bluuebunny/crossref_metadata_2025_split huggingface dataset:
Repertoire diversity of antibody response to bacterial antigens in aged mice. III. Phosphorylcholine antibody from young and aged mice differ in structure and protective activity against infection with Streptococcus pneumoniae.
Authors: Nicoletti C , Yang X , Cerny J 
Published: December 2022

Abstract
Aging in mice is accompanied by qualitative changes in the antibody repertoire to phosphorylcholine (PC), a natural epitope of certain pneumococci. The PC-specific mAb from young/adult (2-4 mo) BALB/c mice are uniformly encoded by the canonical IgV genes of T15 family, whereas the antibody from aged mice (&gt; or = 20 mo) are molecularly heterogeneous, being encoded by various VH and VL genes of non-T15 families. Interestingly the young/adult and aged BALB/c mice produce comparable amounts of antibodies to PC regardless of the molecular shift in the antibody repertoire. This finding prompted our study on the relative ability of PC antibodies from young and aged donors to protect mice against virulent infection with type 3 pneumococci. Passive administration (i.p.) of pooled, PC-specific mAb generated from young donors (all from the T15 Ig gene family) protected the recipients against subsequent i.p. challenge with a lethal dose of Streptococcus pneumoniae strain WU2, in a dose-dependent manner. In contrast, a mixture of PC mAb from aged donors (all from non-T15 families) failed to protect the mice against the infection, even at the highest amount of administered (100 micrograms of mAb/recipient). Average affinity of the aged mAb for the free hapten (PC-chloride) as well as their binding to the bacteria was lower than that of the young mAb. Similarly, affinity-purified serum PC antibody from S. pneumoniae vaccine-immunized young mice afforded a measurable degree of passive protection against the pneumococcal infection whereas a similar dose of serum PC antibody from aged mice did not. Further experiments showed that PC mAb from young donors were equally protective in either young or aged recipients challenged with the bacteria. These results demonstrate that the aged immune system may, in some instances, produce high levels of antibody that are structurally different and less protective against microbial infection.
Mobilization of different arachidonate pools and their roles in the generation of leukotrienes and free arachidonic acid during immunologic activation of mast cells.
Authors: Fonteh A N , Chilton F H 
Published: December 2022

Abstract
Immunologic activation of mast cells leads to the mobilization of arachidonic acid (AA) from membrane phospholipids and the subsequent conversion of this AA to bioactive products. The objective of our study was to determine if segregated pools of AA-containing phospholipids within mast cells serve as independent sources of AA. Initial studies indicated that the appearance of free AA occurred rapidly (maximal level formed within 1 min) within supernatant fluids of Ag-stimulated mast cells and was kinetically different from the formation of leukotriene (LT) B4 or LTC4. To examine whether free AA and leukotrienes were mobilized from different sources, AA-containing phospholipids of mast cells were labeled with [14C] and [3H] AA such that all major subclasses (1-acyl-1-alkyl-1-alk-1'-enyl) of phospholipids contained different ratios of [3H] to [14C] (sp. act. ratios (SAR)). Mast cells were then stimulated with Ag and the SAR of cellular AA, extracellular AA and extracellular LTC4, LTB4, 6-trans LTB4, were determined. The SAR were uniform in all LT and mimicked the ratio found in cellular AA. By contrast, the SAR of AA released into supernatant fluids was twofold lower than that of LT. This indicated that AA released as free fatty acid clearly was derived from a different lipid pool than AA that formed LT. Although it was apparent that the pools which gave rise to AA and LT were different, defining phospholipid(s) that constitute these distinct pools proved more difficult. The SAR of LT suggested that their cellular precursor AA could have been derived from several phospholipid subclasses; however, the SAR in phosphatidylcholine and phosphatidylinositol most closely matched the LT. The SAR of AA in supernatant fluids implied that it was derived, in part, from phosphatidylethanolamine subclasses. Taken together, these data suggest that there are at least two different pools of AA that are mobilized in mast cells during Ag activation.
Regulation of HIV-1 expression by cytokine networks in a CD4+ model of chronic infection.
Authors: Butera S T , Roberts B D , Folks T M 
Published: December 2022

Abstract
Using the CD4+ model of chronic HIV-1 infection, OM-10.1, we investigated the influence of TNF-alpha regulatory networks on induced viral expression. Previously, OM-10.1 cultures were characterized to respond to exogenous TNF-alpha, as nearly 100% of the cells were activated to express HIV-1 within 24 h. In this study, OM-10.1 cells were pulse-treated, by applying exogenous factors for short periods of time and then washing, to determine if autocrine TNF-alpha could sustain HIV-1 activation in the absence of additional exogenous stimulation. After a TNF-alpha pulse treatment, the progressive increase of HIV-1-expressing OM-10.1 cells was prevented by the continuous presence of anti-TNF-alpha mAb. The inductive activity of supernatant from TNF-alpha pulse-treated OM-10.1 cultures was completely removed by absorption on immobilized anti-TNF-alpha mAb. In addition, TNF-alpha pulse-treated OM-10.1 cells activated HIV-1 expression in untreated OM-10.1 cells when cultured across a permeable membrane indicating paracrine effects. Interestingly, if TNF-alpha pulse-treated OM-10.1 cells were further pulse-treated with anti-TNF-alpha mAb, a marked reduction in autocrine TNF-alpha was observed although the level of newly synthesized TNF-alpha mRNA remained unaffected. A similar degree of inhibition over autocrine TNF-alpha production was observed when soluble TNF receptors were used as the second pulse treatment in these experiments. Although the applicability of these results to in vivo chronically HIV-1-infected cells remains to be realized, these results do indicate that activated HIV-1 expression can be influenced by self-perpetuating mechanisms during periods of limited exogenous stimulation. Furthermore, physiologic mechanisms involving soluble cytokine receptors that counteract autocrine and paracrine activation of HIV-1 expression are shown here to play a regulatory role.
Repertoire of neutralizing human monoclonal antibodies specific for the V3 domain of HIV-1 gp120.
Authors: Gorny M K , Xu J Y , Karwowska S , Buchbinder A , Zolla-Pazner S 
Published: December 2022

Abstract
HIV infection induces antibodies that mediate neutralization of cell-free virus and may protect against viral infection. Neutralizing human mAb that bind to the third hypervariable domain (V3) of gp120 have been generated from PBL of HIV-seropositive subjects. Twelve such mAb recognize 9 different epitopes spanning an 11 amino acid stretch at the tip of the V3MN loop. The epitopes of an additional two mAb have not been precisely determined but occur within a 15-mer peptide around the tip of the V3 loop. Eleven of 13 mAb are reactive with at least one other V3 peptide besides MN, indicating that cross-reactivity is a common phenomenon amongst anti-V3 antibodies. All the mAb achieved 50% neutralization of HIVMN at antibody concentrations of 12 to 4700 ng/ml. Two mAb, which recognized epitopes at the top of the V3 loop, GPGR and GRAF, neutralized strains as divergent as MN and IIIB. The affinities of all mAb tested were shown to be substantially higher for the rgp120 than for a 23-mer peptide from the V3 loop of the homologous strain. A significant inverse correlation was demonstrated between affinities and the 50% neutralizing doses for HIVMN.
Studies of T cell deletion and T cell anergy following in vivo administration of SEB to normal and lupus-prone mice.
Authors: Scott D E , Kisch W J , Steinberg A D 
Published: December 2022

Abstract
This study examines the responses of lupus-prone NZB, (NZB x NZW) F1, BXSB, MRL-lpr/lpr and control mice (H-2 and Mls matched) to in vivo administration of the superantigen staphylococcal enterotoxin B (SEB). Two weeks after i.v. administration of 500 micrograms SEB, CD4+V beta 8+ lymph node T cells were deleted equivalently by lupus-prone and control mice. However, IE+ strains deleted a greater proportion (47% to 77%) of their CD4+V beta 8+ cells than did IE- strains (24% to 27%). CD8+V beta 8+ cells were deleted less than CD4+V beta 8+ cells by injection of 500 micrograms SEB. IE- strains failed to delete CD8+V beta 8+ cells, whereas six of seven IE+ strains deleted &gt; 25% of their CD8+V beta 8+ cells. IE+ MRL-lpr/lpr mice showed some impairment in deletion: they failed to delete CD8+V beta 8+ cells at all doses of SEB and had reduced deletion of CD4+V beta 8+ cells at low doses of in vivo SEB (10 and 50 micrograms). Peripheral expansion of the intrathymically deleted V beta 7 TCR family was not observed in lupus-prone mice 2 wk after 500 micrograms in vivo SEB. In vitro restimulation with SEB of mice previously injected with 500 micrograms SEB demonstrated anergy in T cells from all strains, including the IE- and MRL-lpr/lpr. This result contrasts with previous reports of tolerance defects in lupus-prone strains using B cell read-out assays as measures of tolerance. The present study demonstrates that there is no global defect in peripheral T cell deletion or anergy in lupus-prone mice to the superantigen SEB. Although additional Ag would need to be studied, these experiments raise the possibility that some reported tolerance defects in lupus-prone strains may reflect excessive B cell responses to relatively normal T cell signals.
Activation of alveolar macrophages in asymptomatic HIV-infected individuals.
Authors: Buhl R , Jaffe H A , Holroyd K J , Borok Z , Roum J H , Mastrangeli A , Wells F B , Kirby M , Saltini C , Crystal R G 
Published: December 2022

Abstract
After the initial infection with HIV, there is evidence of immune dysfunction despite an apparent normal clinical state. In the context that the lung is a major site affected by opportunistic infection during the progression of this immune dysfunction, and that some components of the immune system are activated during early HIV infection, we hypothesized that there may be activation of alveolar macrophages (AM), a key component of the pulmonary host defense system, during the asymptomatic phase of HIV infection. Compared to normals, in HIV-infected individuals the class II MHC molecules DR, DQ, and DP were all expressed more frequently and in greater cell surface density on AM (p &lt; 0.03, all comparisons), and there was increased spontaneous release of superoxide anion (O2-.) by AM (p &lt; 0.002). To gain insight into whether the activation of the AM was an inherent property of the cells or dependent on the in vivo milieu, AM were evaluated after 24 h in culture for O2-. release. In contrast to the findings in fresh AM, after 24 h in culture, O2-. release by HIV AM was not different from normals (p &gt; 0.7), suggesting that these AM had been activated in vivo. To assess whether IFN-gamma could be mediating these effects, mRNA levels of the IP-10 gene (a gene specifically induced by increased concentrations of IFN-gamma) were quantified in AM. Strikingly, the IP-10 gene was expressed only in AM of HIV-seropositive individuals, suggesting the AM had been exposed to IFN-gamma in vivo. Overall, these observations are consistent with the concept that the HIV-seropositive state is associated with activation of AM, in part due to local exposure to IFN-gamma.
Identification of multiple T cell epitopes on Bet v I, the major birch pollen allergen, using specific T cell clones and overlapping peptides.
Authors: Ebner C , Szépfalusi Z , Ferreira F , Jilek A , Valenta R , Parronchi P , Maggi E , Romagnani S , Scheiner O , Kraft D 
Published: December 2022

Abstract
Eleven T cell clones (TCC) with specificity for Bet v I were established from the peripheral blood of six birch pollen allergic donors. Bet v I is the major allergen of birch (Betula verrucosa) pollen and shows high homology to the major allergens of pollens of other trees within the order fagales (hazel, alder, hornbeam, oak, etc.), which represent important inhalant allergens in the northern hemisphere. The TCC were shown to react with purified natural, as well as with purified recombinant Bet v I. All clones showed the helper cell phenotype (CD3+CD4+) and expressed the TCR-alpha/beta. The cytokine production pattern in response to stimulation with allergen resulted in enhanced production of IL-4 in 9 of 11 clones. The clones were used for T cell epitope mapping on the Bet v I molecule. For this purpose, peptides with a length of 12 amino acids each and overlapping for 10 residues were synthesized following the amino acid sequence of Bet v I. These 75 peptides were used to stimulate Bet v I-specific T cell clones. Our experiments revealed 7 distinct T cell epitopes on the Bet v I molecule. The epitopes were scattered over the whole molecule, 2 sequences were in agreement with an algorithm previously described for the prediction of T cell epitopes. In 3 cases, we could identify distinct TCC specificities within single individuals. Furthermore, for each donor, none of the peptides representing epitopes for TCC inhibited the binding of IgE antibodies to Bet v I. These results suggest that T cells and IgE antibodies from the same individual recognize different structures on the Bet v I allergen.
The fate of anergic T cells in vivo.
Authors: Migita K , Ochi A 
Published: December 2022

Abstract
The kinetics of Staphylococcal enterotoxin B-(SEB) induced peripheral tolerance has been investigated. Ten days after SEB injection, thymectomized BALB/cByJ mice showed suppressed spleen cell proliferative responses to SEB. After 2 mo the SEB-specific response was partly recovered. Four months later the response of spleen cells of SEB-primed mice was comparable to those of control mice. The proportion of CD4+, V beta 8+ T cells was diminished in the tolerized mice and was not restored even after the response was recovered. Purified CD4+, V beta 8+ T cells from SEB-primed mice after 4 mo responded similarly to SEB as control CD4+, V beta 8+ T cells. These expressed a similar profile of surface markers compared with that of unprimed control cells, except a homing receptor was slightly lower. An experiment that addressed the possibility that non-anergic T cells expand over time and are in fact responsible for the recovery of the proliferative response showed that such events unlikely occur in vivo. Therefore, the data indicate that T cell anergy is reversible in vivo. It is also suggested that the challenge with superantigen results in neither clonal expansion nor specific CD4+, V beta 8+ T cell memory.
Inducible T cell antigen 4-1BB. Analysis of expression and function.
Authors: Pollok K E , Kim Y J , Zhou Z , Hurtado J , Kim K K , Pickard R T , Kwon B S 
Published: December 2022

Abstract
4-1BB is an inducible receptor-like protein expressed in both cytolytic and Th cells. Optimal induction of 4-1BB mRNA in T cells required both PMA and ionomycin stimulation, indicating that protein kinase C activation and increases in intracellular Ca2+ were required for its expression. 4-1BB was categorized as an early activation gene since the protein synthesis inhibitor, cycloheximide, blocked the induction of 4-1BB mRNA. A rat mAb, 53A2, was generated against recombinant soluble 4-1BB and was used to characterize this molecule. 4-1BB is a 30-kDa glycoprotein and appears to exist as both a monomer and a 55-kDa dimer on the cell surface of a T cell clone. The 4-1BB protein may be post-translationally modified since its predicted backbone is 25 kDa. FACS analysis indicated that 4-1BB was inducible and expressed on the cell surface of activated splenic T cells and thymocytes. Cross-linking of 4-1BB on anti-CD3-stimulated T cells with 53A2 resulted in a dramatic enhancement of T cell proliferation. This suggests that 4-1BB may function as an accessory signaling molecule during T cell activation.
Lack of promiscuity in autoantigen-specific H and L chain combinations as revealed by human H and L chain "roulette".
Authors: Portolano S , Chazenbalk G D , Hutchison J S , McLachlan S M , Rapoport B 
Published: December 2022

Abstract
Individual H or L chains from a human autoantibody were used to search for other L or H chains that could form antigen-binding fragments, Fab, with the same specificity. The parent Fab (SP1.2) exhibits high affinity binding for thyroid peroxidase (TPO), a 107-kDa protein that is the major autoantigen in human autoimmune thyroiditis. This autoantibody "roulette," performed by using Ig H and L chain gene libraries expressed in bacteria, increased the frequency of TPO-binding clones in the new libraries. However, the frequency was still much lower than would be the case if promiscuous combinations with a variety of H or L chains were compatible with specific Ag binding. Nucleotide sequence analysis of the H and L chains of the new TPO-binding clones revealed even more restriction. Thus, with the SP1.2 H chain, all 11 new Fab utilized L chains from the same V kappa 1 family germline gene as SP1.2 itself. Similarly, five of six H chains "captured" by the SP1.2 L chain were very closely related to the SP1.2 H chain. However, one totally different H chain was isolated: SP4.6 has a VH region that differs substantially from that of SP1.2. SP4.6 also has a distinct D region, uses a different JH, and, unlike SP1.2, which is an IgG1, belongs to subclass IgG4. The affinities for TPO of SP4.6 (with the different H chain) and SP1.20 (which had the least mutated L chain germline gene) were similar to that of SP1.2 (approximately 10(-10) M). As expected, the SP1.2 and SP1.20 Fab, which have the same H chain and closely related L chains, bound to the same domain on TPO. However, a similar domain on TPO was recognized by both SP4.6 and SP1.2, despite the fact that their V, D, and J regions are quite different. This observation raises the possibility that the L chain is critical in defining epitope specificity, even in the presence of completely different D regions and nonidentical VH regions.
Schistosoma mansoni 28-kDa glutathione S-transferase and immunity against parasite fecundity and egg viability. Role of the amino- and carboxyl-terminal domains.
Authors: Xu C B , Verwaerde C , Gras-Masse H , Fontaine J , Bossus M , Trottein F , Wolowczuk I , Tartar A , Capron A 
Published: December 2022

Abstract
We have previously shown that a mAb that inhibits the enzymatic activity of the Schistosoma mansoni 28-kDa glutathione S-transferase (Sm28 GST) also reduces female worm fecundity and egg viability in vivo and in vitro. By peptidic epitope mapping and an activity reconstitution assay, the carboxyl terminus (CT) amino acid residues 190-211 and to a lesser extent the truncated amino terminus (NT) residues 10-43 of the enzyme were identified as mAb recognition sites. Sera from rats immunized with the NT (10-43) and CT (190-211) peptides showed a partial inhibitory effect on Sm28 GST activity in a late phase (6 to 7 wk) but not in an early phase (2 to 4 wk) after immunization. Passive transfer of Sm28 GST-inhibiting anti-N- and C-terminal sera, but not of the noninhibitory sera, protected the infected mice by reducing tissue egg deposition and the ability of eggs to hatch. In active immunization experiments, the CT peptide significantly decreased the worm burden (37 to 40%) in mice as did the rSm28 GST (28 to 52%). In terms of tissue egg deposition and egg-hatching ability, immunization with both the NT and CT peptides reproduced the reduction observed after immunization with rSm28 GST. A constant reduction in egg numbers was noted in the small intestines and the livers of the immunized mice. A clear reduction in the ability of intestinal or hepatic eggs to hatch was observed. The results are discussed in terms of the conformational participation of the NT and CT of Sm28 in the expression of GST activity.
A novel cytokine-responsive cell surface glycoprotein defines a subset of medullary thymic epithelium in situ.
Authors: Farr A , Nelson A , Hosier S , Kim A 
Published: December 2022

Abstract
A hamster mAb (10.1.1), raised against long term cultures of uncloned thymic stromal cells, selectively labeled a subpopulation of medullary stromal cells in situ. By ultrastructural and phenotypic criteria, the stromal cells labeled by this mAb were judged to be epithelial. Although some of the 10.1.1+ epithelial cells were reticular, others were globular and some were associated with structures resembling Hassal's bodies. Ultrastructural immunohistochemistry suggested that 10.1.1 labeling of some of the epithelial cells was preferentially associated at areas of epithelial cell contact with adjacent thymocytes. Reactivity of thymic stromal cells with this antibody was developmentally regulated. A few scattered 10.1.1+ cells were observed at day 14 of gestation, and there were progressive increases in both the extent and intensity of 10.1.1 labeling evident through birth. One thymic stromal cell line, Z210.1, exhibited low levels of constitutive reactivity with this antibody. Exposure to IL-1 resulted in enhanced 10.1.1 reactivity of this cell line, with little, if any, additional response to TNF-alpha or IFN-gamma. Under the same conditions, ICAM-1 expression by this cell line was elevated in response to IL-1, TNF-alpha, or INF-gamma. Immunoprecipitation of detergent lysates prepared from Z210.1.7 cells exposed to IL-1 24 h before cell surface iodination identified a cell surface protein with a molecular mass of about 92 kDa under nonreducing conditions and about 95 kDa under reducing conditions. Digestion of 10.1.1 immunoprecipitates with N-glyconase resulted in a small (5 kDa) reduction in molecular mass. The molecule recognized by the 10.1.1 mAb was distinct from ICAM-1, which possessed a molecular mass of 100 kDa (nonreduced) and 110 kDa (reduced), and also displayed a smaller N-glyconase-resistant molecular mass (65 to 85 kDa).