Persistence of immunoglobulin heavy chain/c-myc recombination-positive lymphocyte clones in the blood of human immunodeficiency virus-infected homosexual men.

We studied blood lymphocytes of human immunodeficiency virus (HIV)-seropositive and -negative homosexual men for the presence of T(8;14) translocations that recombine c-myc and immunoglobulin heavy-chain (IgH) mu/IgH alpha switch regions. Clones with T(8;14) translocations were detected in 10.5% (12/114) of the HIV-positive and in 2.0% of the 99 uninfected patients. The majority of recombinations were found at a single time point only. Four patients, however, harbored multiple (up to four) and persistent (up to 9 years) translocation-positive cell clones. No correlation between the presence of these aberrant lymphocytes and a later lymphoma could be established. The exon 1/intron 1 region of the recombined c-myc was investigated for the presence of point mutations and these were found in the nonpersistent clones. Additional alterations detected in these clones included duplications and a deletion in the c-myc gene. The pattern of base substitution indicates that they were introduced after the translocation event.

Pax5 (BSAP) regulates the murine immunoglobulin 3' alpha enhancer by suppressing binding of NF-alpha P, a protein that controls heavy chain transcription.

The Pax5 transcription factor BSAP (B-cell-specific activator protein) is known to bind to and repress the activity of the immunoglobulin heavy chain 3' alpha enhancer. We have detected an element--designated alpha P--that lies approximately 50 bp downstream of the BSAP binding site 1 and is required for maximal enhancer activity. In vitro binding experiments suggest that the 40-kDa protein that binds to this element (NF-alpha P) is a member of the Ets family present in both B-cell and plasma-cell nuclei. However, in vivo footprint analysis suggests that the alpha P site is occupied only in plasma cells, whereas the BSAP site is occupied in B cells but not in plasma cells. When Pax5 binding to the enhancer in B cells was blocked in vivo by transfection with a triple-helix-forming oligonucleotide an alpha P footprint appeared and endogenous immunoglobulin heavy chain transcripts increased. The triple-helix-forming oligonucleotide also increased enhancer activity of a transfected construct in B cells, but only when the alpha P site was intact. Pax5 thus regulates the 3' alpha enhancer and immunoglobulin gene transcription by blocking activation by NF-alpha P.

The Lutheran blood group glycoprotein, another member of the immunoglobulin superfamily, is widely expressed in human tissues and is developmentally regulated in human liver.

Glycoproteins expressing the Lutheran blood group antigens were isolated from human erythrocyte membranes and from human fetal liver. Amino acid sequence analyses allowed the design of redundant oligonucleotides that were used to generate a 459-bp, sequence-specific probe by PCR. A cDNA clone of 2400 bp was isolated from a human placental lambda gt 11 library and sequenced, and the deduced amino acid sequence was studied. The predicted mature protein is a type I membrane protein of 597 amino acids with five potential N-glycosylation sites. There are five disulfide-bonded, extracellular, immunoglobulin superfamily domains (two variable-region set and three constant-region set), a single hydrophobic, membrane-spanning domain, and a cytoplasmic domain of 59 residues. The overall structure is similar to that of the human tumor marker MUC 18 and the chicken neural adhesion molecule SC1. The extracellular domains and cytoplasmic domain contain consensus motifs for the binding of integrin and Src homology 3 domains, respectively, suggesting possible receptor and signal-transduction function. Immunostaining of human tissues demonstrated a wide distribution and provided evidence that the glycoprotein is under developmental control in liver and may also be regulated during differentiation in other tissues.

Strand specificity in the transcriptional targeting of recombination at immunoglobulin switch sequences.

B-lymphocyte-specific class switch recombination is known to occur between pairs of 2- to 10-kb switch regions located immediately upstream of the immunoglobulin constant heavy-chain genes. Others have shown that the recombination is temporally correlated with the induction of transcription at the targeted switch regions. To determine whether this temporal correlation is due to a mechanistic linkage, we have developed an extrachromosomal recombination assay that closely recapitulates DNA deletional class switch recombination. In this assay, the rate of recombination is measured between 24 and 48 hr posttransfection. We find that recombinants are generated in a switch sequence-dependent manner. Recombination occurs with a predominance within B-cell lines representative of the mature B-cell stage and within a subset of pre-B-cell lines. Transcription stimulates the switch sequence-dependent recombination. Importantly, transcription activates recombination only when directed in the physiologic orientation but has no effect when directed in the nonphysiologic orientation.

Prolactin-immunoglobulin G complexes from human serum act as costimulatory ligands causing proliferation of malignant B lymphocytes.

Several lines of evidence indicate that immunoglobulin-bound prolactin found in human serum is not a conventional complex between an anti-prolactin antibody and prolactin but a different type of association of prolactin with the Fab portion of IgG heavy chains. The complex of prolactin with IgG was purified from serum by anti-human prolactin affinity chromatography and was shown to contain close to 1 mole of N epsilon-(gamma-glutamyl)lysine crosslinks per mole of complex, a characteristic feature in structures crosslinked by transglutaminase. Interestingly, the complex caused a proliferation of cells from a subset of patients with chronic lymphocytic leukemia, while it was inactive in a cell proliferation prolactin bioassay. By contrast, human prolactin stimulated the proliferation of cells in the bioassay but had no effect on the complex-responsive cells from the patients. Competition studies with prolactin and free Fc fragment of IgG demonstrated a necessity for engaging both the prolactin and the immunoglobulin receptors for proliferation. More importantly, competition for the growth response by free prolactin and IgG suggests both possible reasons for the slow growth of this neoplasm as well as avenues for control of the disease.

Interleukin-6-deficient mice are highly susceptible to Giardia lamblia infection but exhibit normal intestinal immunoglobulin A responses against the parasite.

In the present study, interleukin-6 (IL-6)-deficient mice were infected with Giardia lamblia clone GS/M-83-H7. Murine IL-6 deficiency did not affect the synthesis of parasite-specific intestinal immunoglobulin A. However, in contrast to wild-type mice, IL-6-deficient animals were not able to control the acute phase of parasite infection. Reverse transcription-PCR-based quantitation of cytokine mRNA levels in peripheral lymph node cells exhibited a short-term up-regulation of IL-4 expression in IL-6-deficient mice that seemed to be associated with failure in controlling the parasite population. This observation suggests a further elucidation of IL-4-dependent, Th2-type regulatory processes regarding their potential to influence the course of G. lamblia infection in the experimental murine host.

Cytomegalovirus Immunoglobulin After Thoracic Transplantation: An Overview

Cytomegalovirus (CMV) is a highly complex pathogen which, despite modern prophylactic regimens, continues to affect a high proportion of thoracic organ transplant recipients. The symptomatic manifestations of CMV infection are compounded by adverse indirect effects induced by the multiple immunomodulatory actions of CMV. These include a higher risk of acute rejection, cardiac allograft vasculopathy after heart transplantation, and potentially bronchiolitis obliterans syndrome in lung transplant recipients, with a greater propensity for opportunistic secondary infections. Prophylaxis for CMV using antiviral agents (typically oral valganciclovir or intravenous ganciclovir) is now almost universal, at least in high-risk transplants (D+/R-). Even with extended prophylactic regimens, however, challenges remain. The CMV events can still occur despite antiviral prophylaxis, including late-onset infection or recurrent disease, and patients with ganciclovir-resistant CMV infection or who are intolerant to antiviral therapy require alternative strategies. The CMV immunoglobulin (CMVIG) and antiviral agents have complementary modes of action. High-titer CMVIG preparations provide passive CMV-specific immunity but also exert complex immunomodulatory properties which augment the antiviral effect of antiviral agents and offer the potential to suppress the indirect effects of CMV infection. This supplement discusses the available data concerning the immunological and clinical effects of CMVIG after heart or lung transplantation

Sequences of immunoglobulin chains : tabulation and analysis of amino acid sequences of precursors, V-regions, C-regions, J-chain and -microglobulins /

1976 ed. issued under title: Variable regions of immunoglobulin chains.

The properties of CpG islands in the putative promoter regions of human immunoglobulin (Ig) genes

CpG island is a GC-rich motif occurred in gene promoter region, which can play important roles in gene silencing and imprinting. Here, we present a set of discriminant functions that can recognize the structural and compositional features of CpG islands in the putative promoter regions (PPRs) of human and mouse immunoglobulin (Ig) genes. We showed that the PPRs of both human and mouse Ig genes irrespective of gene chromosomal localization are apparently CpG island poor, with a low percentage of the CpG islands overlapped with the transcription start site (TSS). The human Ig genes that have CpG islands in the PPRs show a very narrow range of CpG densities. 47% of the Ig genes fall in the range of 3.5-4 CpGs/100 bp. In contrast, the non-Ig genes examined have a wide range of the density of CpG island, with 10.5% having the density of 8.1-15 CpGs/100 bp. Meantime, five patterns of the CpG distributions within the CpG islands have been classified: Pat A, B, C, D, and E. 21.6% and 10.8% of the Ig genes fall into the Pat B and Pat D groups, respectively, which were significantly higher than the non-Ig genes examined (8.2% and 3.8%). Moreover, the length of CpG islands is shorter in human Ig genes than in non-Ig genes but is much longer than in mouse orthologues. These findings provide a clear picture of non-neutral and nonrandom occurrence of the CpG islands in the PPRs of human and mouse Ig genes, which facilitate rational recommendations regarding their nomenclature. (C) 2005 Elsevier B.V. All rights reserved.

Epithelial transport and deamidation of gliadin peptides:a role for coeliac disease patient immunoglobulin A

In coeliac disease, the intake of dietary gluten induces small-bowel mucosal damage and the production of immunoglobulin (Ig)A class autoantibodies against transglutaminase 2 (TG2). We examined the effect of coeliac patient IgA on the apical-to-basal passage of gluten-derived gliadin peptides p31-43 and p57-68 in intestinal epithelial cells. We demonstrate that coeliac IgA enhances the passage of gliadin peptides, which could be abolished by inhibition of TG2 enzymatic activity. Moreover, we also found that both the apical and the basal cell culture media containing the immunogenic gliadin peptides were able to induce the proliferation of deamidation-dependent coeliac patient-derived T cells even in the absence of exogenous TG2. Our results suggest that coeliac patient IgA could play a role in the transepithelial passage of gliadin peptides, a process during which they might be deamidated.

Plasma antioxidant status, immunoglobulin G oxidation and lipid peroxidation in demented patients:Relevance to Alzheimer disease and vascular dementia

A large body of evidence supports a role of oxidative stress in Alzheimer disease (AD) and in cerebrovascular disease. A vascular component might be critical in the pathophysiology of AD, but there is a substantial lack of data regarding the simultaneous behavior of peripheral antioxidants and biomarkers of oxidative stress in AD and vascular dementia (VaD). Sixty-three AD patients, 23 VaD patients and 55 controls were included in the study. We measured plasma levels of water-soluble (vitamin C and uric acid) and lipophilic (vitamin E, vitamin A, carotenoids including lutein, zeaxanthin, β-cryptoxanthin, lycopene, α- and β-carotene) antioxidant micronutrients as well as levels of biomarkers of lipid peroxidation [malondialdehyde (MDA)] and of protein oxidation [immunoglobulin G (IgG) levels of protein carbonyls and dityrosine] in patients and controls. With the exception of β-carotene, all antioxidants were lower in demented patients as compared to controls. Furthermore, AD patients showed a significantly higher IgG dityrosine content as compared to controls. AD and VaD patients showed similar plasma levels of plasma antioxidants and MDA as well as a similar IgG content of protein carbonyls and dityrosine. We conclude that, independent of its nature - vascular or degenerative - dementia is associated with the depletion of a large spectrum of antioxidant micronutrients and with increased protein oxidative modification. This might be relevant to the pathophysiology of dementing disorders, particularly in light of the recently suggested importance of the vascular component in AD development. Copyright © 2004 S. Karger AG, Basel.

Interactions among secretory immunoglobulin A, CD71, and transglutaminase-2 affect permeability of intestinal epithelial cells to gliadin peptides

BACKGROUND & AIMS: The transferrin receptor (CD71) is up-regulated in duodenal biopsy samples from patients with active celiac disease and promotes retrotransport of secretory immunolglobulin A (SIgA)-gliadin complexes. We studied intestinal epithelial cell lines that overexpress CD71 to determine how interactions between SIgA and CD71 promote transepithelial transport of gliadin peptides. METHODS: We analyzed duodenal biopsy specimens from 8 adults and 1 child with active celiac disease. Caco-2 and HT29-19A epithelial cell lines were transfected with fluorescence-labeled small interfering RNAs against CD71. Interactions among IgA, CD71, and transglutaminase 2 (Tgase2) were analyzed by flow cytometry, immunoprecipitation, and confocal microscopy. Transcytosis of SIgACD71 complexes and intestinal permeability to the gliadin 3H-p3149 peptide were analyzed in polarized monolayers of Caco-2 cells. RESULTS: Using fluorescence resonance energy transfer and in situ proximity ligation assays, we observed physical interactions between SIgA and CD71 or CD71 and Tgase2 at the apical surface of enterocytes in biopsy samples and monolayers of Caco-2 cells. CD71 and Tgase2 were co-precipitated with SIgA, bound to the surface of Caco-2 cells. SIgACD71 complexes were internalized and localized in early endosomes and recycling compartments but not in lysosomes. In the presence of celiac IgA or SIgA against p3149, transport of intact 3H-p3149 increased significantly across Caco-2 monolayers; this transport was inhibited by soluble CD71 or Tgase2 inhibitors. CONCLUSIONS: Upon binding to apical CD71, SIgA (with or without gliadin peptides) enters a recycling pathway and avoids lysosomal degradation; this process allows apicalbasal transcytosis of bound peptides. This mechanism is facilitated by Tgase2 and might be involved in the pathogenesis of celiac disease.

Molecular studies in gorgonian alloimmunity : search for gene homologs of the immunoglobulin gene superfamily in Swiftia exserta

Humoral and cells surface molecules of the mammalian immune system, grouped into the Immunoglobulin Gene Superfamily, share protein structure and gene sequence homologies with molecules found among diverse phylogenetic groups. In histocompatibility studies, the gorgonian coral Swiftia exserta has recently demonstrated specific alloimmunity with memory (Salter-Cid and Bigger, 1991. Biological Bulletin Vol 181). In an attempt to shed light on the origins of this gene family and the evolution of the vertebrate immune response, genomic DNA from Swiftia exserta was isolated, purified, and analyzed by Southern blot hybridization with mouse gene probes corresponding to two molecules of the Immunoglobulin Gene Superfamily, the Thy-1 antigen, and the alpha-3 domain of the MHC Class I histocompatibility marker. Hybridizations were conducted under low to non-stringent conditions to allow binding of mismatched homologs that may exist between the mouse gene probes and the Swiftia DNA. Removal of non-specific binding (sequences less than 70% homologous) occurred in washing steps. Results show that with the probes selected, the method chosen, and the conditions applied, no evidence of sequences of 70% or greater homology to the mouse Thy-1 or MHC Class I alpha-3 genes exist in Swiftia exserta genome.