bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of transport of newly assembled, T cell-stimulatory MHC class II-peptide complexes from MHC class II compartments to the cell surface.
Authors: Pond L , Watts C 
Published: January 2023

Abstract
In human B cells MHC class II molecules acquire antigenic peptides in lysosome-related compartments called the MHC class II compartments (MIIC). How assembled complexes, capable of activating T cells, then reach the cell surface has not been fully resolved. We have used selective ablation of early and recycling endosomes to determine whether newly peptide-loaded class II molecules require functional recycling endosomes to exit to the cell surface. Cellular compartments accessed by transferrin-horseradish peroxidase conjugates were functionally inactivated by cross-linking with diaminobenzidine and hydrogen peroxide. Cells with ablated endosomal compartments were unable to recycle transferrin to the cell surface and could not deliver exogenous Ag for processing and presentation to T cells. In contrast, cells that had taken up Ag and assembled intracellular class II-peptide complexes before endosome ablation were still able to deliver class II-peptide complexes to the cell surface and stimulate T cell proliferation. This delivery was abolished in the presence of brefeldin A. These data show that the parts of the endocytic apparatus necessary for Ag delivery to the MIIC are not required for functional class II-peptide complexes to reach the cell surface. Moreover, the brefeldin A sensitivity of this final step in the class II molecule biosynthetic pathway suggests a vesicular intermediate for transport between the MIIC and the plasma membrane.
The role of protein kinase C in CD8+ T lymphocyte effector responses.
Authors: Nesic D , Jhaver K G , Vukmanović S 
Published: January 2023

Abstract
Rare CD8+ T cells present in beta2microglobulin-deficient (beta2m-/-) mice reject allogeneic tumors but not syngeneic wild-type tumors. The lack of syngeneic tumor rejection in vivo is correlated with a partial response of beta2m-/- CD8+ cell lines to syngeneic tumor cells in vitro. This partial response is characterized by perforin/granzyme-mediated cytolytic activity in the absence of cytokine secretion or proliferation. Allogeneic tumors induce cytolysis, cytokine secretion, and proliferation. Cytokine secretion may therefore be an important effector mechanism for tumor rejection by CD8+ T cells. To determine the missing signaling events needed for cytokine secretion as well as the events inducing the isolated cytotoxic response, we attempted to restore cytokine secretion of beta2m-/- CD8+ cells to syngeneic MHC class I. Phorbol ester and syngeneic tumor cells acted synergistically to induce full responsiveness of beta2m-/- CD8+ cells. However, this synergistic induction of cytokine secretion used a different pathway than that induced by alloantigen. Protein kinase C (PKC) inhibitor prevented the syngeneic class I plus PMA-induced cytokine secretion, but not allo-class I-induced cytokine secretion. In contrast to the PKC independent alloantigen-induced cytokine secretion, cytolysis of both allogeneic and syngeneic targets was PKC dependent. The differential dependence of effector functions on PKC activation was also found in beta2m+/+ CD8+ T cells. Thus, two distinct signaling pathways (PKC dependent and PKC independent) may ultimately converge to induce cytokine secretion in CD8+ cells. The TCR engagement-initiated pathway is PKC independent, whereas the phorbol ester-activated pathway is PKC dependent.
Inflammatory cytokines enhance the in vivo clonal expansion and differentiation of antigen-activated CD4+ T cells.
Authors: Pape K A , Khoruts A , Mondino A , Jenkins M K 
Published: January 2023

Abstract
Despite the wealth of information on the signals required for T cell activation in vitro, the signals required for the generation of functional Th cells in vivo are poorly understood. We addressed this by directly tracking the behavior of adoptively transferred CD4+ TCR transgenic T cells following Ag administration in vivo. Injection of soluble Ag induced a transient accumulation of Ag-specific T cells in lymphoid tissue. If bacterial LPS was present during this period, enhanced numbers of Ag-specific T cells accumulated, migrated into B cell-rich follicles, and provided help for Ab production. The ability of LPS to enhance the accumulation and follicular migration of Ag-activated T cells was mimicked by the proinflammatory cytokines, TNF-alpha and IL-1, and the capacity of LPS to promote the generation of IFN-gamma-secreting T cells, which provide help for IgG2a production, was mimicked by IL-12. Thus, the in vivo generation of functional Th cells can arise from Ag-dependent clonal expansion in the context of inflammatory cytokines.
The 25-kDa soluble CD23 activates type III constitutive nitric oxide-synthase activity via CD11b and CD11c expressed by human monocytes.
Authors: Aubry J P , Dugas N , Lecoanet-Henchoz S , Ouaaz F , Zhao H , Delfraissy J F , Graber P , Kolb J P , Dugas B , Bonnefoy J Y 
Published: January 2023

Abstract
CD23, a low-affinity receptor for IgE, was recently shown to bind to CD11b and CD11c molecules on human monocytes. The 25-kDa soluble fragment of CD23 (sCD23), was tested for its capacity to elicit various signaling pathways in human monocytes. sCD23 was found to trigger an early increase in cGMP accumulation, through the generation of nitric oxide. This was a result of activating the L-arginine pathway, since the sCD23-mediated effect was inhibited in the presence of substituted nonmetabolizable L-arginine analogues. In addition, the increase in cGMP was suppressed by calcium chelators and inhibitors of the calcium/calmodulin complex, suggesting the involvement of a constitutive, calcium-dependent nitric oxide synthase (NOS). Indeed, the presence of an endothelial constitutive type III NOS mRNA was detected in nonactivated human monocytes, and the corresponding protein has been detected by flow cytometry. Moreover, sCD23 was shown to induce a calcium influx in monocytes, in accordance with an activation of a constitutive NOS through a transient increase in [Ca2+]i. As expected, these events were mimicked by mAbs against CD11b and CD11c, the macrophage receptors for CD23. In addition to these early events, sCD23 and the agonistic anti-CD11b and CD11c mAbs, which all trigger the release of proinflammatory mediators such as TNF-alpha, were shown to act through an NO-dependent process.
Activation of human dendritic cells following infection with Mycobacterium tuberculosis.
Authors: Henderson R A , Watkins S C , Flynn J L 
Published: January 2023

Abstract
Dendritic cells (DC) play an essential role in the initiation of primary T cell responses to foreign Ag. It is likely that these potent APC are critical in the initiation of immune responses to pathogens, such as bacteria or parasites. However, little is known about the interaction of these important APC with pathogens. To address this issue, the interaction of the bacterium Mycobacterium tuberculosis with human DC was studied. DC generated from human peripheral blood by short term culture in medium containing recombinant human cytokines granulocyte-macrophage-CSF and IL-4 were capable of phagocytosing M. tuberculosis. Infection of DC with live M. tuberculosis bacilli resulted in increased APC surface expression of the costimulatory molecules CD54, CD40, and B7.1, as well as MHC class I molecules. In addition, infected DC secreted elevated levels of inflammatory cytokines, including TNF-alpha, IL-1, and IL-12. M. tuberculosis-infected human monocytes also secreted inflammatory cytokines, but exhibited no enhancement of costimulatory or MHC class I molecule expression. These data indicate that infection with M. tuberculosis results in the direct activation and maturation of these DC. In vivo, such activation may facilitate migration to the lymph nodes, and enhance presentation of Ag to T cells, thereby facilitating the induction of the immune response against this pathogen.
Migration and activation of antigen-specific CD8+ T cells upon in vivo stimulation with allogeneic tumor.
Authors: Kedl R M , Mescher M F 
Published: January 2023

Abstract
The response of CD8+ T cells to allogeneic tumor was studied by adoptive transfer of cells from TCR transgenic 2C mice specific for Ld alloantigen. Transferred cells were monitored during the course of a response to i.p. challenge with live P815 (H-2d) using the 1B2 mAb specific for the 2C TCR. Tumor was present in the draining LN and spleen within 3 to 4 days of challenge. The first changes in 1B2+ cells occurred in the spleen on day 4; VLA-4 expression increased in an Ag-specific manner and L-selectin expression decreased in an Ag-nonspecific manner. The number of 1B2+ cells in the spleen declined over days 4 to 6. The first detectable increase in CD25 expression and blast transformation was in the peritoneal cavity beginning days 5 and 6. Clonal expansion was largely limited to this site and was maximal on day 8. As expansion occurred in the peritoneal cavity; the number of 1B2+ cells in the draining LN and spleen also increased. These cells had an activated phenotype (CD44(high), VLA-4(high)) but most did not express CD25 and were not blasts. These results suggest that initial Ag recognition in the spleen results in altered expression of adhesion receptors so that cells gain access to the peritoneal cavity where they undergo clonal expansion and differentiation. Following the response, 1B2+ cells decline in number but a memory population (CD44(high), L-selectin(high and low)) persists for long times in the spleen and LN.
A new 12-kilodalton dimer associated with pre-TCR complex and clonotype-independent CD3 complex on immature thymocytes.
Authors: Takase K , Wakizaka K , von Boehmer H , Wada I , Moriya H , Saito T 
Published: January 2023

Abstract
We have characterized the pre-TCR/CD3 complex and the clonotype-independent CD3 (CIC) complex expressed on the cell surface of the immature cell line KKF which we previously identified as the cell line expressing only TCR beta-chain associated with the CD3 complex on the cell surface. We now show that KKF expresses the pT alpha-beta heterodimer-CD3 complex and also the CIC complex on the cell surface by surface biotinylation. In addition, not only the CIC complex but also the pT alpha-beta complex was found to be associated with the molecular chaperon calnexin. Whereas the CD3 zeta-chain was very weakly associated with the pre-TCR/CD3 complex, a 12-kDa molecule (designated pTAC12 as pre-TCR-associated chain) was more stably associated as a dimer with the pre-TCR complex as well as the CIC complex on KKF cells. The significance of pTAC12 dimer in the CD3 complex of immature thymocytes in vivo was demonstrated by coprecipitation of pTAC12 with the CD3 complex in thymocytes from SCID mice. These results show that pTAC12 is a component of the pT alpha-beta complex as well as the CIC complex, and they suggest that pTAC12 may play a role in signaling through and/or in the expression of the pre-TCR/CD3 complex.
CD50 monoclonal antibodies inhibit neutrophil activation.
Authors: Skubitz K M , Campbell K D , Skubitz A P 
Published: January 2023

Abstract
The constitutive high expression of CD50 (ICAM-3) on resting leukocytes, coupled with the observation that CD50 is the primary LFA-1 ligand on resting T cells, suggests that CD50 may be an important LFA-1 ligand in the initiation of the immune/inflammatory response. CD50 mAbs have been reported to increase homotypic adhesion of lymphocytes, and lymphocyte adhesion to HUVEC and extracellular matrix proteins. In this study, the effects of CD50 mAbs on neutrophil activation were examined. CD50 mAbs were found to inhibit neutrophil adhesion induced by FMLP and 12-O-tetradecanoyl-phorbol-13-acetate to resting and TNF-activated HUVEC. CD50 mAbs also inhibited neutrophil adhesion stimulated by CD66a, CD66b, CD66c, and CD66d mAbs to HUVEC. CD50 mAbs inhibited the up-regulation of CD11b/CD18 to the neutrophil surface, and the down-regulation of surface CD62L expression. The potential contribution of src family kinases to the previously described tyrosine kinase activity associated with CD50 in neutrophils was also examined. hck and lyn were found to account for much of the tyrosine kinase activity associated with CD50 in neutrophils. The data indicate that CD50 in neutrophils functions not only as a potential ligand for LFA-1, but also regulates the surface expression and activity of CD11b/CD18 and CD62L. In contrast to the effects in lymphocytes, CD50 appears to function as a negative regulator of neutrophil activation.
TNF-alpha-mediated expression of the receptor for anaphylatoxin C5a on neurons in experimental Listeria meningoencephalitis.
Authors: Stahel P F , Frei K , Eugster H P , Fontana A , Hummel K M , Wetsel R A , Ames R S , Barnum S R 
Published: January 2023

Abstract
The anaphylatoxin C5a has been implicated in the pathogenesis of bacterial meningitis as a potent mediator of inflammation in the subarachnoid space. We investigated the expression of the receptor for C5a (C5aR) in brains of mice with experimental Listeria monocytogenes (LM) meningoencephalitis. In the course of the disease, infiltrating cells in the meninges and the ventricles were found to express C5aR mRNA and protein. In the brain parenchyma, very low constitutive C5aR expression was seen on pyramidal neurons and Purkinje cells. However, in LM-infected mice, a dramatic increase in C5aR expression occurred on neurons starting 6 h after infection and was maximal between 24 and 36 h. TNF-alpha was identified as an essential mediator of neuronal C5aR expression, since mice lacking the genes for TNF and lymphotoxin-alpha (TNF/lymphotoxin-alpha -/- mice) showed significantly attenuated C5aR expression after LM infection. Furthermore, i.p. injection of recombinant TNF-alpha induced enhanced C5aR expression in the brains of TNF/lymphotoxin-alpha -/- mice and in normal animals even in the absence of a bacterial infection. We also assessed the levels of anaphylatoxin C5a in the cerebrospinal fluid of patients with infectious meningitis. C5a was detected in all patients with bacterial meningitis (n = 9), in 6 of 18 patients with aseptic meningitis, and in 1 of 66 control patients. The finding of TNF-alpha-mediated C5aR expression on neurons in experimental Listeria meningitis and the detection of the ligand, C5a, in the cerebrospinal fluid of human patients with infectious meningitis present new directions in the investigation of the pathophysiologic sequelae leading to secondary brain damage.
Chemokine expression in experimental tubulointerstitial nephritis.
Authors: Tang W W , Qi M , Warren J S , Van G Y 
Published: January 2023

Abstract
Chemokines may be important in the pathogenesis of leukocyte infiltration in tubulointerstitial nephritis associated with glomerular disease. We studied the renal cortical expression of the C-C (macrophage inflammatory protein-1alpha (MIP-1alpha)), monocyte chemotactic protein-1 (MCP-1), and RANTES) and C-X-C (interferon-inducible protein-10 (IP-10), MIP-2, and cytokine-induced neutrophil chemoattractant (CINC)) chemokines 4, 6, 8, 10, 14, and 21 days after the induction of puromycin aminonucleoside (PAN) nephrosis. There was a 7- to 10-fold increase in the steady state mRNA expression of IP-10 and MCP-1 in the renal cortex of rats 6 to 8 days after the administration of PAN that declines thereafter reaching control values by day 21. The site of IP-10 and MCP-1 mRNA production was localized to intrinsic tubulointerstitial cells and not to infiltrating monocytes or macrophages. By comparison, there was a low basal expression of RANTES mRNA in the renal cortex of nephrotic rats that did not differ from those of control rats. In contrast, CINC, MIP-2, and MIP-1alpha mRNAs were not detected. Translation of MCP-1 mRNA into protein was confirmed with an ELISA. These changes in chemokine gene expression were associated with a tubulointerstitial T lymphocyte and macrophage infiltration beginning on day 6 that peaked on day 10. Administration of a neutralizing Ab to rat MCP-1 (n = 5) beginning on day 4 resulted in a 45% decline in tubulointerstitial macrophage infiltration from 8.4 +/- 1.3% to 4.6 +/- 0.4% (p &lt; 0.001) on day 6. These data provide evidence that MCP-1, and possibly IP-10, are important in the pathogenesis of monocyte/macrophage infiltration in the tubulointerstitial nephritis associated with PAN nephrosis.
Stimulation of Fc gamma receptors in rat peritoneal macrophages induces the expression of nitric oxide synthase and chemokines by mechanisms showing different sensitivities to antioxidants and nitric oxide donors.
Authors: Bayón Y , Alonso A , Sánchez Crespo M 
Published: January 2023

Abstract
The induction of nitric oxide (NO) production and the expression of cytokine-induced neutrophil chemoattractant (CINC-1) were studied in rat peritoneal adherent cells stimulated with insoluble immune complexes containing rabbit IgG Ab and OVA as the cognate Ag (IC). Incubation with IC at concentrations as low as 10 microg/ml induced NO production and the expression of inducible NO synthase (iNOS) protein. This was accompanied by the expression of CINC-1 mRNA and the activation of nuclear factor-kappaB (NF-kappaB). However, the expression of iNOS and CINC-1 mRNA induced by IC showed a different temporal pattern and a different sensitivity to both the antioxidant agent pyrrolidine dithiocarbamate (PDTC) and modulation by NO itself. Whereas iNOS mRNA and protein expression were blunted by PDTC and NO-generating compounds, CINC-1 mRNA expression was either enhanced or not affected by PDTC and NO donors. The time course of NF-kappaB activation was parallel to that of iNOS induction and was influenced in the same sense as iNOS induction by antioxidants, NO donors, the protease inhibitor N-tosyl phenylalanine chloromethyl ketone, and inhibitors of protein tyrosine phosphorylation reactions. These data indicate the existence in rat macrophages of a signaling mechanism triggered by Fc gammaR occupancy that leads to nuclear signaling, is initiated by protein tyrosine phosphorylation reactions, and shows specific sensitivities to antioxidants and NO. Whereas trans-activation of the iNOS gene can be fully explained by the stimulation of NF-kappaB, induction of CINC-1 mRNA expression seems influenced by additional regulatory elements.
Binding of human peripheral blood polymorphonuclear leukocytes to E-selectin (CD62E) does not promote their activation.
Authors: Repo H , Rochon Y P , Schwartz B R , Sharar S R , Winn R K , Harlan J M 
Published: January 2023

Abstract
E-selectin (CD62E) is a cytokine-inducible endothelial cell adhesion molecule that tethers polymorphonuclear leukocytes (PMNs) and supports PMN rolling under conditions of flow. We examined whether interaction of PMNs with E-selectin also leads to activation of CD11b/CD18 (Mac-1, alphaMbeta2), an event that can promote firm adhesion. PMNs were added to monolayers of IL-1beta-activated HUVECs and Chinese hamster ovary (CHO) cells transfected with E-selectin cDNA. PMN activation was assessed by 1) increased CD11b/CD18 surface expression, 2) appearance of activation epitope on CD11b/CD18 (CD11b*) detected by mAb CBRM1/5, and 3) decreased L-selectin (CD62L) expression, as determined by flow cytometry. Both adherent and nonadherent supernatant PMNs became activated on IL-1beta-pretreated HUVECs. This activation was not affected by CD62E-blocking mAb P6E2. The activation state of PMNs adhered to CHO cells transfected with E-selectin cDNA was not increased over background and was similar to that of PMNs exposed to parent CHO cells. The findings were confirmed using confocal microscopy, which allowed staining of the cells for CD11b* in situ. In concert, the results suggest that PMN binding to E-selectin does not elicit inter-receptor signaling that could result in strengthening of PMN adhesion to endothelium.
Ligation of L-selectin through conserved regions within the lectin domain activates signal transduction pathways and integrin function in human, mouse, and rat leukocytes.
Authors: Steeber D A , Engel P , Miller A S , Sheetz M P , Tedder T F 
Published: January 2023

Abstract
L-selectin is a cell surface adhesion receptor that mediates leukocyte rolling along vascular endothelium at sites of inflammation and lymphocyte attachment to endothelial cells within peripheral lymphoid tissues. Since ligation of L-selectin through its ligand recognition region may mimic physiologic ligand binding, a new panel of mAbs that engaged a conserved ligand-binding region within the lectin domains of human, mouse, and rat L-selectin were generated using L-selectin-deficient mice. Indeed, appropriate ligation of L-selectin generated transmembrane signals that resulted in immediate intercellular adhesion following cell-cell contact of lymphocytes, neutrophils, and L-selectin cDNA-transfected cells. Ab binding to only some epitopes within the lectin domain of L-selectin induced adhesion, while mAb binding to numerous other epitopes or other domains of L-selectin had no effect. PPME (yeast polyphosphomonoester core polysaccharide), a complex carbohydrate that mimics the natural L-selectin ligand, also induced potent intercellular adhesion. The induction of intercellular adhesion required cellular energy, an intact cytoskeleton, and cytoplasmic kinase activity as well as the membrane proximal and cytoplasmic domains of L-selectin. Therefore, ligation of L-selectin through specific ligand-binding epitopes identified by the mAbs generated in this study can generate transmembrane signals. Signaling through L-selectin may enhance leukocyte-endothelial cell interactions by serving as an activation/priming step during rolling, thereby promoting subsequent firm cell-cell adhesion in the presence of inflammatory mediators.
Increased susceptibility to endotoxin shock in complement C3- and C4-deficient mice is corrected by C1 inhibitor replacement.
Authors: Fischer M B , Prodeus A P , Nicholson-Weller A , Ma M , Murrow J , Reid R R , Warren H B , Lage A L , Moore F D , Rosen F S , Carroll M C 
Published: January 2023

Abstract
Endotoxin shock is a life-threatening syndrome associated with a Gram-negative infection and mediated by a systemic inflammatory response. As a major effector of inflammation, the complement system has been implicated in both the pathogenesis and the protection from endotoxin shock. To clarify the role of complement in endotoxin shock, we have used mice totally deficient in either complement component C3 or C4. We found that both the C3- and C4-deficient mice were significantly more sensitive to endotoxin than wild-type controls. The endotoxin-challenged complement-deficient mice failed to clear endotoxin efficiently from the circulation and this led to excess consumption of C1 inhibitor protein (C1 INH), a major regulator of both complement and the contact system of blood coagulation. Replacement of C1 INH rescued the endotoxin-challenged complement-deficient mice from shock and death. These findings suggest a novel therapy for treatment of endotoxemia with C1 INH protein.