bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential effect of CTLA4Ig on murine graft-versus-host disease (GVHD) development: CTLA4Ig prevents both acute and chronic GVHD development but reverses only chronic GVHD.
Authors: Via C S , Rus V , Nguyen P , Linsley P , Gause W C 
Published: December 2022

Abstract
The role of costimulation was examined in an in vivo model of alloantigen-driven Th1 or Th2 cytokine responses, the parent-into-F1 model of acute or chronic graft-vs-host disease (GVHD), respectively. The soluble fusion protein, murine CTLA4Ig, which blocks engagement of CD28 by its natural ligand B7-1 and B7-2, was administered either early, at the time of GVHD induction, or delayed, after the establishment of Th1 or Th2 effector responses (day 7). Early administration of CTLA4Ig prevented the development of both acute and chronic GVHD by preventing the activation of donor T cells, i.e., by blocking characteristic Th1 or Th2 cytokine production and blocking memory marker up-regulation on donor T cells. Delayed CTLA4Ig administration was unable to alter acute GVHD but did reverse chronic GVHD as evidenced by normalization of serum autoantibody levels, normal host B cell numbers and MHC class II expression, reduced donor T cell expression of CD40 ligand, and reduced numbers of donor CD4+ memory T cells. The percentage of donor memory cells was not altered by delayed CTLA4Ig. We conclude that in this model, alloantigen-driven Th1 or Th2 responses are equally susceptible to costimulatory blockade at the onset of disease; however, once effector mechanisms become established, only Th2-driven responses have a requirement for further costimulation for the continued expansion of CD4+ T cells. These data suggest that humoral, lupus-like autoimmunity requires continuous T cell help for B cells, and agents that interrupt this process may be beneficial.
Dysregulated intrathymic development in the IL-2-deficient mouse leads to colitis-inducing thymocytes.
Authors: Lúdvíksson B R , Gray B , Strober W , Ehrhardt R O 
Published: December 2022

Abstract
Gene-targeted mice lacking the IL-2 gene (IL-2 -/- mice) develop various forms of autoimmunity as well as severe colitis, either spontaneously in a conventional environment or after immunization with 2,4,6-trinitrophenol (TNP)-conjugated keyhole limpet hemocyanin (KLH) in a specific pathogen-free environment. We show here that the induction of colitis with TNP-KLH induces a change in the thymocyte population characterized by decreased numbers of double positive (DP; CD4+CD8+) thymocytes (IL-2 +/+, 45.2 x 10(6) vs IL-2 -/-, 23.6 x 10(6)) and increased numbers of single positive (SP; CD4+CD8- or CD4-CD8+) thymocytes (IL-2 +/+, 5.3 x 10(6) vs IL-2 -/-, 20.9 x 10(6)). The latter also bear activation markers. In addition, thymocytes from TNP-KLH-immunized IL-2 -/- mice produce more IFN-gamma and less IL-4 than similarly immunized IL-2 +/+ mice. These defects in thymocyte maturation and lymphokine production are IL-12 driven, since they are prevented when immunized IL-2 -/- mice are coadministered with anti-lL-12. Furthermore, we demonstrate that IL-2 -/- mice exhibit decreased cortical apoptosis as determined by thymocyte numbers and detection of apoptotic cells in situ. Finally, we show that colitis-inducing thymocytes are generated in the immunized IL-2 -/- thymus, since IL-2 +/+ mice develop colitis following injection of small numbers of single positive thymocytes from immunized IL-2 -/- mice but not from IL-2 +/+ mice. Taken together, these data indicate that, in the absence of IL-2, thymocyte maturation is abnormally directed by IL-12 toward the generation of mature, activated Th1-type thymocytes that are capable of mediating colitis.
Cognate T cell help for CD40-deficient B cells induces c-myc RNA expression, but DNA synthesis requires an additional signal through surface Ig.
Authors: Schrader C E , Stavnezer J , Kikutani H , Parker D C 
Published: December 2022

Abstract
To investigate the role of CD40 ligand in the delivery of help to B cells, we examined the Ag-specific interaction of B cells from CD40-deficient mice with a Th2 cell line in vitro. Small resting B cells from normal mice are stimulated to synthesize DNA when they present monovalent Ag (rabbit Fab anti-Ig) to a rabbit Ig-specific Th cell line. This response, which is independent of a signal through the B cell Ag receptor (sIg), is nearly absent in B cells from CD40-deficient mice. The CD40-deficient B cells are not defective in Ag presentation because they induce T cell IL-4 synthesis as well as normal B cells. Also, CD40-deficient B cells respond to T cell help with DNA synthesis almost as well as normal B cells if an additional signal is provided through sIg. In conjunction with a sIg signal, cell contact with helper T cells induces DNA synthesis more effectively than soluble cytokines. CD40-independent T cell help can also be measured as an early increase in c-myc mRNA levels in CD40-deficient B cells presenting Ag to helper T cells, although the levels of c-myc RNA expression are lower than those in normal B cells. However, c-myc RNA induced by noncognate interaction with anti-CD3-activated T cells is completely CD40 dependent. We conclude that early growth signals from activated Th cells are received by CD40-/- B cells, but that CD40 and/or sIg signals are required for efficient induction of DNA synthesis.
B cell epitope mapping of the bacterial superantigen staphylococcal enterotoxin B: the dominant epitope region recognized by intravenous IgG.
Authors: Nishi J I , Kanekura S , Takei S , Kitajima I , Nakajima T , Wahid M R , Masuda K , Yoshinaga M , Maruyama I , Miyata K 
Published: December 2022

Abstract
We showed that i.v. IgG contains Abs against a major group of bacterial superantigens, and that they can inhibit superantigen-elicited T cell activation. The B cell epitope region of the superantigen and the inhibitory mechanism have remained unknown. To analyze the dominant B cell epitopes on the bacterial superantigen SEB (staphylococcal enterotoxin B), we constructed fusion proteins of SEB deletion mutants, and the reactivities of these recombinant proteins to i.v. IgG and healthy human sera were evaluated by means of immunoblotting. Intravenous IgG and healthy human sera mostly recognized the C-terminal fragment (amino acid (aa) 133-239). The C-terminally truncated protein (aa 1-228) and the truncated mutant delta 225-234 lost reactivity, while the truncated protein (aa 1-234) did not, suggesting that the region (aa 225-234) is the dominant B cell epitope. The mutant, in which residues 226-229 of SEB were exchanged for residues 209-212 of streptococcal pyrogenic exotoxin A, reduced the reactivity with the C-terminal region-specific IgG purified by affinity chromatography. The C-terminal region-specific IgG inhibited SEB-elicited T cell activation, suggesting that this Ab that recognizes the epitope functions as the humoral defensive factor against SEB in humans. Furthermore, the assumed epitope region was homology to the residues (aa 32-41) of human thymopoietin, containing the biologic active site.
Characterization of lymphocyte function-associated antigen 1 (LFA-1)-deficient T cell lines: the alphaL and beta2 subunits are interdependent for cell surface expression.
Authors: Weber K S , York M R , Springer T A , Klickstein L B 
Published: December 2022

Abstract
The leukocyte, or beta2, integrins are heterodimeric cell surface molecules that share a common beta subunit, and have unique alpha subunits. LFA-1 is the predominant beta2 integrin on lymphocytes, and plays an important role in many lymphocyte functions; however, most studies of the cytoplasmic regions of LFA-1 have been performed in transfected epithelial cells, such as COS, in part because no lymphoid cell lines deficient in the LFA-1 alpha subunit have been described. To address structure-function studies of beta2 integrins in relevant cell types, two T lymphoblastoid cell clones that completely lack cell surface LFA-1, J-(beta2).7 and SK-(beta2).7, derived from Jurkat and SKW3, respectively, were prepared by chemical mutagenesis and selection. Biosynthetic labeling and immunoprecipitation showed that the J-(beta2).7 clone did not translate any LFA-1 alpha subunit protein, while the SK-(beta2).7 cells did not synthesize any beta2 subunit protein. Northern blot analysis of poly(A+) RNA from these cells revealed an absence of the corresponding mRNA in each case. By transfection analysis, only the alpha subunit reconstituted LFA-1 expression in the J-(beta2).7 cells, while only the beta subunit restored cell surface LFA-1 expression in the SK-(beta2).7 cells. Functional studies with the parental cell lines, the J-(beta2).7 and SK-(beta2).7 cells, and the transfectants showed that all binding of Jurkat and SKW3 cells to purified ICAM-1 is mediated by LFA-1, and the reconstituted LFA-1 expressed by the J-(beta2).7 and SK-(beta2).7 transfected cells is regulated normally.
Immune CD8+ T lymphocytes lyse Listeria monocytogenes-infected hepatocytes by a classical MHC class I-restricted mechanism.
Authors: Jiang X , Gregory S H , Wing E J 
Published: December 2022

Abstract
Hepatocytes constitute the principal site of listerial replication in the livers of mice infected i.v. CD8+ T lymphocytes play a predominant role in the host defenses to Listeria monocytogenes. In vitro experiments by others undertaken to delineate the functions of CD8+ T lymphocytes have focused primarily on their interaction with Listeria-infected macrophages. Such experiments do not address directly the role of CD8+ T lymphocytes in eliminating the bulk of Listeria replicating within the liver. Here, we report that immune CD8+ T cells at an E:T cell ratio &gt; or = 10:1 lysed Listeria-infected hepatocytes as judged by the following two criteria. Aspartate aminotransferase activity in the culture supernatants, indicative of hepatocyte damage, increased significantly. Conversely, infected hepatocytes cocultured with immune CD8+ T cells exhibited a marked reduction in viable intracellular Listeria assessed by CFUs. Neither immune CD4+ T cells nor nonimmune CD8+ T cells caused a similar increase in aspartate aminotransferase activity released or a decrease in intracellular bacteria. Immune CD8+ T cell-mediated lysis of infected hepatocytes was restricted by classical MHC class I (H-2Kb) molecules and was inhibited by the presence of either brefeldin A or mAb specific for CD8. These results suggest that the predominant role of CD8+ T lymphocytes in host resistance to listerial infections of the liver may be due to their capacity to lyse infected hepatocytes.
Albumin nitrosylated by activated macrophages possesses antiparasitic effects neutralized by anti-NO-acetylated-cysteine antibodies.
Authors: Mnaimneh S , Geffard M , Veyret B , Vincendeau P 
Published: December 2022

Abstract
Activated macrophages exert an L-arginine-dependent cytostatic effect on the extracellular parasite, Trypanosoma musculi. This effect is not observed in the absence of albumin in the culture medium but is restored by the addition of albumin, indicating the presence of an albumin-nitric oxide (NO) adduct acting as an effector molecule. Since L-cysteine represents a privileged target for NO, an immunochemical approach was performed using an acetylated-cysteine-BSA conjugate. This conjugate was nitrosylated using sodium nitrite as a NO donor. Binding of NO to the conjugated haptens was assayed using spectrophotometry. It was completely abolished by mercuric chloride, confirming the presence of an S-NO bond. Polyclonal Abs were obtained after immunizing rabbits with S-nitroso-acetylated-cysteine (NO-ac-Cys) conjugates. Using the enzyme-linked immunosorbent assay method, Ab avidity and specificity were determined by competition experiments between NO-ac-Cys-conjugated compounds and other nitrosylated or non-nitrosylated compounds. The resulting cross-reactivity ratios showed that conjugated NO-ac-Cys-BSA was the best recognized compound. These Ab were used for an in vitro study of the kinetics of NO-derived compounds from activated murine macrophages. Anti-NO-ac-Cys Ab inhibited the antimicrobial effect of activated macrophages on the extracellular parasite, T. musculi. Moreover, the L-arginine-dependent antiparasitic activity of supernatants from Calmette-Guerin bacillus-activated macrophages required the presence of albumin and was also inhibited by anti-NO-ac-Cys Ab, showing the effector role of S-nitroso-albumin.
IL-6 produced by macrophages infected with Mycobacterium species suppresses T cell responses.
Authors: VanHeyningen T K , Collins H L , Russell D G 
Published: December 2022

Abstract
The ability of Mycobacterium bovis Calmette-Guérin bacillus-infected bone marrow-derived macrophages to process and present exogenously added Ags to T cells and stimulate their growth and production of IL-2 was examined. The infected macrophages were inhibited in their ability to activate T cells, and this inhibition could be transferred to uninfected macrophages with filtered supernatants from mycobacteria-infected macrophages. The inhibition was not due to decreases in macrophage viability, Ag uptake, or cell surface expression of MHC class II or other accessory molecules necessary for Ag presentation. Other intracellular pathogens such as Listeria monocytogenes and Leishmania mexicana did not induce the soluble inhibitory factor, while Mycobacterium avium strain 101 did, suggesting the factor is specific to infection with mycobacteria. The inhibitory effect was reversed completely by preincubation with neutralizing Abs against IL-6, and rIL-6 partially restored the effect. Approximately 10,000-fold more IL-6 was produced by mycobacteria-infected macrophages compared with uninfected controls. Such sustained levels of IL-6 may account for the immune unresponsiveness apparent in both human and murine mycobacterial disease.
B-1 cell (CD5+B220+) outgrowth in murine schistosomiasis is genetically restricted and is largely due to activation by polylactosamine sugars.
Authors: Velupillai P , Secor W E , Horauf A M , Harn D A 
Published: December 2022

Abstract
Previously, we demonstrated that lacto-N-fucopentaose III, a sugar found on egg Ags of Schistosoma mansoni, stimulated splenic B cells from parasite-infected mice to proliferate and produce IL-10 and PGE2. The major source of B cell IL-10 is the B-1 subset (CD5+B220+). Thus we examined whether levels of peritoneal exudate B-1 cells changed as a consequence of infection. In CBA/J, BALB/c, and C3H/HeJ mice, we observed significant increases in B-1 cells at 2 to 4 wk postinfection, declining to baseline by 6 to 8 wk. In contrast, the percentage of B-1 cells remained unchanged in C57BL/6 and BALB/c X.id mice after infection. B-1 cells were not observed in the spleens of infected mice; however, coincident with peritoneal B-1 cell decline, splenic CD23+B220+ cells increased from 11% to 30%. Peritoneal B-1 cells could also be expanded by injection of soluble egg Ag, but not by its deglycosylated form, suggesting a role for carbohydrates in B-1 recruitment. In addition, these cells secreted in vitro large amounts of IL-10 in response to lacto-N-fucopentaose III. Further, this sugar induced B-1 cell outgrowth in CBA/J and C3H/HeJ mice, but not in C57BL/6 mice. Thus, early activation of polylactosamine-reactive, IL-10-producing peritoneal B-1 and splenic B cells may be related to early dominance of the Th2-type CD4+ T cell subset. The degree to which this occurs may in part explain differences in the degree of granulomatous pathology reported among various strains of mouse.
Regulation of tumor necrosis factor-alpha and IL-1 beta synthesis by thromboxane A2 in nonadherent human monocytes.
Authors: Caughey G E , Pouliot M , Cleland L G , James M J 
Published: December 2022

Abstract
Synthesis of TNF-alpha and IL-1beta, by monocytes/macrophages can be partially regulated by the eicosanoid, PGE2. We report here that inhibition of both PGE2 and thromboxane A2 (TXA2) synthesis by a prostaglandin H synthase inhibitor, NS-398, had no effect on the synthesis of either TNF-alpha or IL-1beta, even though the addition of PGE2 to these treated cells dose-dependently inhibited TNF-alpha and IL-1beta synthesis. Because TXA2 is a major eicosanoid product of stimulated human monocytes, we examined its influence on cytokine production. Inhibition of thromboxane synthase by carboxyheptyl imidazole (CI) resulted in inhibition of TNF-alpha (61 +/- 4.3%; n = 8; p &lt; 0.001) and IL-1beta (54 +/- 4.2%; n = 8; p &lt; 0.001) synthesis by serum-treated zymosan-stimulated nonadherent human monocytes. This effect was observed when cytokine production was measured by ELISA or bioactivity assays. Furthermore, the addition of a TXA2 agonist, carbocyclic TXA2, to CI-treated monocytes dose-dependently restored the levels of TNF-alpha and IL-1beta synthesis to those found with serum-treated zymosan stimulation alone. Inhibition of TXA2 activity by the thromboxane receptor antagonists, pinane TXA2 or SQ 29,548, also inhibited the production of TNF-alpha (67 +/- 2.4% and 65 +/- 2.7%, respectively; n = 8; p &lt; 0.001) and IL-1beta (59 +/- 3.3% and 70 +/- 1.2%, respectively; n = 8; p &lt; 0.001). Treatment with CI resulted in a partial decrease in TNF-alpha mRNA levels (60 +/- 12.0%; n = 4), but had little or no effect on IL-1beta mRNA levels. These novel observations implicate TXA2 as an important paracrine or autocrine facilitator of TNF-alpha and IL-1beta production in stimulated human monocytes and suggest that levels of TNF-alpha and IL-1beta synthesis are determined in part by the balance between TXA2 and PGE2 production in human monocytes.
Priming with IFN-gamma restores deficient IL-12 production by peripheral blood mononuclear cells from HIV-seropositive donors.
Authors: Harrison T S , Levitz S M 
Published: December 2022

Abstract
Production of IL-12 is deficient in PBMC from HIV-infected individuals. Because of recent studies demonstrating that IFN-gamma priming increases the production of IL-12 in normal PBMC, we examined the role of IFN-gamma in the production of IL-12 in PBMC from HIV-seropositive donors. In response to Staphylococcus aureus, production of IFN-gamma and IL-12 was reduced in PBMC from HIV-seropositive compared with that from HIV-seronegative donors. Priming with IFN-gamma, through increases in both IL-12 p40 and p35 mRNA levels, caused a significant increase in IL-12 release by PBMC from both HIV-seropositive and HIV-seronegative donors. However, the increase was greater for PBMC from HIV-seropositive donors, largely restoring the deficit in IL-12 production seen in unprimed cells. In response to Cryptococcus neoformans, Candida albicans, and Mycobacterium tuberculosis, three pathogens that frequently cause opportunistic infections in persons with AIDS, IFN-gamma production was also reduced in PBMC from HIV-seropositive compared with seronegative donors. When primed with IFN-gamma, PBMC from both HIV-seropositive and seronegative donors released substantial and similar quantities of IL-12 in response to these organisms. Taken together, these results demonstrate that IFN-gamma can restore the deficit in IL-12 production seen in HIV infection.
Evidence for B cell-mediated activation of V delta 1+ T lymphocytes during progression of HIV infection.
Authors: Hyjek E M , Bartkowiak J , Drozdz R , Wasik T J , Jasinski M , Kaneko Y , Lischner H W , Kozbor D 
Published: December 2022

Abstract
Progression of HIV-induced immunodeficiency is associated with both B cell activation and an increased proportion of Vdelta1+ T cells in PBL. To examine whether the peripheral expansion of Vdelta1+ cells is driven by activated B cells, we isolated CD19+ PBL from HIV+ individuals at different stages of infection and used them to stimulate Vdelta1+ T cell clones. The Vdelta1+ T cell clones were isolated from HIV+ individuals and selected on the basis of cytotoxic activity and IFN-gamma expression in response to lymphoblastoid cell lines (LCLs) established from patients with AIDS (AIDS-related LCLs) but not LCLs of HIV- donors. Peripheral blood B cells from HIV+ patients induced IFN-gamma expression in these Vdelta1+ clones, and their stimulatory ability was associated with up-regulated expression of the CD38 activation Ag and with a 6- to 10-fold increased spontaneous Ig production. Stimulation of CD19+ PBL from HIV+ individuals with cross-linked anti-CD40 mAb or rgpl20 further augmented induction of IFN-gamma expression in the Vdelta1+ cells. The isolated Vdelta1+ T cell clones expressed the Jdelta1 gene segment, but differed in Vgamma gene segment usage and in the junctional region of TCR-delta chains, indicating Vdelta gene-determined recognition. These results provide evidence that the peripheral expansion of Vdelta1+ cells in HIV infection is associated with phenotypic and functional alterations of B cells, due to chronic activation during progression to AIDS.
Allopeptide-specific T cell reactivity altered by peptide analogs.
Authors: Colovai A I , Liu Z , Harris P E , Cortesini R , Suciu-Foca N 
Published: December 2022

Abstract
Recent evidence indicates that indirect allorecognition plays a key role in initiating and sustaining graft rejection. This self-restricted T cell response is generally limited to a restricted set of dominant immunogenic peptides derived from allogeneic HLA molecules. Here, we have examined whether peptide analogues of the dominant determinant of HLA-DRbeta1*0101 molecule (peptide DR1/22-35), recognized in the context of HLA-DRbeta1*1101 protein, are able to modulate the T cell response against the wild-type peptide Ag. The peptide analogues were generated by introducing single amino acid substitutions at putative MHC and TCR contact positions. Two analogues, 25R/A and 28E/Q, which bound to soluble DR11 protein, but did not stimulate an anti-DR1-specific T cell clone, inhibited the response of the clone to the wild-type peptide by TCR antagonism. Analogs 25R/A and 28E/Q were also able to inhibit the differentiation of Th precursors specific for peptide DR1/22-35. Two other peptides, 26L/I and 27L/V, acted as powerful TCR agonists, inducing a higher proliferative response of the DR1-specific T cell clone, compared with the wild-type peptide. At high concentrations, these peptides induced hyporesponsiveness of TCC-ZL36 in a manner similar to the wild-type peptide. Taken together, the results of this study indicate that specific suppression of indirect allorecognition can be achieved by using structural variants of the dominant allodeterminant.
C1q binds directly and specifically to surface blebs of apoptotic human keratinocytes: complement deficiency and systemic lupus erythematosus revisited.
Authors: Korb L C , Ahearn J M 
Published: December 2022

Abstract
Complete deficiency of C1q is almost invariably associated with the development of systemic lupus erythematosus. It has been suggested that this association may result from a generalized failure to clear Ag-Ab complexes. However, it has not been demonstrated how such a broad impairment results in this specific and consistent autoimmune phenotype, in which photosensitive skin disease is the most prominent manifestation. We believe there is another role for the classical pathway in maintaining immune tolerance. Surface blebs of apoptotic keratinocytes are concentrated sources of autoantigens, and these packages may define a novel immune context and challenge self-tolerance if not properly cleared and processed. We demonstrate here that when human keratinocytes are rendered apoptotic, they also develop the capacity to specifically and directly bind to C1q in the absence of Ab. C1q may mediate Ab-independent clearance of apoptotic keratinocytes, and prevent immunization with autoantigens of cutaneous origin.