the applicability of Tl-weighted MRI, peanut fragments were incubated in saline for various periods of time and examined by MRI (Fig. 1B). They were identified at all times including the native state before incubation. Removal of a foreign body with a bronchoscope is easiest shortly after aspiration when it is not yet swollen, and when bronchial inflammation and check valve mechanisms have not yet developed. Tl-weighted MRI can be readily performed with oral sedatives or suppositories. It reduces the possibility of misdiagnosis Fig. 1 A Lung of a 2-year-old girl who had a 1-week history of fever and cough. Tl-weighted MRI shows a high-intensity area in the left main bronchus caused by an aspirated peanut. B Peanut fragments incubated in saline at 37 ~ for 0 (a), 3.5 (b), and 7 (c) days and human lower extremity

Two Japanese siblings with Bloom syndrome gene mutation and B-cell lymphoma.

Bloom syndrome (BS) is a rare autosomal recessive genetic disorder characterized by lupus-like erythematous telangiectasia of the face, sun sensitivity, infertility and stunted growth. Upper respiratory tract and gastrointestinal infections are commonly associated with the decreased immunoglobulin levels found in BS patients. Chromosomal abnormalities are hallmarks of the disorder, and high frequencies of sister chromatid exchanges and quadriradial configurations in lymphocytes and fibroblasts are virtually diagnostic. Recently, the causative gene for BS (BLM) has been identified. We encountered and defined a family with a nonsense mutation in BLM. The brother and sister were homozygous for the mutation and both developed B-cell malignant lymphoma in their twenties. These findings indicate the importance of prenatal diagnosis and the detection of BS carriers based on molecular genetic analysis.

Ataxia‐telangiectasia in the Japanese population: Identification of R1917X, W2491R, R2909G, IVS33+2T→A, and 7883del5, the latter two being relatively common mutations

We analyzed the data regarding six Japanese ataxia‐telangiectasia (A‐T) patients from four unrelated families, at the DNA level, to search for possible common mutations in the Japanese population. Among eight mutant alleles in the four families, c. 4612del165 (exon 33 skipping) was identified in two alleles, and c. 5749A to T (R1917X), c. 7471T to C (W2491R), c.7883del5, and c. 8725A to G (R2909G) were identified in one allele each. We found no mutations in the other two alleles. The IVS33+2T→A mutation was identified at the genomic level as the cause of exon 33 skipping. We also identified the IVS33+2T→A mutation in a Japanese patient ATL105 who was previously found to be a homozygote of c. 4612del165. W2491R and R2909G mutations were not detected in more than 100 control Japanese alleles. The latter is located in a highly conserved PI‐3 kinase domain and is a completely conserved residue among ATM‐related proteins. Taken together with previously documented mutations in five other Japanese A‐T patients, IVS33+2T→A and 7883del5 were identified in four and five alleles, respectively, in a total of 18 mutant alleles of Japanese A‐T patients. These results suggest that these two mutations are relatively common mutations in the Japanese population. Hum Mutat 12:338–343, 1998.© 1998 Wiley‐Liss, Inc.