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Serum IgM concentrations were low although serum IgG and IgA concentrations were normal in both our patients with Bloom's syndrome. Although the percentages of surface IgM-bearing cells were not reduced, the numbers of IgM-secreting cells were markedly reduced. The membrane-bound μ(μm) and secreted μ(μs) mRNAs are produced from transcripts of a single immunoglobulin μ gene by alternative RNA processing pathways. The control of μs mRNA synthesis depends on the addition of poly(A) to μs C-terminal segment. In both patients, μ mRNA was well detected but μs C-terminal mRNA was scarcely detected, suggesting that μm mRNA was well transcribed but μs mRNA was not. There was, at least, no mutation or deletion in the μs C-terminal coding sequence, the RNA splice site (GG/TAAAC) at the 5' end of μs C-terminal segment and the AATAAA poly(A) signal sequence in both patients. Our results suggest that selective IgM deficiency in Bloom's syndrome is due to an abnormality in the maturation of surface IgM-bearing B cells into IgM-secreting cells and a failure of μs mRNA synthesis. Moreover, reduced μs mRNA synthesis may be due to the defect on developmental regulation of the site at which poly(A) is added to transcripts of the μ gene. [ABSTRACT FROM AUTHOR]

In most patients with Bloom's syndrome (BS). selective IgM deficiency is commonly found. We examined proliferative responses by incorporation of [3H]-thymidine and the production of immunoglobulin after ultraviolet B (UVB) irradiation in the cells of two patients with BS. With regard to the proliferative responses in peripheral blood mononuclear cells (PBMC) cultured with pokeweed mitogen (PWM), the patients" PBMC were more sensitive to UVB irradiation than controls. Although the effect of UVB irradiation in lymphoblastoid cell lines (LCL) after 0 days of culture showed no difference between one patient and controls, the patient's LCL were more sensitive to UVB than the controls after 3 and 7 days of culture. These results suggest that the proliferative responses of the patient's LCL recovered later than those of controls. IgM production was the most sensitive to UVB in the patients' PBMC and LCL. IgG and IgA production in the patients' PBMC and LCL showed the same sensitivity as controls. From our results, it is suspected that the preferential damage to IgM production by UVB is connected with the selective IgM deficiency of BS. [ABSTRACT FROM AUTHOR]

We report a case of common variable immunodeficiency (CVI) that shows low levels of IgG and IgA, but a normal quantitative or qualitative level of IgM. T-cell functions were not disturbed. Increased numbers of surface IgM (sIgM) and sIgD, sIgM and sIgG, sIgM and sIgA double-bearing B cells were observed as compared with a control. No IgG and IgA induction upon stimulation with Staphylococcus aureus Cowan I (SAC) and recombinant interleukin-2 (rIL-2), or pokeweed mitogen (PWM) and rIL-4 or rIL-6 was observed, although there was proliferation. Although μmRNA was expressed as much as in a healthy control, transcription of γ mRNA and a mRNA was very low. Furthermore, no enhanced effects of γ mRNA and α mRNA were recognized upon stimulation with rIL-4 and rIL-6. These results suggest that the patient's B cells might be defective at the switching process from μ, μ and δ, μ and γ to γ or μ and α to α. [ABSTRACT FROM AUTHOR]

Five heterogeneous IgA-immunodeficient patients were analysed for expression of the α-chain gene. The number of surface IgA-bearing B cells was low in four patients. Southern blot analysis indicated no deletion of immunoglobulin structural genes coding for Cα or α switching-region genes. The number of surface IgM and IgA double-bearing B cells increased in some patients. Addition of recombinant interleukin 4 (rIL-4), rIL-5, and rIL-6 to the normal B cells enhanced IgA production. However, B cells of the patients showed no or one-third lower IgA production in response to these lymphokines, even though there was proliferation, rIL-4, rIL-5, rIL-6 induced low or no expression of α mRNA of the patients' B cells. These results suggested that the patients lacked B cells able to produce transcripts for the IgA heavy chain, and that some patients' B cells might be defective at the switch-recombination process from α to α from α and α to α. [ABSTRACT FROM AUTHOR]

Growing evidence suggests that oral health may be an important factor associated with cognitive function in aged populations. However, many previous studies on this topic used insensitive oral indicators or did not include certain essential covariates. Thus, we examined the association between occlusal force and cognitive function in a large sample of older adults, controlling for dietary intake, vascular risk factors, inflammatory biomarkers, depression, and genetic factors.In this cross-sectional study of older community-dwelling Japanese adults, we examined data collected from 994 persons aged 70 years and 968 persons aged 80 years. Cognitive function was measured using the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Oral status and function were evaluated according to the number of remaining teeth, periodontal pocket depth, and maximal occlusal force. Associations between MoCA-J scores and occlusal force were investigated via bivariate and multivariate analyses.Education level, financial status, depression score, and intake of green and yellow vegetables, as well as number of teeth and occlusal force, were significantly correlated with MoCA-J scores in both age groups. Among individuals aged 80 years, CRP and periodontal status were weakly but significantly associated with MoCA-J score. After controlling for all significant variables via bivariate analyses, the correlation between maximal occlusal force and cognitive function persisted. A path analysis confirmed the hypothesis that cognitive function is associated with occlusal force directly as well as indirectly via food intake.After controlling for possible factors, maximal occlusal force was positively associated with cognitive function directly as well as indirectly through dietary intake.

Background: The TERMINAL FLOWER 1 (TFL1) gene of Arabidopsis plays an important role in regulating flowering time and in maintaining the fate of inflorescence meristem (IM). TFL1 is a homologue of CENTRORADIALIS (CEN) from Antirrhinum, which is only involved in IM maintenance. Recent mutational studies and the genome project revealed that TFL1 belongs to a small gene family in Arabidopsis, in which functional divergence may have occurred among the members., Results: We found a new member of the TFL1 gene family, which is mapped on chromosome 2 of Arabidopsis. The predicted protein sequence encoded by this gene is more closely related to that of CEN than other Arabidopsis TFL1 homologues (and therefore named ATC for Arabidopsis thaliana CENTRORADIALIS homologue). Transgenic plants constitutively expressing the ATC gene (35S:ATC), in either wild-type or tfl1 mutant backgrounds, showed a phenotype similar to that observed in transgenic plants constitutively expressing the TFL1 gene. However, in contrast to TFL1, the expression of ATC was only detected in the hypocotyl of young plants, and not in the IM. In addition, an atc loss-of-function mutant, isolated by screening a T-DNA library, showed no phenotypes that were similar to those of tfl1 mutants., Conclusion: The phenotypes of transgenic plants over-expressing ATC suggest that the ATC protein can functionally substitute for TFL1. However, the pattern and level of expression and the loss-of-function phenotype indicate that ATC does not participate in the regulation of IM identity, but rather has a role that is different from that of TFL1.

Variegated leaves are often caused by a nuclear recessive mutation in higher plants. Characterization of the gene responsible for variegation has shown to provide several pathways involved in plastid differentiation. Here we describe an Arabidopsis variegated mutant isolated by T-DNA tagging. The mutant displayed green and yellow sectors in all green tissues except for cotyledons. Cells in the yellow sector of the mutant contained both normal-appearing and mutant chloroplasts. The isolated mutant was shown to be an allele of the previously reported mutant, yellow variegated (var2). Cloning and molecular characterization of the VAR2 locus revealed that it potentially encodes a chloroplastic homologue of FtsH, an ATP-dependent metalloprotease that belongs to a large protein family involved in various cellular functions. ftsH-like genes appear to comprise a small gene family in Arabidopsis genome, since at least six homologues were found in addition to VAR2. Dispensability of VAR2 was therefore explained by the redundancy of genes coding for FstHs. In the yellow regions of the mutant leaves, accumulation of photosynthetic protein components in the thylakoid membrane appeared to be impaired. Based on the role of FtsH in a protein degradation pathway in plastids, we propose a possibility that VAR2 is required for plastid differentiation by avoiding partial photooxidation of developing chloroplasts.

A cDNA clone, 4B-1, previously isolated by differential screening is preferentially expressed in floral organs of Arabidopsis thaliana. Characterization of the full length cDNA and the genetic locus corresponding to 4B-1 cDNA revealed that it potentially encodes a myrosinase binding protein (MBP) which is presumably present in a large myrosinase complex. The deduced amino acid sequence of the polypeptide encoded by cDNA clone (designated f-AtMBP) appeared to consist of two parts: one region at the C-terminal half representing overall homology with AtMBP, an MBP homologue in A. thaliana, and the other at an extended N-terminal region of about 150 amino acids showing significant identity with the N-terminal region of the MBP-related protein reported in Brassica. Expression analysis by RNA blot and in situ hybridization showed that f-AtMBP was specifically expressed in floral meristems, pistils, stamens, petals, and ovules of immature flowers, but no expression was observed in the specialized cells called the myrosin cells in the hypocotyl and cotyledons of developing seeds where myrosinase enzymes are normally found. Although MBPs and MBP-related proteins are considered to be inducible by exogenous application of signal molecules and physical wounding, we found that f-AtMBP expression was not activated by such treatment, suggesting that f-AtMBP is a novel type of MBP specific to floral organs.

A highly abundant repetitive DNA sequence family of Arabidopsis, AtCon, is composed of 178-bp tandemly repeated units and is located at the centromeres of all five chromosome pairs. Analysis of multiple copies of AtCon showed 95% conservation of nucleotides, with some alternative bases, and revealed two boxes, 30 and 24 bp long, that are 99% conserved. Sequences at the 3' end of these boxes showed similarity to yeast CDEI and human CENP-B DNA-protein binding motifs. When oligonucleotides from less conserved regions of AtCon were hybridized in situ and visualized by using primer extension, they were detected on specific chromosomes. When used for polymerase chain reaction with genomic DNA, single primers or primer pairs oriented in the same direction showed negligible amplification, indicating a head-to-tail repeat unit organization. Most primer pairs facing in opposite directions gave several strong bands corresponding to their positions within AtCon. However, consistent with the primer extension results, some primer pairs showed no amplification, indicating that there are chromosome-specific variants of AtCon. The results are significant because they elucidate the organization, mode of amplification, dispersion, and evolution of one of the major repeated sequence families of Arabidopsis. The evidence presented here suggests that AtCon, like human alpha satellites, plays a role in Arabidopsis centromere organization and function.

We have previously identified two cDNAs encoding vegetative storage proteins (VSPs) in Arabidopsis thaliana. Unlike soybean in which VSPs accumulate at high levels in leaves, A. thaliana VSP mRNAs are abundant in flowers. To understand tissue-specific expression and possible roles of VSPs on reproductive organ development, genes corresponding to VSPs (Vsp1 and Vsp2) and their putative promoters were characterized in this study. Genomic sequence analysis revealed that Vsp1 and Vsp2 resemble each other except in their introns, and that these two genes were organized in a tandem array with an interval of 6 kb in a region. The expression patterns of Vsp1 and Vsp2 were examined using transgenic A. thaliana plants carrying a promoter from Vsp1 or Vsp2 fused to a bacterial beta-glucuronidase (GUS) reporter gene. The promoter from Vsp1 expressed its effect in gynoecia, especially in styles, the basal and distal ends of ovaries and in siliques, whereas the promoter from Vsp2 showed its activity in vegetative shoots, petioles, peduncles and receptacles of floral organs. These results suggest that expression of Vsp1 and Vsp2 may be developmentally regulated in A. thaliana. In the transgenic plants, the GUS activity was induced by wounding in an area around the mid-rib of leaves. Therefore, Vsp1 and Vsp2 promoters appear to have elements required for both tissue specificity and wounding.

Properties of an unusual atp9-rpl16 cotranscript preferentially found in the maternal distorted leaf mutant of Arabidopsis thaliana, which had arisen from a genetic cross between chloroplast mutator and wild-type plants, were examined. Analysis of RNA editing of this cotranscript showed that one editing event in the rpl16 coding region created a UGA stop codon. This raises a possibility that a downstream GUG codon can serve as an initiation codon for rpl16.

The 5S ribosomal RNA genes were mapped to mitotic chromosomes of Arabidopsis thaliana by fluorescence in situ hybridization (FISH). In the ecotype Landsberg erecta, hybridization signals appeared on three pairs of chromosomes, two of which were metacentric and the other acrocentric. Hybridization signals on one pair of metacentric chromosomes were much stronger than those on the acrocentric and the other pair of metacentric chromosomes, probably reflecting the number of copies of the genes on the chromosomes. Other ecotypes, Columbia and Wassilewskija, had similar chromosomal distribution of the genes, but the hybridization signals on one pair of metacentric chromosomes were very weak, and detectable only in chromosomes prepared from young flower buds. The chromosomes and arms carrying the 5S rDNA were identified by multi-color FISH with cosmid clones and a centromeric 180 bp repeat as co-probes. The metacentric chromosome 5 and its L arm carries the largest cluster of the genes, and the short arm of acrocentric chromosome 4 carries a small cluster in all three ecotypes. Chromosome 3 had another small cluster of 5S rRNA genes on its L arm. Chromosome 1 and 2 had no 5S rDNA cluster, but they are morphologically distinguishable; chromosome 1 is metacentric and 2 acrocentric. Using the 5S rDNA as a probe, therefore, all chromosomes of A. thaliana could be identified by FISH. Chromosome 1 is large and metacentric; chromosome 2 is acrocentric carrying 18S-5.8S-25S rDNA clusters on its short arm; chromosome 3 is metacentric carrying a small cluster of 5S rDNA genes on its L arm; chromosome 4 is acrocentric carrying both 18S-5.8S-25S and 5S rDNAs on its short (L) arm; and/chromosome 5 is metacentric carrying a large cluster of 5S rDNA on its L arm.

Seventeen cDNA clones of genes corresponding to mRNAs expressed preferentially in floral organs of Arabidopsis thaliana were obtained by differential screening of a flower bud cDNA library, and classified into five groups (1A, 17A, 1B, 4B and 5B) by cross-hybridization and restriction analysis. Sequence analysis revealed that the 1A-1 and 17A-1 clones encode vegetative storage proteins (VSPs). The VSP mRNAs were detected in a small amount in leaves and increased to a limited level by wounding. Both 1B-1 and 5B-1 clones were homologous to transmembrane protein cDNAs. The protein encoded by 4B-1 clone contained a proline-rich region, but no homologous proteins were found in databases.

Chloroplast mutator (chm) of Arabidopsis is a recessive nuclear mutation that causes green and white variegation in leaves and is inherited in a non-Mendelian fashion. In this study, we have identified and characterized a mutant observed in F1 and backcrossed BC1 populations from a cross between chm1-3 and ecotype Columbia. This mutant, maternal distorted leaf (MDL), grows very poorly and is distinguished by distorted rough leaves and aborted flowering organs. Electron microscopic observation showed that in MDL plants, a significant portion of mitochondria are abnormal and appear to be nonfunctional. DNA gel blot and sequence analysis of the MDL mitochondrial DNA (mtDNA) revealed rearrangements in two mtDNA fragments associated with rps3-rpl16 genes (encoding ribosomal proteins S3 and L16, respectively). One rearrangement resulted in the insertion of the rps3-rpl16 operon downstream of atp9. An independent deletion in this region had eliminated the majority of rps3. In contrast, another rearrangement deleted part of rpl16, whereas rps3 remained intact. RNA gel blot analysis indicated that expression of these genes is also altered as a consequence of the mtDNA rearrangements. Thus, a mutation at the CHM locus affects mitochondrial gene expression, and impaired mitochondrial function may result in the distorted phenotype.

The localization of protein kinase C (PKC) was investigated in B cells or B cell lines derived from patients with common variable immunodeficiency (CVI) and healthy controls. Stimulation of the healthy control B cells by phorbol ester or anti-mu induced PKC activation and translocation to the plasma membrane after 10 min. In contrast, in the CVI-B cells, no apparent PKC translocation was induced by either phorbol ester or anti-mu stimulation. These results suggest that the pathogenesis in some CVI patients might involve defects in the pathway of PKC activation.

The gene Tm-2 (tomato mosaic virus (ToMV) resistant), which is tightly linked to a morphological marker gene nv (netted virescent), resides in a heterochromatic region near the centromere of chromosome 9 in tomato. Tm-2 and Tm-2a are known to be allelic, and exhibit similar phenotypes to each other, but can be differentiated by their response to different ToMV strains. An inoculation experiment demonstrated that Tm-2 helped a mutant strain of ToMV to infect a heterozygous tomato (Tm-2/Tm-2a). Aiming at investigating the structures of DNA around these active genes and their influence on gene activities, we attempted to identify and characterize random amplified polymorphic DNA (RAPD) markers linked to these genes using nearly isogenic lines (NILs) of tomato. Genetic analysis using 13 RAPD markers linked to the Tm-2 locus and cytological analysis by fluorescence in situ hybridization (FISH) demonstrated that the lines resistant to ToMV had a large block derived from a chromosome of Lycopersicon peruvianum. Among these markers, we estimated that two, OPE16(900) and OPN31(1000), are nearest to the Tm-2 locus. Out of the 13 markers six, distributed within about 0.7 centi-Morgan (cM), were cloned and sequenced to be converted to sequence characterized amplified region (SCAR) markers. Of these, four were successfully converted to SCAR markers. The six clones were also used as probes for Southern hybridization of genomic DNA from NILs to characterize structures around the Tm-2 locus. One clone was estimated to be derived from a sequence that was present in one copy. The other five clones appeared to be derived from different kinds of moderately or highly repetitive sequences.

Hepatitis B virus (HBV) carriers usually produce antibody to HB core antigen (anti-HBc). We present the case of an HBV carrier who has lacked anti-HBc for a 2-year observation period. Antibody titers against several common viruses (herpes simplex virus-1, varizella-zoster virus and Epstein-Barr virus) were detected in his serum. His lymphocytes proliferated in vitro in response to phytohemagglutinin and concanavalin A. In contrast to other naturally immune or chronic HBV carriers, anti-HBc was not produced by his peripheral mononuclear cells (PBMC) in culture supernatant of pokeweed mitogen-induced anti-HBc production system. These results suggested that he was in a state of impaired specific antibody response to HB core antigen (HBcAg).

Selective IgM deficiency is commonly found in Bloom's syndrome (BS). We reported that membrane-bound mu (micron(s)) mRNA was well transcribed but secreted mu (microseconds) mRNA was not, although there was no mutation or deletion in the sequence including the microseconds C-terminal coding sequence in the patients with BS. Furthermore, we have shown previously, preferential damage to IgM production by ultraviolet (UV) irradiation of the cells of the patient. In the study described here, mutation in the sequence which is upstream of the 5' end of the microseconds C-terminal coding sequence was induced by UV irradiation in the lymphoblastoid cell line (LCL) of BS patient. These results suggest that abnormal repair of DNA damage is present in this LCL, and that preferential damage to IgM production by UV irradiation in this LCL may be due to the abnormal repair of DNA damage.

Two highly repetitive DNA sequences have been cloned from Arabidopsis thaliana, ecotype Columbia, and were characterized by molecular and cytological analyses. These two sequences belong to the same repeat family with 180-bp basic unit, being tandemly organized in clusters. Pulsed field gel electrophoresis showed that this repeat sequence family forms at least seven clusters from ca. 100 to 1200 kb in length and ca. 3500 kb in total. Fluorescent in situ hybridization to somatic metaphase cells with the monomeric repeat unit as a probe clearly revealed that this repeat family is located at the centromeric regions of all chromosomes. It was also shown that this repetitive sequence is closely associated with limited parts of heterochromatic blocks on the centromeric regions which are visible distinctly at meiotic prophase from leptotene to diakinesis. Furthermore, this sequence hybridized preferentially to both polar sides of five bivalent chromosomes at the first metaphase. These results suggest that the repetitive sequences of this family were derived from the regions very close to the centromeres or on the centromeres themselves.

We evaluated the production of interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) in peripheral blood lymphocytes (PBLs) from six patients with common variable immunodeficiency (CVID). IL-2 production and IFN-gamma concentrations were not reduced in these patients. As the production of IL-2 and IFN-gamma secreted from TH1 clones was within the normal range in patients with CVID, we concluded that TH1 function was normal in these patients. Our previous report showed B-cell dysfunction in CVID patients. Therefore, we concluded that the immune defect in these patients is caused by B-cell dysfunction rather than T-cell dysfunction.

Selective IgM deficiency is found commonly in patients with Bloom's syndrome (BS). Serum IgM concentrations were low though serum IgG and IgA concentrations were normal in both patients with BS included in the study. In a previous study the authors showed that selective IgM deficiency in BS is due to an abnormality in the maturation of surface IgM-bearing cells into IgM-secreting cells and a failure of secreted mu (mu s) mRNA synthesis. The membrane-bound mu (mu m) and mu s mRNA are produced from transcripts of a single immunoglobulin mu gene by alternative RNA processing pathways. The control of mu s mRNA synthesis depends on the addition of poly(A) to mu s C-terminal segment. The study described here demonstrated that there was no mutation or deletion in the sequence including mu s C-terminal coding sequence, the RNA splice site (GG/TAAAC) at the 5' end of mu s C-terminal segment, and the AATAAA poly(A) signal sequence, and second GT-rich element immediately down-stream of the cleavage site in both patients.

We investigated the production of immunoglobulin (Ig) in six patients with common variable immunodeficiency and analyzed the courses of their levels of serum Ig for a period of 8-13 years. In all patients, levels of serum IgM, IgG and IgA were markedly low at the first examination, except for the IgM level in one patient. Improvement of serum Ig levels was observed in the patients in whom Ig production of non-T cells at the first examination and C mu gene expression had been detected to a slight degree, but serum Ig levels remained low in the patients in whom Ig production of non-T cells and C mu gene expression had not been detected. Our results suggest that some hypogammaglobulinemia in common variable immunodeficiency develops or improves with age.

The role of T lymphocytes was assessed in patients with food-sensitive atopic dermatitis (AD). T lymphocytes plus monocytes responded well to ovalbumin or bovine serum albumin (BSA) in children with AD who were sensitive to hen's egg or cow's milk compared with healthy children and children with immediate allergic symptoms who are sensitive to hen's egg or cow's milk. The responding cells were shown to be predominantly CD4+ T lymphocytes. Interleukin-2 activity and interferon-gamma concentrations in culture supernatants of ovalbumin-stimulated peripheral blood mononuclear cells (PBMCs) from patients with AD who were sensitive to hen's egg were significantly higher than those of healthy children and patients sensitive to hen's egg with immediate symptoms. Expression of Fc epsilon R II on B lymphocytes in cultures of ovalbumin-stimulated PBMCs from patients with AD was significantly higher than that of healthy children, but it tended to be lower than that of patients with immediate symptoms. These results suggest that, in patients with AD who are food sensitive, CD4+ T lymphocytes stimulated by food antigens secrete lymphokines such as interleukin-2 and interferon-gamma that are secreted from TH1 clones in mice, and express Fc epsilon R II on B lymphocyte that is induced by interleukin-4 secreted from TH2 clones in mice. Taken together, cell-mediated immunity may also occur in addition to IgE-mediated hypersensitivity in patients with food-sensitive AD.

Five patients with common variable immunodeficiency treated in our hospital between December 1979 and December 1990 were given six kinds of intravenous immunoglobulin preparations (pepsin treated, S-sulfonated, polyethylene glycol treated, pH4 treated, alkylated, and pH4.25 formulation preparation) for replacement therapy. Duration of the therapy ranged from 7.6 to 11 years. Incidences of fever and acute infections were variable among patients, but no significant differences were seen in the incidences among periods given each preparation. Three cases revealed abnormal pulmonary functions in tests. Adverse reactions were rarely seen in our study periods, and no severe reactions were observed. No significant differences were seen in incidences of adverse reactions. Postinfusion levels of serum complement slightly decreased from preinfusion levels. However, the decrease in complement was not related to any adverse reaction. No long-term complications such as transmission of hepatitis have been observed. Our data suggest that no obvious differences exist between the efficacy and safety of each IVIG preparation. Differences of efficacy of IVIG replacement therapy may be due to the variable pathophysiology of each patient.

Three patients with common variable immunodeficiency (CVID) were analyzed for translation from mu mRNA by the cell-free translation method and for expression of mu mRNA by northern blotting. In cases 1 and 2, the mu chain was not detected in the products by cell-free translation nor was mu mRNA detected by northern blotting. In case 3, mu mRNA was detected at a low level. This suggests that the disorders occur between rearrangement of the Ig genes and transcription of the C mu gene in cases 1 and 2, and that the functions of rearrangement and transcription are qualitatively preserved to a certain degree in case 3. Thus, the pathogeneses of CVID are variable and more research on regulatory mechanisms of B cell development is necessary to understand each case of CVID.

The carbohydrate moieties of glycoproteins in plasma membrane are known to correlate with the induction of cell differentiation in some kinds of cells. We investigated the asparagine-linked sugar chains of neuroblastoma and ganglioneuroma cell membranes. The acidic oligosaccharides were bi-, tri-, and tetraantennary complex-type sugar chains with Man alpha-->(Man alpha)Man beta-->GlcNAc beta-->(+/- Fuc alpha-->)GlcNAc as their cores. A comparative study of the oligosaccharides of these cells showed that the biantennary complex-type sugar chain with bisecting N-acetylglucosamine residues increased and high-molecular-weight oligosaccharides decreased in ganglioneuroma cells. It is suspected that asparagine-linked sugar chains correlate with the differentiation stage of neuroblastoma.

Six heterogeneous common variable immunodeficiency (CVID) patients were analysed for germ-line DNA, DNA rearrangements, and RNA expressions of immunoglobulin (Ig) gene by Southern or northern blotting using appropriate probes. We detected no polymorphism in neutrophil DNA hybridized to a C mu and a C gamma probe. In three patients, both serum Ig and Ig-bearing cells were scarcely detected, and by northern hybridization methods, neither mu mRNA, gamma mRNA, alpha mRNA nor kappa mRNA was detected. However, one Epstein-Barr virus-transformed B lymphoblastoid cell line (LCL) of these three patients was different from the germ line in the region of JH, C gamma, and C kappa, and expressed mu mRNA at a higher level. The B cell defects of these three patients lay on the B cell maturation stage similar to X-linked agammaglobulinaemia (XLA). In two others among the six CVID patients, serum IgM and IgM-bearing cells were detected to a certain degree, and by northern hybridization, mu mRNA was detected at a lower level, but neither mu mRNA, alpha mRNA, nor kappa mRNA was detected. One LCL of these two patients could express mu mRNA at the normal level. In the last patient, the serum IgM was normal, serum IgG and IgA were somewhat low, Ig-bearing cells were normal, mu mRNA and kappa mRNA were detected at the normal level, and gamma mRNA and alpha mRNA were detected at a lower level. The defect of this patient affected the class switch stage. These results showed that primary B cell defects in CVID occurred at several B cell differentiation stages which could be classified by expression of the Ig gene, and at the degree of clonal diversity in the B cell repertoire. Furthermore, this study provides support for the idea that the CVID defect is related to a more generalized cellular function, such as regulating the proliferation and/or clonal expansion of cells of the B lymphoid lineage.

Serum IgM concentrations were low although serum IgG and IgA concentrations were normal in both our patients with Bloom's syndrome. Although the percentages of surface IgM-bearing cells were not reduced, the numbers of IgM-secreting cells were markedly reduced. The membrane-bound mu (microns) and secreted mu (microseconds) mRNAs are produced from transcripts of a single immunoglobulin mu gene by alternative RNA processing pathways. The control of microseconds mRNA synthesis depends on the addition of poly(A) to microseconds C-terminal segment. In both patients, mu mRNA was well detected but microseconds C-terminal mRNA was scarcely detected, suggesting that microns mRNA was well transcribed but microseconds mRNA was not. There was, at least, no mutation or deletion in the microseconds C-terminal coding sequence, the RNA splice site (GG/TAAAC) at the 5' end of microseconds C-terminal segment and the AATAAA poly(A) signal sequence in both patients. Our results suggest that selective IgM deficiency in Bloom's syndrome is due to an abnormality in the maturation of surface IgM-bearing B cells into IgM-secreting cells and a failure of microseconds mRNA synthesis. Moreover, reduced microseconds mRNA synthesis may be due to the defect on developmental regulation of the site at which poly(A) is added to transcripts of the mu gene.

Many reports have shown that expression of the c-myc protooncogene represents an early event of lymphocyte activation. Calcium influx and activation of protein kinase C synergistically bypass the early signal transduction of lymphocyte activation. In this study, the c-myc message of B cells or B cell lines stimulated by 12-o-tetradecanoylphorbol-13-acetate (TPA), A23187, Staphylococcus aureus Cowan I (SAC), or anti-mu was not expressed or was poorly expressed in common variable immunodeficiency (CVID) patients whose B cells did not differentiate or only poorly differentiated to SAC plus recombinant interleukin 2, whereas the c-myc message of 1 CVID patient's B cells that differentiated well in IgM secretion to SAC plus recombinant interleukin 2 was well expressed when stimulated by TPA, A23187, SAC, or anti-mu. These results suggest that an abnormality exists in the early signal transduction process on some CVID patients' B cells and that it may be in the bypass by calcium influx and direct activation of protein kinase C.

In both healthy controls and patients with Wiskott-Aldrich syndrome, the main oligosaccharide in asparagine-linked sugar chains of the membrane glycoproteins of erythrocytes was biantennary sugar chain with bisected GlcNAc (Gal2-GlcNAc2-Man3-GlcNAc-GlcNAc-Fuc-GlcNAcOT). Biantennary sugar chain with an alpha-fucosyl residue linked at the proximal GlcNAc was seen but biantennary sugar chain without an alpha-fucosyl residue at the proximal GlcNAc was not detected in each subject. There was no difference in quality and quantity of asparagine-linked sugar chains of erythrocyte membrane glycoproteins between healthy controls and the patients. These results suggest that asparagine-linked sugar chains in membrane glycoproteins of hematopoietic cells may not be impaired in Wiskott-Aldrich syndrome.