bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dextran-conjugated anti-IgD antibodies inhibit T cell-mediated IgE production but augment the synthesis of IgM and IgG.
Authors: Peçanha L M , Yamaguchi H , Lees A , Noelle R J , Mond J J , Snapper C M 
Published: December 2022

Abstract
We previously demonstrated that anti-IgD antibodies conjugated to dextran (alpha delta-dex) were a potent co-stimulus for Ig secretion by resting murine B cells in the presence of cytokines. However, although alpha delta-dex stimulated the secretion of most Ig isotypes it selectively failed to costimulate IgE production even in the presence of high concentrations of IL-4. Earlier reports indicated that unconjugated anti-IgM, which was not an effective costimulus for Ig secretion, in fact inhibited Ig production induced by LPS. We determined the effect of alpha delta-dex, at concentrations that costimulated cytokine-induced Ig secretion, on Ig production by LPS- or T cell-activated B cells, and whether IgE production was affected in a selective manner. We observed that alpha delta-dex inhibited Ig isotype production (IgE &gt; IgG &gt; IgM) by LPS-activated B cells, while further stimulating their proliferation. This effect of alpha delta-dex was mediated directly at the level of the B cell and was accompanied by a comparable inhibition in Ig class switching, as assessed by flow cytometric analysis of membrane Ig isotype-positive cells. The inhibitory effects of alpha delta-dex on LPS-induced Ig secretion and class switching occurred at 1000-fold lower concentrations of anti-IgD than that reported necessary for inhibition by unconjugated anti-IgM. Whereas IL-4 + IL-5 costimulated Ig isotype production by alpha delta-dex-activated cells, the further addition of LPS led to a marked ablation of the Ig secretory response indicating the cross-inhibitory effects of these two modes of B cell activation. By contrast, alpha delta-dex augmented IgM and IgG1 secretion by resting B cells stimulated with either an anti-CD3-activated CD4+ Th2 clone or with activated T cell membranes in combination with IL-4 + IL-5. However, alpha delta-dex potently inhibited T cell-mediated IgE secretion. These findings underscore the existence of, and demonstrate a number of novel interrelationships between, three distinct pathways of B cell differentiation induced by different modes of activation. Further, the observation that pg/ml quantities of alpha delta-dex selectively inhibits T cell-induced IgE production in vitro suggests a novel strategy to down-regulate this Ig isotype in vivo.
Induction of costimulatory molecule B7 in M12 B lymphomas by cAMP or MHC-restricted T cell interaction.
Authors: Watts T H , Alaverdi N , Wade W F , Linsley P S 
Published: December 2022

Abstract
M12 B lymphomas expressing transfected Ak molecules with truncated cytoplasmic domains have a defect in Ag presentation to some autoreactive T cell hybrids. This defect in Ag presentation is corrected by pretreatment of the B cells with agents that elevate intracellular cAMP. Here we show that dibutyryl-cAMP treatment of M12 B lymphomas leads to cell surface expression of the costimulatory molecule B7. Furthermore, CTLA4Ig, a ligand for B7, inhibits activation of an accessory signal-dependent T hybrid. B7 is also inducible in M12 B lymphomas upon MHC-restricted interaction with T cells that can be activated by the APC, but not by T cells that fail to respond to truncated MHC-bearing M12 cells. Activation of the unresponsive T hybrids with immobilized anti-CD3 confers on them the ability to induce B7 in the APC. Direct engagement by immobilized antibodies of MHC class II on M12 B lymphomas did not induce B7 expression. Taken together, these results imply that during T-B interaction, initial T cell activation events lead to the ability of the T cell to induce costimulatory activity in the B cell, which in turn further activates the T cell. Activated T cell supernatants induced a small amount of B7 but were not nearly as effective as cAMP or as coincubation of T and B cells. These results suggest a role for T-B contact or localized cytokine secretion in the induction of B7 during T-B interaction.
Stimulation of human T cells by streptococcal "superantigen" erythrogenic toxins (scarlet fever toxins).
Authors: Braun M A , Gerlach D , Hartwig U F , Ozegowski J H , Romagné F , Carrel S , Köhler W , Fleischer B 
Published: December 2022

Abstract
The pyrogenic (erythrogenic) exotoxins A and C (SPEA and SPEC) of Streptococcus pyogenes belong to the family of mitogenic toxins of which the staphylococcal enterotoxins are the prototypes. The erythrogenic toxin B (SPEB) is a proteinase precursor. All SPE have been reported to be superantigens. Here we have analyzed the human T cell response to these toxins. We used highly purified preparations of SPEA, SPEB, and SPEC from different S. pyogenes strains. These toxins were apparently homogenous in SDS-PAGE, IEF, and HPLC. In addition, recombinant SPEA and SPEC were produced in Escherichia coli. In cultures of PBMC, all three toxins expanded preferentially a fraction of T cells. Using mAb against V beta 2, -5, -6, -8, and -12, we investigated the phenotype of the stimulated cells. Natural SPEA, SPEB, and SPEC strongly stimulated V beta 8+ T cells, whereas recombinant SPEA and SPEC did not. Both natural and recombinant SPEA stimulated V beta 12+ cells and both natural and recombinant SPEC stimulated V beta 2+ cells. In accordance with these findings, a human V beta 8+ line responded to all three toxins derived from S. pyogenes but not to the recombinant proteins. An antiserum against natural SPEC neutralized specifically the V beta 2-stimulating activity of SPEC and the V beta 8-stimulating activity of all three toxins, but had no effect on the response to other superantigens. This shows that trace amounts of a potent novel V beta 8-stimulating activity not identical to SPEA and SPEC are responsible for the stimulation of V beta 8+ T cells by natural SPEA and SPEC reported previously. In a preliminary screening of S. pyogenes strains from patients, we found that this novel superantigen appears to be more widely distributed than SPEA and SPEC. Furthermore, we present evidence that also the superantigenic properties of SPEB are due to contaminations with this V beta 8 stimulator. The response to SPEB usually required 1000 times higher concentrations than to SPEA or SPEC. Antisera to SPEC but not to SPEB inhibited the response of PBMC and V beta 8+ Jurkat cells to SPEB. Furthermore, more stringent purification of SPEB yielded SPEB preparations devoid of mitogenic activity. These results indicate that the mitogenicity that is commonly attributed to SPEB is due to minute contaminations of the V beta 8 stimulator. These results raise two important caveats for the work with these highly potent T cell mitogens.(ABSTRACT TRUNCATED AT 400 WORDS)
Comparison of the requirements for cognate T cell help for IgG anti-double-stranded DNA antibody production in vitro: T helper-derived lymphokines replace T cell cloned lines for B cells from NZB.H-2bm12 but not B6.H-2bm12 mice.
Authors: Cawley D , Chiang B L , Naiki M , Ansari A A , Gershwin M E 
Published: December 2022

Abstract
We have isolated, from NZB.H-2bm12 mice, several autoreactive cloned T cell lines that provide help for anti-dsDNA IgG antibody production in vitro. The purpose of the work described herein was to examine the requirement for cognate help for the production of anti-DNA antibodies in vitro. Thus, the ability of cloned T cell lines or lymphokines derived from them to provide help for T-depleted spleen cells from both normal B6.H-2bm12 mice and SLE-prone NZB.H-2bm12 mice was examined. Two autoreactive cloned T cell lines were selected for detailed study. 410F T cells respond to APC from both I-Ab and I-Abm12 mice, whereas 410H T cells are restricted to I-Abm12. By using Percoll gradients, B cells from both low density and high density fractions were cultured with autoreactive cloned T cell lines or lymphokines secreted by such cloned T cell lines, and anti-DNA antibody production was determined. Lymphokines elicited IgM anti-ssDNA antibody production from cells in all Percoll fractions from both B6.H-2bm12 and NZB.H-2bm12 mice. Lymphokines did not elicit production of IgG anti-dsDNA antibody production by cells from 2-month-old B6.H-2bm12 mice. In contrast, substantial production of IgG anti-dsDNA antibody was observed for NZB.H-2bm12 cells in response to lymphokines alone. Thus, B cells from NZB.H-2bm12 mice, because of previous activation in vivo, can proceed to IgG anti-dsDNA antibody production in vitro without direct T cell interaction. When we examined direct T cell help for the IgG anti-dsDNA antibody response, we found that we could distinguish the actions of the two cloned T cell lines studied. 410F T cells provided help predominantly for cells from low density Percoll fractions whether the cells were derived from B6.H-2bm12 or NZB.H-2bm12 mice. 410H T cells were capable of providing help for cells from both the low and high density fractions, and this help accounted for more than half of the antibody production in vitro by cells from B6.H-2bm12 mice.
Promoter of the human NF-kappa B p50/p105 gene. Regulation by NF-kappa B subunits and by c-REL.
Authors: Cogswell P C , Scheinman R I , Baldwin A S 
Published: December 2022

Abstract
NF-kappa B is a transcription factor involved in the regulation of numerous genes encoding proteins involved in immune function, in inflammation or in cellular growth control. NF-kappa B is typically characterized as a heterodimer of a 50-kDa subunit (p50) and a 65-kDa (p65) subunit. Interestingly, the p50 subunit is derived by processing of a 105-kDa precursor. Induction of NF-kappa B DNA-binding activity involves both the release of cytoplasmically stored factor from its inhibitor known as I kappa B and the induction of NF-kappa B gene expression. We report here the cloning and functional analysis of the promoter of the p50/p105 NF-kappa B gene. Our data suggest the existence of multiple transcription initiation sites for this gene in the B cell line Raji, Jurkat T cells, and HeLa cells. The promoter is constitutively active in these cells and is inducible by phorbol ester and mitogen stimulation of Jurkat T cells. Expression of I kappa B inhibits this inducible activation of the p50/p105 promoter. Furthermore, we have shown that co-transfection of a p50/p105 promoter-reporter plasmid with expression vectors encoding the p50 or p65 subunits of NF-kappa B or c-Rel results in stimulation of gene expression. Supportive of the transfection data, we have identified a DNA-binding site for NF-kappa B in the promoter of the p50/p105 gene that is responsive only to a combination of p50 and p65. The data demonstrate that the p50/p105 NF-kappa B gene is regulated by members of the NF-kappa B/Rel family and likely by other important transcription factors.
Transcriptional control of MHC class I and beta 2-microglobulin genes in vivo.
Authors: Drezen J M , Babinet C , Morello D 
Published: December 2022

Abstract
The expression of class I and beta 2-microglobulin (beta 2-m) genes, which encode the H and L chains of the H-2 histocompatibility Ag, respectively, is complex both in the adult mouse and during development. Although they are ubiquitously expressed in the adult, the mRNA levels of these genes are variable from one organ to another, being high in liver, lung, and lymphoid organs and low in brain and testis. During development, both class I and beta 2-m mRNA are poorly expressed. To determine the molecular mechanism, either transcriptional or post-transcriptional, controlling class I and beta 2-m mRNA levels, we have compared their transcriptional activities by performing run-on experiments with nuclei extracted from several embryonic and adult organs. We show that most of the differences observed in H-2 and beta 2-m mRNA steady state levels are the reflection of their different transcriptional activities. These results demonstrate that MHC class I and beta 2-m gene expression in adult organs, as well as during development, is mainly controlled at the transcriptional level.
Chromosomal organization of the human VH4 gene family. Location of individual gene segments.
Authors: van der Maarel S , van Dijk K W , Alexander C M , Sasso E H , Bull A , Milner E C 
Published: December 2022

Abstract
To investigate the organization and evolution of VH gene segments, we characterized the elements belonging to the VH4 gene family from the germline of a single subject. One hundred sixty VH4-carrying lambda-phage clones were isolated from a genomic library. A combination of hybridization and sequence analysis yielded 13 distinct VH4 clones. Six of these elements had one or more nucleotide substitutions that distinguished them from previously identified VH4 genes, whereas seven elements were identical to previously described VH4 genes. In four of the six new sequences, nucleotide substitutions resulted in amino acid replacements. One pseudogene was identified. On the basis of sequence-specific hybridization using oligonucleotide probes corresponding to these sequences, each of the elements could be assigned to a specific band in a BglII digest. Since the VH4-carrying BglII bands have been mapped in genomic DNA, it was also possible to assign chromosomal locations to the specific VH4 elements. The results indicate that the majority of VH4 elements are located in a region of approximately 500 kb, extending from approximately 500 to 1000 kb 5' of the JH locus. The distribution of shared structural motifs among the VH4 elements indicates that the VH4 gene family has evolved through repeated duplication and gene conversion events.
Involvement of CD14 in lipopolysaccharide-induced tumor necrosis factor-alpha, IL-6 and IL-8 release by human monocytes and alveolar macrophages.
Authors: Dentener M A , Bazil V , Von Asmuth E J , Ceska M , Buurman W A 
Published: December 2022

Abstract
CD14 has been reported to function as a receptor for bacterial LPS complexed with serum proteins, transducing an activation signal for TNF-alpha production. We found that the anti-CD14 mAb MEM-18 inhibited not only LPS-induced release of TNF-alpha, but also LPS-induced, TNF-alpha independent release of IL-6 and IL-8 by human monocytes and alveolar macrophages. Inhibitory effect of MEM-18 was detected both in the presence of human or bovine calf serum and under serum-free conditions. In contrast, MEM-18 did not block release of these cytokines induced by IL-1 beta, TNF-alpha, PMA, and zymosan. We conclude that CD14 is involved in LPS-induced release of TNF-alpha, IL-6, and IL-8 by monocytes and alveolar macrophages and that this receptor appears to be able to recognize LPS directly in the absence of serum.
Characterization of T helper cell responses to the trypanosome variant surface glycoprotein.
Authors: Schleifer K W , Filutowicz H , Schopf L R , Mansfield J M 
Published: December 2022

Abstract
T cell responses to the variant surface glycoprotein (VSG) previously have not been detected in animals infected with the African trypanosomes despite the fact that such animals make strong T-dependent B cell responses to VSG molecules displayed by the parasites. In the present study, we have examined B 10.BR mice for VSG-specific Th cell responses at different times after infection with Trypanosoma brucei rhodesiense clone LouTat 1. T cell populations derived from different tissues were tested for their ability to proliferate and secrete cytokines when stimulated with purified LouTat 1 VSG. Furthermore, VSG-specific T cell lines and clones were derived from immunized mice and examined for their phenotypic and functional profiles in comparison with T cell responses of infected mice. The results of this study show that VSG-specific T cells were not consistently detected in the peripheral lymphoid tissues such as spleen or lymph nodes of infected animals. In contrast, VSG Ag-specific T cells were detectable principally in the peritoneal T cell populations of infected mice. Peritoneal T cells did not proliferate in response to VSG, yet produced substantial cytokine responses when stimulated; the cytokines produced were IFN-gamma and IL-2, without detectable IL-4. The cellular phenotype of VSG-responsive T cells was that of classical Th cells in that all cells were CD4-positive and expressed the CD3 alpha/beta TCR membrane complex. Thus, the VSG appears to preferentially stimulate a Th1 cell subset response during infection. Intrinsic molecular characteristics of the VSG molecule did not induce mice to make this response, however, since VSG-specific T cell lines derived from VSG-immunized mice displayed cytokine profiles characteristic of both Th1 and Th2 cells. Isolation of Th1 clones from selected lines demonstrated that these cells displayed the same membrane-phenotypic characteristics and cytokine profiles as the T cells from infected mice. Furthermore, all Th clones were VSG type-specific, APC-dependent, and I-Ak-restricted in their responses. In summary, these experiments provide the first direct evidence for VSG-specific responses at the T cell level. T cell responses to the VSG molecule during infection appear to be anatomically compartmentalized and exhibit evidence of clonal maturation (cytokine production) but not clonal expansion (proliferation) after antigenic stimulation. The cellular phenotype and cytokine profiles predict that infection predisposes the animals to mount Th1 cell subset responses to VSG. The results of this study, including the T clones generated, provide an experimental basis for examining the regulation of VSG-specific immune responses during infection.
Colonial morphotype as a determinant of cytokine expression by human monocytes infected with Mycobacterium avium.
Authors: Shiratsuchi H , Toossi Z , Mettler M A , Ellner J J 
Published: December 2022

Abstract
Mycobacterium avium is an intracellular pathogen that causes disseminated infection in patients with AIDS. Colonial morphotype (smooth-transparent (SmT) vs smooth-domed (SmD)) is a key determinant of virulence in mice and the capacity for replication in human monocytes. Some cytokines (IL-1 and IL-6) promote, whereas others (IFN-gamma and TNF) inhibit intracellular M. avium growth. The specific factors that determine virulence of M. avium, however, are not clear. In this study, we examined cytokine expression by human monocytes stimulated with isogeneic cloned isolates of M. avium. Monocytes were prepared from healthy donors and cultured with or without isogeneic M. avium for up to 7 days. Cytokine levels (IL-1, IL-6, and TNF-alpha) in monocyte supernatants and cell lysates were measured by immunoassay using an ELISA. The expression of cytokine mRNA by monocytes infected with M. avium also was determined by extracting total RNA and subjecting it to Northern blot analysis. Optimal cytokine release occurred at 24 h. SmD induced higher levels of the following cytokines in supernatants than SmT: IL-1 alpha (140 +/- 32 (mean +/- SE) vs 47 +/- 16 pg/ml, p &lt; 0.02), IL-1 beta (4.0 +/- 0.9 vs 1.7 +/- 0.5 ng/ml, p &lt; 0.01), and TNF-alpha (2725 +/- 546 vs 1464 +/- 409 pg/ml, p &lt; 0.01). IL-6 production was comparable for both strains. SmD and SmT isolates induced comparable levels of steady state mRNA for IL-1 beta, TNF, and IL-6. Pulse-chase analysis indicated that differences in cytokine expression between SmT and SmD occurred in monocyte lysates at the earliest time point (immediately after pulse-labeling). The dissociation of the expression of specific mRNA from production of IL-1 and TNF suggests that translational capacity for the expression of certain cytokines was reduced by the more virulent SmT. Differential induction of cytokine may be a factor in the pathogenicity of M. avium strains isolated from patients with AIDS.
The regulation of T cell-dependent antibody formation in vitro by CD40 ligand and IL-2.
Authors: Grabstein K H , Maliszewski C R , Shanebeck K , Sato T A , Spriggs M K , Fanslow W C , Armitage R J 
Published: December 2022

Abstract
Our study demonstrates the central role for the murine CD40 ligand and IL-2 in contact-dependent T cell help for Ag-specific primary antibody responses in vitro. Helper T cell clones were found to express CD40 ligand after activation with CD3 mAb. Membrane-bound recombinant CD40 ligand expressed on fixed CV1/EBNA cells had similar B cell-activating properties as T cell clones that had been activated and then fixed. These activities include the induction of B cell proliferation, induction of polyclonal secretion of multiple Ig isotypes in a cytokine-dependent manner, and induction of Ag-specific antibody responses by purified B cells. The induction of polyclonal Ig secretion by the recombinant CD40 ligand required IL-4 and IL-5 although optimal Ag-specific antibody formation required IL-2. Finally, soluble CD40.Fc inhibited the induction of Ag-specific antibody responses by fixed, activated Th cell clones. The requirement for both CD40 ligand and IL-2 for induction of Ag-specific antibody responses was mediated, in part, by the induction of B cell IL-2R expression by CD40 ligand. We conclude that the interaction of CD40 on B cells with its ligand on activated T cells is an integral event in the early activation of B cells to grow and differentiate to antibody formation.
Costimulation of peripheral blood T cell activation by human endothelial cells. Enhanced IL-2 transcription correlates with increased c-fos synthesis and increased Fos content of AP-1.
Authors: Hughes C C , Pober J S 
Published: December 2022

Abstract
Endothelial cells (EC) act as APC for resting PBL in vitro, and may have important roles in vivo in the pathogenesis of allograft rejection and delayed hypersensitivity. We previously reported that human umbilical vein EC provide costimulatory signals to PHA-stimulated PBL via CD2:lymphocyte function-associated Ag-3 and an unidentified ligand pair, resulting in a three- to eight-fold enhancement of IL-2 production. The physiologic relevance of this increase was demonstrated by the proliferative advantage provided by EC to PBL suboptimally stimulated with mAb OKT3. We now report that EC costimulation causes increased levels of IL-2 mRNA as a result of increased IL-2 transcription in PBL. We therefore examined the effects of EC on T cell nuclear factors known to regulate IL-2 transcription, including c-jun and c-fos-two components of the transcription factor AP-1, NFAT, and others. PBL constitutively express c-jun transcripts, and the level of c-jun mRNA is not altered by PHA activation in the absence or presence of EC. In contrast, c-fos mRNA is absent from resting T cells and is induced on PHA activation. EC alone do not induce c-fos mRNA but augment the level of c-fos mRNA in PHA-activated T cells by 3- to 10-fold. This effect is largely independent of the CD2:lymphocyte function-associated Ag-3 pathway. Gel-shift analysis reveals the constitutive presence of nuclear factors in resting PBL that bind to the proximal AP-1 site of the IL-2 promoter and that contain immunoreactive c-Jun but not c-Fos protein. In contrast, AP-1 from PHA-activated cells contains c-Jun and low levels of c-Fos. Strikingly, costimulation with EC results in a dramatic increase (up to 15-fold) in the c-Fos content of AP-1. Levels of other nuclear factors involved in IL-2 regulation were not altered by EC, although NFAT-DNA complexes migrated at a slightly different mobility. In summary, our data suggest that changes in the composition of transcription factor AP-1 is a key molecular mechanism for increasing IL-2 transcription and may underlie the phenomenon of costimulation by EC.