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  • The American Association of Immunologists  (7)
  • 1
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 189, No. 10 ( 2012-11-15), p. 4816-4824
    Abstract: Challenge studies following passive immunization with neutralizing Abs suggest that an HIV vaccine could be efficacious were it able to elicit broadly neutralizing Abs (bNAbs). To better understand the requirements for activation of B cells producing bNAbs, we generated cell lines expressing bNAbs or their germline-reverted versions (gl-bNAbs) as BCRs. We then tested the abilities of the bNAb-expressing cells to recognize HIV pseudovirions and vaccine candidate proteins by binding and activation assays. The results suggest that HIV envelope (Env) Ag-expressing, infection-competent virions are poorly recognized by high-affinity bNAb-expressing cells, as measured by the inability of Ags to induce rapid increases in intracellular calcium levels. Other Ag forms appear to be highly stimulatory, in particular, soluble gp140 trimers and a multimerized, scaffolded epitope protein. Virions failed to efficiently activate bNAb-expressing B cells owing to delayed or inefficient BCR recognition, most likely caused by the low density of Env spikes. Importantly, B cells carrying gl-bNAb BCRs were not stimulated by any of the tested vaccine candidates. These data provide insight into why many HIV immunogens, as well as natural HIV infections, fail to rapidly stimulate bNAb responses and suggest that bNAb-expressing cell lines might be useful tools in evaluation of vaccine Ags for infectious diseases. Because soluble Env trimers or multimerized scaffolded epitopes are best at activating B cell-expressing bNAbs, these antigenic forms should be considered as preferred vaccine components, although they should be modified to better target naive gl-bNAb B cells.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2012
    detail.hit.zdb_id: 1475085-5
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  • 2
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 191, No. 6 ( 2013-09-15), p. 3179-3185
    Abstract: Broadly neutralizing Abs against HIV protect from infection, but their routine elicitation by vaccination has not been achieved. To generate small animal models to test vaccine candidates, we have generated targeted transgenic (“knock-in”) mice expressing, in the physiological Ig H and L chain loci, two well-studied broadly neutralizing Abs: 4E10, which interacts with the membrane proximal external region of gp41, and b12, which binds to the CD4 binding site on gp120. 4E10HL mice are described in the companion article (Doyle-Cooper et al., J. Immunol. 191: 3186–3191). In this article, we describe b12 mice. B cells in b12HL mice, in contrast to the case in 4E10 mice, were abundant and essentially monoclonal, retaining the b12 specificity. In cell culture, b12HL B cells responded avidly to HIV envelope gp140 trimers and to BCR ligands. Upon transfer to wild-type recipients, b12HL B cells responded robustly to vaccination with gp140 trimers. Vaccinated b12H mice, although generating abundant precursors and Abs with affinity for Env, were unable to rapidly generate neutralizing Abs, highlighting the importance of developing Ag forms that better focus responses to neutralizing epitopes. The b12HL and b12H mice should be useful in optimizing HIV vaccine candidates to elicit a neutralizing response while avoiding nonprotective specificities.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2013
    detail.hit.zdb_id: 1475085-5
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  • 3
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 191, No. 6 ( 2013-09-15), p. 3186-3191
    Abstract: A major goal of HIV research is to develop vaccines reproducibly eliciting broadly neutralizing Abs (bNAbs); however, this has proved to be challenging. One suggested explanation for this difficulty is that epitopes seen by bNAbs mimic self, leading to immune tolerance. We generated knock-in mice expressing bNAb 4E10, which recognizes the membrane proximal external region of gp41. Unlike b12 knock-in mice, described in the companion article (Ota et al. 2013. J. Immunol. 191: 3179–3185), 4E10HL mice were found to undergo profound negative selection of B cells, indicating that 4E10 is, to a physiologically significant extent, autoreactive. Negative selection occurred by various mechanisms, including receptor editing, clonal deletion, and receptor downregulation. Despite significant deletion, small amounts of IgM and IgG anti-gp41 were found in the sera of 4E10HL mice. On a Rag1−/− background, 4E10HL mice had virtually no serum Ig of any kind. These results are consistent with a model in which B cells with 4E10 specificity are counterselected, raising the question of how 4E10 was generated in the patient from whom it was isolated. This represents the second example of a membrane proximal external region–directed bNAb that is apparently autoreactive in a physiological setting. The relative conservation in HIV of the 4E10 epitope might reflect the fact that it is under less intense immunological selection as a result of B cell self-tolerance. The safety and desirability of targeting this epitope by a vaccine is discussed in light of the newly described bNAb 10E8.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2013
    detail.hit.zdb_id: 1475085-5
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  • 4
    Online Resource
    Online Resource
    The American Association of Immunologists ; 1999
    In:  The Journal of Immunology Vol. 163, No. 12 ( 1999-12-15), p. 6371-6377
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 163, No. 12 ( 1999-12-15), p. 6371-6377
    Abstract: To explore the phylogenetic history of the murine paired Ig-like receptors of activating (PIR-A) and inhibitory (PIR-B) types, we isolated PIR homologues from a rat splenocyte cDNA library. The rat (ra) PIR-A and raPIR-B cDNA sequences predict transmembrane proteins with six highly conserved extracellular Ig-like domains and distinctive membrane proximal, transmembrane, and cytoplasmic regions. The raPIR-B cytoplasmic region contains prototypic inhibitory motifs, whereas raPIR-A features a charged transmembrane region and a short cytoplasmic tail. Southern blot analysis predicts the presence of multiple Pira genes and a single Pirb gene in the rat genome. Although raPIR-A and raPIR-B are coordinately expressed by myeloid cells, analysis of mRNA detected unpaired expression of raPIR-A by B cells and raPIR-B by NK cells. Collectively, these findings indicate that the structural hallmarks of the Pir gene family are conserved in rats and mice, yet suggest divergence of PIR regulatory elements during rodent speciation.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1999
    detail.hit.zdb_id: 1475085-5
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  • 5
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 162, No. 6 ( 1999-03-15), p. 3336-3341
    Abstract: Usually we rely on vaccination to promote an immune response to a pathogenic microbe. In this study, we demonstrate a suppressive form of vaccination, with DNA encoding a minigene for residues 139–151 of myelin proteolipid protein (PLP139–151), a pathogenic self-Ag. This suppressive vaccination attenuates a prototypic autoimmune disease, experimental autoimmune encephalomyelitis, which presents clinically with paralysis. Proliferative responses and production of the Th1 cytokines, IL-2 and IFN-γ, were reduced in T cells responsive to PLP139–151. In the brains of mice that were successfully vaccinated, mRNA for IL-2, IL-15, and IFN-γ were reduced. A mechanism underlying the reduction in severity and incidence of paralytic autoimmune disease and the reduction in Th1 cytokines involves altered costimulation of T cells; loading of APCs with DNA encoding PLP139–151 reduced the capacity of a T cell line reactive to PLP139–151 to proliferate even in the presence of exogenous CD28 costimulation. DNA immunization with the myelin minigene for PLP-altered expression of B7.1 (CD80), and B7.2 (CD86) on APCs in the spleen. Suppressive immunization against self-Ags encoded by DNA may be exploited to treat autoimmune diseases.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1999
    detail.hit.zdb_id: 1475085-5
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  • 6
    Online Resource
    Online Resource
    The American Association of Immunologists ; 2023
    In:  The Journal of Immunology Vol. 210, No. 1_Supplement ( 2023-05-01), p. 219.15-219.15
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 210, No. 1_Supplement ( 2023-05-01), p. 219.15-219.15
    Abstract: The thymus is the primary site of T cell development, generating a diverse repertoire of T cells that protects us from various threats. Despite its crucial role in T cell immunity, the thymus undergoes chronic involution that leads to a decline in T cell production and impaired T cell immunity. Although the thymus is highly sensitive to various forms of damage, and everyday insults like stress and infection, it also has a remarkable capacity to regenerate itself. Though this reparative capacity declines with age. We hypothesized that age-related thymic decline may be attributed to repeated damage and regeneration cycles in response to everyday insults. We expected impaired regeneration with each round of damage. However, we found that after three rounds of damage and repair cycles, overall thymic cellularity consistently returned to homeostasis. Moreover, we also found that unlike injury from ionizing radiation, Dexamethasone (Dex) mediated damage led to thymic hypertrophy. Preliminary studies revealed that type 2 cytokines, previously implicated to promote thymic regeneration, are elevated in the early phases of Dex induced damage, but not during irradiation. Comparing thymic cellularity between damage models, we found that Dex induced damage had faster recovery kinetics and led to thymic hypertrophy 28 days after damage. We hypothesize that type 2 immunity may be a key contributor to hypertrophic thymic regeneration in Dex induced thymic damage. We will test our hypothesis through genetic mouse models, cytokine modulation, and standard immunophenotyping. The positive results of this study will augment our basic knowledge of the endogenous mechanisms of thymic regeneration and inform the creation of thymic boosting therapies. I am supported in part by PHS NRSA T32GM007270 from NIGMS.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 2023
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  • 7
    In: The Journal of Immunology, The American Association of Immunologists, Vol. 161, No. 2 ( 1998-07-15), p. 1034-1044
    Abstract: Vaccination with synthetic TCR peptides from the BV5S2 complementarity-determining region 2 (CDR2) can boost significantly the frequency of circulating CD4+ peptide-specific Th2 cells in multiple sclerosis (MS) patients, with an associated decrease in the frequency of myelin basic protein (MBP)-reactive Th1 cells and possible clinical benefit. To evaluate the immunogenicity of CDR2 vs other regions of the TCR, we vaccinated seven MS patients with overlapping BV5S2 peptides spanning amino acids 1–94. Six patients responded to at least one of three overlapping or substituted CDR2 peptides possessing a core epitope of residues 44–52, and one patient also responded to a CDR1 peptide. Of the CDR2 peptides, the substituted (Y49T)BV5S2-38–58 peptide was the most immunogenic but cross-reacted with the native sequence and had the strongest binding affinity for MS-associated HLA-DR2 alleles, suggesting that position 49 is an MHC rather than a TCR contact residue. Two MS patients who did not respond to BV5S2 peptides were immunized successfully with CDR2 peptides from different BV gene families overexpressed by their MBP-specific T cells. Taken together, these results suggest that a widely active vaccine for MS might well involve a limited set of slightly modified CDR2 peptides from BV genes involved in T cell recognition of MBP.
    Type of Medium: Online Resource
    ISSN: 0022-1767 , 1550-6606
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    Language: English
    Publisher: The American Association of Immunologists
    Publication Date: 1998
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