bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular targets of CD45 in B cell antigen receptor signal transduction.
Authors: Pao L I , Bedzyk W D , Persin C , Cambier J C 
Published: December 2022

Abstract
Expression of the phosphotyrosine phosphatase CD45 is essential for B cell Ag receptor (BCR)-mediated p21ras activation and calcium mobilization. To examine the molecular basis of this requirement, we analyzed signaling events following BCR ligation in CD45-deficient (CD45-) and CD45-reconstituted (CD45+) variants of J558Lmicrom3 cells. Ag stimulation resulted in tyrosine phosphorylation of cellular proteins in both cells. However, the spectrum of proteins phosphorylated in the CD45+ cells was qualitatively and/or quantitatively distinct from that in the CD45- cells. Among the protein tyrosine kinases examined, the Src family kinases Fyn and Blk were inducibly tyrosine phosphorylated and activated by receptor ligation only in CD45+ cells. While Ag-induced Btk tyrosine phosphorylation occurred in both cells, its activation was greatly diminished in the CD45- cells. Analysis of specific effector molecules revealed that tyrosine phosphorylation of Shc, but not rasGAP or Vav, correlated with the unique ability of BCR ligation to trigger p21ras activation in CD45+ cells. BCR-mediated Shc phosphorylation and recruitment of Grb2 depended on CD45 expression. Thus, Shc tyrosine phosphorylation may be the primary CD45-dependent mechanism by which Ag receptors are coupled to the p21ras pathway in J558Lmicrom3. In addition, phospholipase Cgamma1 (PLCgamma1) and PLCgamma2 were tyrosine phosphorylated upon Ag stimulation in CD45- cells, despite much reduced inositol trisphosphate production and lack of calcium mobilization. These findings suggest that CD45 may modulate events other than PLCgamma phosphorylation, which regulate phosphoinositide hydrolysis and the calcium mobilization response following BCR ligation.
Optimal T cell activation by melanoma cells depends on a minimal level of antigen transcription.
Authors: Labarriere N , Diez E , Pandolfino M C , Viret C , Guilloux Y , Le Guiner S , Fonteneau J F , Dreno B , Jotereau F 
Published: December 2022

Abstract
We reported previously that a large fraction of melanoma cell lines induced a suboptimal activation of specific CTL clones, characterized by good tumor cell lysis but no detectable IL-2 production. Using synthetic peptides, we demonstrated recently that this was due to expression of subthreshold levels of appropriate MHC-peptide complexes. We measure here by semiquantitative reverse transcription-PCR the expression of two melanoma Ag (NA17-A and Melan-A/MART-1) mRNAs in 13 melanoma cell lines and analyze the responses to these cell lines of specific HLA-A2-restricted CTL clones. In line with the idea that the density of MHC-antigenic peptide complexes on melanoma cells is a direct function of the Ag's mRNA level, we found that CTL lysis was grossly proportional to this level. We also established that a minimal level of transcription is required for melanoma cells to induce IL-2 secretion. Interestingly, all cell lines that expressed the Ag above this minimal level, either spontaneously or after gene transfection, stimulated the secretion by tumor-infiltrating lymphocyte of IL-2 amounts proportional to Ag expression unless they exhibited a defective expression of intracellular adhesion molecule-1 or LFA-3 molecules or a low expression of the restricting HLA element. These results indicate that optimal activation and therefore, doubtless, full functionality of melanoma-specific CTL clones critically depend on the mRNA level of the Ag in tumor cells and also on a minimal expression of the HLA restriction element, intracellular adhesion molecule-1, and LFA-3. These data provide a rationale for a better selection of patients to be included in Ag-specific immunization protocols.
Single immunizing dose of recombinant adenovirus efficiently induces CD8+ T cell-mediated protective immunity against malaria.
Authors: Rodrigues E G , Zavala F , Eichinger D , Wilson J M , Tsuji M 
Published: December 2022

Abstract
The immunogenicity of a recombinant replication defective adenovirus expressing a major malaria Ag, the circumsporozoite (CS) protein (AdPyCS), was determined using a rodent malaria model. A single immunizing dose of this construct induced a large number of CS-specific CD8+ and CD4+ T cells in the spleens of these animals, particularly when given by the s.c. or i.m. route. A single dose of AdPyCS also induced high titers of Abs to Plasmodium yoelii sporozoites in mice. No other form of presentation of the CS protein given as a single immunizing dose, i.e., irradiated sporozoites, recombinant vaccinia, or influenza virus, etc., elicits comparably high numbers of CS-specific CD8+ T cells. The high concentration of CS-specific CD8+ T cells in the spleen was relatively short-lived, decreasing to half of its original value by 4 wk and to one-third at 8 wk after AdPyCS inoculation. The decrease in splenic CS-specific CD4+ T cells was even more rapid. Most importantly, a single dose of inoculation of AdPyCS into mice rendered them highly resistant to sporozoite challenge, resulting in a 93% inhibition of liver stage development of the parasites. This protective effect was primarily mediated by CD8+ T cells, as shown by depletion of this T cell population, while depletion of the CD4+ T cell population had only a minor effect on anti-plasmodial activity. Moreover, the inoculation of mice with AdPyCS induces sterile immunity in a significant proportion of mice, preventing the occurrence of parasitemia.
A Ca2+-dependent autoregulation of lipopolysaccharide-induced IL-8 receptor expression in human polymorphonuclear neutrophils.
Authors: Bhattacharya C , Samanta S , Gupta S , Samanta A K 
Published: December 2022

Abstract
IL-8, a potent neutrophil chemotactic agent, is known to be a key mediator in several inflammatory diseases. We found that 10 ng/ml of serum-activated LPS (Escherichia coli) efficiently up-regulated IL-8R on the surface of neutrophils within 30 min of LPS stimulation by 115 to 120% through de novo protein synthesis. After 30 min of LPS stimulation, reduction of IL-8R level was initiated and the normal level was restored within 2 h of LPS interaction. EDTA or EGTA and bestatin separately inhibited the receptor down-regulation by 98%, indicating the involvement of metalloprotease(s), more specifically an aminopeptidase in the process. Induction and subsequent reduction of IL-8 binding in serum-activated LPS-stimulated cells have been demonstrated in autoradiography. Intracellular Ca2+ level in these stimulated neutrophils was increased and decreased with alteration of IL-8R level. Although IL-8 binding was drastically reduced, the total IL-8R level, as detected by anti-IL-8R Ab measured by 125I-labeled anti-rabbit IgG, remained almost unaltered, indicating that minimal proteolysis occurred in IL-8R. Anti-IL-8R Ab and IL-8 itself could prevent this down-regulation significantly, suggesting that the susceptible epitope(s) might be in the IL-8 binding domain of the receptor. Under Ca2+-depleted conditions, the proteolysis was inhibited, which was accelerated upon addition of 1 mM of CaCl2. The study demonstrates that LPS-induced up-regulation of IL-8R leads to amplified IL-8-mediated biologic responses of neutrophils that are restored to normal level by activation of a Ca2+-dependent aminopeptidase. This may be useful for understanding the regulation of LPS-mediated inflammatory responses of neutrophils during bacterial infection.
Expression and release of the monocyte lipopolysaccharide receptor antigen CD14 are suppressed by glucocorticoids in vivo and in vitro.
Authors: Nockher W A , Scherberich J E 
Published: December 2022

Abstract
The effect of glucocorticoid (GC) treatment on expression and release of the monocyte cell surface LPS receptor Ag CD14 was studied in vivo and in vitro. In patients with acute inflammatory diseases receiving GC pulse therapy serum concentrations of soluble CD14 and CD14 expression by peripheral blood monocytes decreased significantly. The LPS-binding capacity correlated positively with the amount of cell surface CD14 by human blood monocytes. In vitro, a time- and dose-dependent effect of GC preparations on monocyte membrane and soluble CD14 by cultured peripheral blood monocytes was found. Incubation with 2 x 10(-8) M prednisolone down-regulated cell surface CD14 after 72 h, and 2 x 10(-7) M suppressed CD14 expression even after 24 h. Prednisolone also decreased release of the soluble CD14 Ag, where a 10-fold higher GC concentration was required for a significant suppression compared with membrane CD14 during culture. Expression of other monocyte membrane Ags were either unchanged (CD33, CD35), diminished (CD13, CD89), or increased (CD32) by GC, indicating no general down-modulation of cell surface Ag expression. Preincubation with glucocorticoids for 24 h significantly down-regulated CD14 expression during subsequent steroid-free culture for at least 7 days. In cultured monocytes, the LPS-induced increase of membrane and soluble CD14 was markedly but not completely inhibited by prednisolone. Therefore, GC treatment suppresses the up-regulation of the LPS receptor during endotoxin challenge, and likewise, the IL-1 secretion after LPS stimulus was significantly diminished. Taken together, the suppression of the monocytic cell surface and soluble endotoxin receptor CD14 by GC may contribute to the increased risk of infections in patients undergoing steroid therapy.
Chemoattractant cross-desensitization of the human neutrophil IL-8 receptor involves receptor internalization and differential receptor subtype regulation.
Authors: Sabroe I , Williams T J , Hébert C A , Collins P D 
Published: December 2022

Abstract
Human neutrophils undergo rapid homologous receptor desensitization following repeated stimulation with chemoattractants such as IL-8, C5a, and FMLP. It has also been demonstrated that cross-desensitization among these chemoattractant receptors occurs. We investigated the mechanisms underlying the cross-desensitization of responses to IL-8 induced by pretreatment with FMLP or C5a. In [125I]-labeled IL-8 binding studies we found that the cross-desensitization induced by FMLP or C5a was associated with a subsequent reduction in IL-8 binding to neutrophils. There was no recovery of [125I]-labeled IL-8 binding on removal of the C5a or FMLP pretreatment. FACS analysis using mAbs specific for the two IL-8R subtypes showed differential regulation of IL-8R A and IL-8R B cell surface expression after chemoattractant pretreatment. Homologous desensitization by IL-8 resulted in internalization of IL-8R A and IL-8R B, but only IL-8R A was completely re-expressed after removal of agonist. FMLP stimulation led to a substantial loss of IL-8R B from the cell surface, whereas C5a stimulation induced only a partial loss. In both cases there was no re-expression of IL-8R B on removal of the chemoattractant stimulation. C5a and FMLP did not affect IL-8R A expression. Calcium mobilization studies using melanoma growth stimulatory activity and IL-8 suggest that a sustained loss of IL-8R B may play a part in maintaining FMLP-induced IL-8R cross-desensitization. Chemoattractant-induced cross-desensitization of neutrophils may be of importance in regulating neutrophil accumulation during the inflammatory response in vivo.
Roles of IL-4 and IL-12 in the development of lupus in NZB/W F1 mice.
Authors: Nakajima A , Hirose S , Yagita H , Okumura K 
Published: December 2022

Abstract
Development of either Th1 or Th2 cell subsets has profound immunologic consequences, either pathogenic or protective, in several autoimmune diseases. However, it remains unclear which subset of Th cells plays a more critical role in lupus. In this study, we examined IL-4 and IL-12, which play decisive roles in the development of Th2 and Th1, respectively, in the IgG autoantibody production and development of lupus nephritis in NZB/W (B/W) F1 mice. Transfer of either IL-4- or IL-12-stimulated splenocytes from 5-mo-old B/W F1 mice into B/W F1 mice of the same age enhanced the production of IgG anti-dsDNA Ab. Consistently, administration of mAb against either IL-4 or IL-12 before the onset of lupus could inhibit the production of IgG anti-dsDNA Ab. However, only anti-IL-4 mAb was effective in preventing the onset of lupus nephritis. This discrepancy appeared to be explained by the differential effect on the production of IgG3-type autoantibody and TNF production. Interestingly, when combined, anti-IL-12 mAb abrogated the beneficial effect of anti-IL-4 mAb. These results indicate that both Th2 and Th1 contribute to the IgG autoantibody production, and IL-4 and IL-12 play key roles in the complexity of cytokine regulation in the pathogenesis of autoimmunity in lupus, but the former is more critical.
The role of hepatitis C virus-specific cytotoxic T lymphocytes in chronic hepatitis C.
Authors: Nelson D R , Marousis C G , Davis G L , Rice C M , Wong J , Houghton M , Lau J Y 
Published: December 2022

Abstract
Cellular immune responses, particularly those mediated by CD8+ CTL, may be important in the pathogenesis and control of hepatitis C virus (HCV) infection. To define the role of HCV-specific CTL in chronic hepatitis C, HCV-specific CTL activity in liver and peripheral blood was assessed in 35 patients with chronic HCV infection and 5 non-HCV controls. HCV-specific CTL activity of expanded CD8+ cells was evaluated against autologous lymphoblastoid cells transduced with recombinant vaccinia virus vectors expressing HCV genotype 1a Ags. CTL activity was detected in unprimed bulk-expanded CD8+ cells derived from the liver in 16 of the 35 patients, but not in peripheral circulation. Three patients infected with non-type 1 HCV were found to have HCV-specific CTL activity against HCV type 1a epitopes, all directed toward HCV core region. Compared with patients without detectable HCV-specific CTL activity based on our assay, those exhibiting CTL activity had lower levels of viremia (p &lt; 0.01 for both branched DNA version 1.0 and 2.0 assays) and more active disease, as reflected by a higher histologic activity index (p = 0.006) and serum alanine aminotransferase levels (p = 0.03). It is concluded that 1) with nonspecific stimulation, HCV-specific CTL activity is found more commonly in the liver than in peripheral circulation, suggesting a tissue-specific localization with HCV-specific CTL and/or its precursors; 2) cross-genotype CTL activity exists, especially toward HCV core, which is relatively conserved across genotypes; and 3) patients with intrahepatic HCV-specific CTL activity had lower levels of viremia and more active liver disease.
Regulation of CD28 costimulation in human CD8+ T cells.
Authors: Lloyd T E , Yang L , Tang D N , Bennett T , Schober W , Lewis D E 
Published: December 2022

Abstract
Optimal stimulation and prevention of anergy in T cells requires signaling through the CD28 molecule. During HIV disease progression, CD28 expression is lost, particularly on CD8+ T cells. Because alterations in cytokine production patterns occur during HIV infection, we determined whether CD8+ T cell phenotype or function was affected by cytokine environment. Treatment of CD8+ T cells with IL-4 decreased levels of both CD28 surface expression and message and increased CD8 expression. Furthermore, CD8+ T cells that had down-regulated CD28 had reduced proliferative capacity. The inhibitory effects of CD28 reduction could be compensated either by increased anti-CD3 or by exogenous IL-2, suggesting that the strength of T cell signaling necessary for the production of IL-2 and subsequent proliferation is negatively regulated by IL-4. CD8+ subpopulations with differential CD28 expression produced different patterns of cytokines, particularly IL-2 and IFN-gamma. Furthermore, CD8+ T cells that had reduced CD28 levels but made their own IL-2 were able to proliferate in response to TCR stimulation. These results suggest that loss of CD28 expression and CD8 T cell function can be regulated by the cytokine environment, which may be altered during HIV disease progression. Whether the dysfunction of CD8+ T cells in HIV infection occurs by such a mechanism is the subject of future investigation.
Surface expression of hemopoietic cell phosphatase fails to complement CD45 deficiency and inhibits TCR-mediated signal transduction in a Jurkat T cell clone.
Authors: Musci M A , Beaves S L , Ross S E , Yi T , Koretzky G A 
Published: December 2022

Abstract
Previous studies have shown that the protein tyrosine phosphatase CD45 is required for initiation of signal transduction through several lymphoid receptors. In contrast, there is increasing evidence that another protein tyrosine phosphatase, hemopoietic cell phosphatase (known as HCP, SHP, PTP1C, SHPTP-1, or PTPN6), is a negative regulator of signaling in hemopoietic cells. To determine the effect of HCP on signal transduction through the TCR, HCP was expressed as a chimeric molecule with extracellular and transmembrane domains of the HLA-A2 molecule (A2/HCP) on wild-type Jurkat T cells and the CD45-deficient variant, J45.01. In this report, we show that expression of A2/HCP, unlike A2 chimeras containing the enzymatic regions of CD45, fails to rescue TCR-mediated signal transduction in J45.01. Furthermore, expression of A2/HCP on wild-type Jurkat T cells results in diminished inositol phosphate production following TCR ligation as well as markedly diminished nuclear factor of activated T cells promoter activity. Surprisingly, however, TCR-mediated tyrosine phosphorylation of phospholipase C gamma 1 remains intact in the Jurkat cells expressing the A2/HCP chimera. These experiments provide further evidence that HCP can serve a negative regulatory role in receptor-mediated signaling in immune cells. Additionally, our studies suggest that surface expression of HCP in T cells may provide a means to identify phosphotyrosine-containing proteins that are required for coupling signaling pathways initiated by ligation of the T cell Ag receptor.
Type 2 helper T cell-type cytokines and the development of "infectious" tolerance in rat cardiac allograft recipients.
Authors: Onodera K , Hancock W W , Graser E , Lehmann M , Sayegh M H , Strom T B , Volk H D , Kupiec-Weglinski J W 
Published: December 2022

Abstract
CD4-targeted therapy with a nondepleting RIB-5/2 mAb abrogates accelerated (&lt; 36 h) rejection in presensitized LEW rats and results in permanent acceptance of LBNF1 cardiac allografts in conjunction with the features of infectious tolerance. This study examined the role and functional significance of the Th1 and Th2 cytokine network and systemic host allospecific Ab (allo-Ab) responses in the development of the infectious tolerance pathway in this model. Long term survival of cardiac transplants in rats treated with the tolerizing RIB-5/2 mAb regimen was accompanied by profound depression of Th1 (IL-2 and IFN-gamma) and Th2 (IL-4, IL-10) cytokines at the graft site, as shown by competitive template reverse transcription-PCR and immunohistochemistry. In contrast, the expression of Th2-type cytokines was selectively up-regulated after transfer of infectious tolerance by spleen cells into new generations of primary and secondary test recipients. Donor-specific circulating IgM allo-Ab responses were diminished throughout, and the switch from IgM to IgG allo-Ab was completely prevented in tolerant hosts, as shown by flow cytometry. The demonstration that treatment with cytolytic anti-CD4, but not anti-CD8, mAb recreated rejection of test cardiac allografts with simultaneous down-regulation of IL-4 mRNA/protein expression underlines the importance of this cytokine in the development of infectious tolerance. Hence, this report documents distinct cytokine elaboration patterns in animals tolerized by CD4-targeted therapy compared with those rendered tolerant by putative regulatory Th2-like cells. The mechanism of tolerance in anti-CD4 mAb-treated hosts appears distinct from that operating in the absence of mAb, when the tolerant state is being transferred in an infectious manner to new cohorts of test recipients.
Function of lymphocyte homing-associated adhesion molecules on human natural killer and lymphokine-activated killer cells.
Authors: Uksila J , Salmi M , Butcher E C , Tarkkanen J , Jalkanen S 
Published: December 2022

Abstract
We have analyzed the ability of fresh and rIL-2-activated human NK cells to interact with high endothelial venules (HEV) that are known to support physiologic lymphocyte extravasation, and examined the role of different adhesion molecules in this process. In in vitro HEV-binding assays, NK cells bound to both peripheral lymph node (pLN) and mucosal HEV. Activation by rIL-2 slightly decreased adherence to pLN HEV, but increased adherence to mucosal high endothelium. Markedly fewer NK cells than PBL expressed L-selectin, and the expression was diminished further upon treatment with rIL-2. Inhibition studies showed, however, that L-selectin was the most important single molecule to mediate adhesion to pLN HEV. Binding to mucosal HEV was mediated mainly by CD44 and alpha 4 integrin, and the expression level of these molecules was increased by rIL-2, paralleling the results in HEV-binding assays. Higher m.w. forms of CD44, representing differentially glycosylated/variant forms of CD44, were more abundant on large granular lymphocytes than on unseparated PBL. We conclude that, despite weak recirculatory capacity, NK cells or a subpopulation of NK cells with the correct adhesion molecules can interact with and bind to high endothelial cells. Lymphokines can modulate the expression of adhesion molecules that NK cells utilize for HEV binding. Our results suggest that activation of NK cells with IL-2 may facilitate the extravasation of lymphokine-activated killer cells, especially to mucosal sites, whereas homing to peripheral lymphoid tissues may be diminished. This should be taken into consideration when procedures for lymphokine-activated killer cell immunotherapy are planned.
The 14.1 surrogate light chain promoter has lineage- and stage-restricted activity.
Authors: Donohoe M E , Blomberg B B 
Published: December 2022

Abstract
The 14.1 surrogate light chain protein is expressed on human pre-B lymphocytes in association with Vpre-B and the mu Ig heavy chain to form the pre-B receptor. The 14.1 chain has also been called the lambda (lambda)-like (LL) protein and is homologous to murine lambda5. The 14.1(IGLL1) gene is expressed in a lineage- and stage-restricted manner. To understand the molecular mechanism of the 14.1 gene tissue- and stage-specific expression, we analyzed the 5'-flanking region and characterized the promoter for this gene. In this report, we identify two DNase I-hypersensitive sites located at 2.6 kilobases (HSS 1) and 0.2 kilobases (HSS 1) upstream of 14.1 exon 1. These hypersensitive sites are present in pre-B lymphocyte cell lines, but absent in mature B and T cell lines. We have used RNase protection analysis to localize the 5' major transcriptional start site and rapid amplification of 5' cDNA ends to identify multiple start sites within the TATA-less, GC-rich 14.1 promoter. The region encompassing HSS 2 was analyzed for promoter activity. Transfection of cell lines with a series of truncated segments of the 5' flanking region linked to the luciferase reporter gene revealed that the 14.1 promoter is lineage- and stage-specific, and we localized this activity to positions +150 to +227 relative to the 5' major transcriptional start site.