bluuebunny/crossref_metadata_2025_split huggingface dataset:
Murine C4b-binding protein. Mapping of the ligand binding site and the N-terminus of the pre-protein.
Authors: Ogata R T , Mathias P , Bradt B M , Cooper N R 
Published: December 2022

Abstract
We have constructed cell surface-bound forms of murine C4b-binding protein (mC4BP) that allowed us to monitor the binding of mC4BP to C4b with relatively simple erythrocyte rosette assays. We used two types of surface-bound mC4BP: one in which segments of mC4BP were fused directly to a peptide containing the transmembrane and cytoplasmic domains of human complement receptor CR2 (BPR1-type); and a second in which the same segments were fused to a longer peptide containing the five membrane-proximal short consensus repeats (SCR) of CR2 as well as the transmembrane and cytoplasmic domains (BPR2-type). COS cells transfected with either construct carrying all six mC4BP SCR rosetted with C4b-bearing EAC14 cells but not with C4b-lacking EAC1 cells; and rosetting was inhibited by excess inactivated C4 but not inactivated C3. COS cells transfected with BPR2 constructs carrying only SCR 1-3 or 1-4 gave similar rosetting behavior. However, rosetting was not observed with BPR2 constructs carrying only SCR 1-2 or 2-6, or with BPR1 constructs carrying only SCR 1-2, 1-3, 1-4, or 2-6. Finally, we found that alteration of the AUG sequence 56 triplet codons upstream of the putative N-terminus of mature mC4-BP eliminates rosetting whereas alteration of a second AUG sequence 13 codons upstream has no effect on rosetting. These results indicate that 1) SCR 1-3 of mC4BP are necessary and adequate for binding to C4b, 2) steric effects close to the cell surface may interfere with binding, and 3) mC4BP has an extraordinarily long 56 amino acid residue signal peptide.
Pure protein from Leishmania donovani protects mice against both cutaneous and visceral leishmaniasis.
Authors: Rachamim N , Jaffe C L 
Published: December 2022

Abstract
A protein purified from Leishmania donovani promastigotes, dp72, was shown to partially protect BALB/c mice against a challenge by this parasite. Immunized mice infected i.v. with 10(7) L. donovani promastigotes showed a 0, 60, and 78% reduction in liver parasite burden compared with the control mice at each time point examined after challenge, 1, 20, and 108 days, respectively. Western blotting demonstrated that the sera from the immune mice, which reacted specifically with dp72 in lysates of L. donovani, cross-reacted with one major band in total homogenates of Leishmania major and Leptomonas collosoma. Lymphocyte proliferation to crude and pure parasite Ag was also examined in mice immunized with dp72. Strong proliferation was found at low concentrations of crude L. donovani Ag (0.5 micrograms/ml) and with pure dp72. Proliferation at higher concentrations to crude L. major and L. collosoma Ag was observed. Little or no reaction (stimulation index &lt; 1.0) was seen with other pure leishmanial Ag, including gp70-2, the promastigote surface protease, and lipophosphoglycan. Depletion in vitro of the CD4+ T cell subset from immune spleen cells abolished proliferation to dp72, whereas depletion of CD8+ T cells enhanced proliferation to the pure Ag. Experiments in vivo showed that immunized mice treated with antibodies to either CD4+, CD8+, both T cell subsets, or to IFN-gamma had larger LPB (178, 173, 176, and 130%, respectively) after challenge with L. donovani than nonimmunized controls. Mice immunized with dp72 but treated with either PBS or mouse Ig showed reduced LPB, 81 and 61%, respectively, compared with the nonimmunized animals. BALB/c mice immunized with dp72 were also protected against L. major which causes cutaneous leishmaniasis. Immunized mice infected with either 10(4) or 10(6) promastigotes did not develop lesions. Limiting dilution assays confirmed the protection.
Granulocyte-macrophage-colony-stimulating factor differentially regulates neutrophil migration across IL-1-activated and nonactivated human endothelium.
Authors: Yong K L , Linch D C 
Published: December 2022

Abstract
The directed migration of neutrophils across vascular endothelium to localize in inflammatory tissues is controlled by soluble mediators, including cytokines and growth factors. Granulocyte-macrophage CSF (GM-CSF) enhances and primes neutrophil functions, but its specific role in the movement and localization of neutrophils to infective sites has not been clarified. We demonstrate, using an in vitro model of the vascular endothelial barrier, that GM-CSF enhances neutrophil migration across unstimulated endothelium, increasing the percentage of migrating cells from 7.7 +/- 0.9% (mean +/- SE) in controls to 12.5 +/- 1.5% in the presence of GM-CSF (100 ng/ml) (n = 14, p &lt; 0.0005). This effect is dose dependent, with maximal effects achieved at concentrations of 10 ng/ml or greater, and is independent of concentration gradients of GM-CSF. Transendothelial migration of neutrophils can also be increased by cytokine treatment of the endothelial cells. Preincubation of endothelial monolayers with IL-1 (10 U/ml) for 4 h increases the percentage of migrating cells to 16.8 +/- 1.4% (238 +/- 25% of base line, n = 7, p &lt; 0.005). In the presence of GM-CSF, however, neutrophil migration across IL-1 treated endothelium (12.5 +/- 1.6%, n = 7) is no different from that across resting endothelium (11.6 +/- 1.6% in the same seven experiments). Hence GM-CSF acts to inhibit neutrophil migration across IL-1-activated endothelium, and almost completely abolishes IL-1-induced migration (n = 7, p &lt; 0.0005). This differential effect of GM-CSF on neutrophil migration, depending upon the conditions of endothelial activation, does not relate to an effect on adhesion, because GM-CSF has no effect on the increased adhesion of neutrophils to IL-1-treated endothelium. The effect of GM-CSF on neutrophil migration across activated endothelium may be relevant to the clinical administration of human rGM-CSF.
Defects in the differentiation and function of antigen presenting cells in NOD/Lt mice.
Authors: Serreze D V , Gaskins H R , Leiter E H 
Published: December 2022

Abstract
Although T lymphocytes are the ultimate effectors of pancreatic beta cell destruction in autoimmune insulin-dependent diabetes, previous work has established that beta cell autoreactive T cells are generated in nonobese diabetic (NOD) mice as a result of APC dysfunctions. To determine if APC dysfunctions could result from developmental defects, we analyzed if macrophages (M phi) develop normally from NOD bone marrow stimulated with CSF-1 in the presence and absence of IFN-gamma. Due to interactions between the diabetogenic H-2g7 haplotype and background modifiers, NOD bone marrow cells were found to proliferate poorly to CSF-1 stimulation. IFN-gamma aberrantly increased CSF-1-stimulated proliferation of H-2g7 expressing bone marrow cells, although decreasing proliferation of bone marrow cells expressing diabetes resistant MHC haplotypes. FACS analysis indicated the diminished sensitivity of NOD hematopoietic precursors to CSF-1 was associated with a quantitative inability to generate phenotypically mature M phi. In addition to developmental defects, NOD M phi were also found to be functionally defective. Total MHC class I expression was aberrantly down-regulated in a tissue specific fashion in IFN-gamma-treated M phi from NOD mice, whereas MHC class I expression increased as expected in M phi from C57BL/KsJ (BKs) control mice. Total MHC class I expression also increased in IFN-gamma-treated M phi from NOR mice, a diabetes-resistant control strain that shares the H-2g7 haplotype of NOD, but contains BKs-derived genomic elements on chromosomes 2, 4, 11, and 12. This demonstrates differential trans-regulation of class I loci within the diabetogenic H-2g7 haplotype in NOD vs diabetes-resistant NOR mice. Aberrant down-regulation of MHC class I content in IFN-gamma-treated M phi from NOD mice was associated with decreased ability to activate CTL function. We propose these defects in M phi differentiation and function may interact with H-2g7 to generate APC in NOD mice that are unable to activate tolerogenic mechanisms, but remain capable of activating low level effector responses.
Manifestation of the MHC-unrestricted killing potential of a cytotoxic T cell clone requires activation in response to MHC-restricted self-presentation of antigen.
Authors: Dick T , Staege M S , Reichmann G , Reske-Kunz A B 
Published: December 2022

Abstract
10BK.1 T clone cells of (B10 x B10.BR)F1 genotype specifically react to peptides of OVA, frequently encountered in OVA preparations, and to the synthetic peptide OVA257-264 in an H-2Kb-restricted manner; the T clone cells produce lymphokines and proliferate in the absence of added APC, suggesting self-presentation of the Ag by the T cells. In accordance with their CD8+ CD4- phenotype 10BK.1 cells exhibit cytotoxic capacity. When the target cells were pretreated with OVA257-264 only cells bearing H-2Kb molecules were lysed. However, when the relevant OVA peptide was present during the 4-h 51Cr release assay 10BK.1 cells lysed target cells expressing H-2Kb molecules as well as target cells lacking H-2Kb elements. Likewise, 10BK.1 cells pretreated with OVA257-264 for 1 h and washed extensively to remove residual Ag were able to kill syngeneic and allogeneic target cells. Killing of allogeneic targets in the presence of Ag was inhibited by antibodies directed at H-2Kb. Allogeneic target cells were not killed when 10BK.1 cells were stimulated by peptide-pulsed syngeneic cells. Triggering of the TCR/CD3 complex of 10BK.1 cells was involved during the activation phase but not during the lytic phase. IL-2 did not participate in the MHC-unrestricted killing event. To explain the observed MHC-unrestricted cytotoxicity of 10BK.1 cells, the following model is proposed. In an initial step 10BK.1 cells present the relevant OVA peptide to one another in a H-2Kb-restricted fashion. The cells are thereby triggered to mobilize the lytic machinery. In a second step sensitized 10BK.1 cells lyse allogeneic target cells. Thus, the MHC-unrestricted cytotoxicity can be dissected into an MHC-restricted phase of 10BK.1 cell activation and an MHC-unrestricted lytic phase. Cytotoxic T cells with Ag self-presentation functions may account for tissue damage during bacterial infections.
The B cell immune response to an idiotype-inducing peptide epitope can be inhibited by immunodominance of a neighboring epitope.
Authors: Ju S T , Nonogaki T , Bernatowicz M S , Matsueda G R 
Published: December 2022

Abstract
Three synthetic peptides, EEYEYE (peptide 1), EEYEYEEEYEYE (peptide 2), and YEEEEY (peptide 3), were tested for their ability to induce common Id that had been previously characterized for murine antibodies specific to random synthetic polymers of glutamic acid, alanine, and tyrosine ((Glu,Ala,Tyr)n) (cGAT Id). Protein conjugates of either peptide 2 or peptide 3, but not peptide 1, induced cGAT Id. This unique approach directly identified two peptides capable of inducing cGAT Id antibodies. Previous immunization with peptide 1-protein conjugate inhibited the cGAT Id response to peptide 2 conjugated to a different protein carrier. Thus, a neighboring or overlapping epitope can be used to inhibit a cGAT Id-inducing epitope without the participation of carrier-specific Ts and without using anti-Id antibodies. In contrast, previous immunization with peptide 1-protein conjugate did not inhibit cGAT Id induction by peptide 3-protein conjugate or by (Glu,Ala,Tyr)n. This ruled out the participation of Id-specific Ts cells. The effectiveness of inhibition coincided with the avid binding of anti-peptide 1 antibodies to peptide 2, which was &gt; 10 and 100 times stronger than the binding to peptide 3 and (Glu,Ala,Tyr)n, respectively. We hypothesize that the primed peptide 1-specific B cells capture and process peptide 2-protein efficiently and act as APC to Th cells specific to the protein of the challenging Ag, resulting in the selective and dominant activation of peptide 1-specific B cells. Thus, our data suggest that epitope priming can inhibit an Id response to a neighboring epitope by a mechanism of clonal dominance.
Induction of functional follicular dendritic cell development in severe combined immunodeficiency mice. Influence of B and T cells.
Authors: Kapasi Z F , Burton G F , Shultz L D , Tew J G , Szakal A K 
Published: December 2022

Abstract
Ag injected into immune mice immediately complexes with specific antibody. Immune complexes not phagocytosed by macrophages are transported by Ag transport cells to lymph node follicles for trapping by follicular dendritic cells (FDC). These FDC serve as a long term repository of unprocessed Ag that is believed to maintain both B cell memory and the secondary antibody response. Severe combined immunodeficiency mice lack functional B cells and T cells. Consequently, this mutation also appears to affect the ability to produce Ag-retaining FDC. to assess B and T cell requirements for FDC development and function, severe combined immunodeficiency mice were reconstituted with BM, or mature B and T cells. The development of a FDC reticulum, a three-dimensional network produced by the intertwining of FDC dendrites was assessed by Ag trapping on FDC using the histochemically detectable Ag horseradish peroxidase and quantitated by morphometry. The results showed that bone marrow transplants or B and T cells transferred together supply the required elements for the development of severe combined immunodeficiency FDC reticula that function in Ag trapping and the induction of the germinal center. In contrast, B cells or T cells injected separately induced a minimal development of FDC reticulum. The B and T cell requirements demonstrated here strongly indicate that B-T cell collaboration and the factors these cells produce are essential for FDC development.
Antigen entry into early endosomes is insufficient for MHC class II processing.
Authors: Niebling W L , Pierce S K 
Published: December 2022

Abstract
Helper T-cell recognition of Ag requires that the Ag be processed and presented by class II-expressing Ag-presenting cells. Processing involves the introduction of Ag into acidic compartments where proteolysis occurs producing peptides that bind to the class II molecules. Although Ag can enter the processing pathway through fluid phase pinocytosis, Ag processing can be made over 1000-fold more efficient by binding the Ag to a variety of Ag-presenting cell surface structures. The increased efficiency in processing is presumably the result of the ability of such structures to deliver the bound Ag to compartments involved in processing. Here we report that Ag bound to the transferrin receptor (TfR), which cycles predominantly through early endosomal compartments, does not enter the processing pathway. We found that cytochrome c(c)covalently coupled to monovalent iron-saturated transferrin (Tf), (c-Tf), is not processed or presented significantly better than unconjugated c, indicating that the majority of cycling TfR does not enter compartments where processing proceeds. The conjugation of Tf to c does not affect its binding to the TfR, as the binding is both saturable and compatible with unmodified Tf. Moreover, c-Tf and unmodified Tf cycle equivalently with a t1/2 of internalization of 3 to 5 min and are released outside the cell with little detectable degradation. Significantly, we found that c-Tf is efficiently processed and presented when the TfR is cross-linked, altering its normal cycling. Indeed, c covalently coupled to polymerized Tf is presented at 1/100th the concentration of c alone. Cross-linking of c-Tf bound to the TfR using c-specific antibodies also results in efficient processing and presentation. Thus, the endosomal compartments through which Tf normally cycles are not sites of processing, whereas compartments into which cross-linked Tf is diverted allow efficient processing and presentation of Ag.
Comparative in vitro analysis of proliferation, Ig secretion, and Ig class switching by murine marginal zone and follicular B cells.
Authors: Snapper C M , Yamada H , Smoot D , Sneed R , Lees A , Mond J J 
Published: December 2022

Abstract
We have previously demonstrated that activation of murine B cells by dextran-conjugated anti-IgD antibodies may serve as a polyclonal, in vitro model system for studying immune responses to T cell-independent type 2 (TI-2) Ag, as exemplified by the bacterial polysaccharides. Because in vivo Ig responses to TI-2 Ag are mediated primarily by B cells resident in the splenic marginal zone, we wished to determine whether this reflected an intrinsic difference in the responsiveness of marginal zone B cells (MZB) compared with follicular B cells (FB) to this class of Ag. In this report we demonstrate that highly purified MZB, isolated by electronic cell sorting, exhibit a lower proliferative response in vitro in response to unconjugated anti-Ig antibody as well as to dextran- or Sepharose-conjugated anti-IgM or anti-IgD antibodies, whereas they proliferate equal to or better than FB when stimulated by other B cell mitogens including LPS, Salmonella typhimurium mitogen, or anti-CD3-activated CD4+ Th2 cell clone. Despite the different proliferative responses of MZB and FB induced by anti-Ig, Ag receptor cross-linkage stimulates comparable increases in intracellular free calcium concentrations in both of these B cell populations. Furthermore, MZB secrete Ig and undergo Ig isotype switching to a comparable degree, relative to FB, in response to both T cell-dependent and T cell-independent stimuli. This suggests that the compartmentalization of TI-2 responses to the splenic marginal zone rather than the follicular zone reflects something other than the intrinsic responsiveness of the B cells from these two sites.
The gamma subunit of the B cell antigen-receptor complex is a C-terminally truncated product of the B29 gene.
Authors: Friedrich R J , Campbell K S , Cambier J C 
Published: December 2022

Abstract
The predominant Ag-receptor complex of B cells consists of mIgM or mIgD noncovalently associated with glycosylated heterodimers of Ig-alpha and Ig-beta or Ig-alpha and Ig-gamma. Upon B cell stimulation the associated proteins are phosphorylated, giving rise to pp32/33 (alpha), pp37 (beta), and pp34 (previously designated gamma). Ig-alpha and Ig-beta contain extended cytoplasmic structure (61 and 48 amino acids, respectively) and associate with cytoplasmic effectors indicating that they are directly involved in signal transduction. Here we report analysis of the structural relationship of mIgM- and mIgD-associated Ig-beta and Ig-gamma chains from mice. N-terminal sequence, immunoblotting, and physicochemical analyses show that both Ig-beta and Ig-gamma are products of the B cell-specific B29 gene and demonstrate that the 37-kDa Ig-beta protein is the full length predicted product of the B29 gene. The Ig-associated protein that migrates in the 34-kDa range is actually two distinct species. The minor species is a phosphorylatable and underglycosylated form of full length Ig-beta, and the major species is a C-terminally truncated form of B29, which we now designate Ig-gamma. This conclusion is based on the observations that Ig-gamma is composed of a core protein which is 3 to 4 kDa smaller than deglycosylated Ig-beta, it is not phosphorylated, unlike Ig-beta, and it does not react with an antiserum raised against a peptide of the seven C-terminal amino acids of B29. Based on these findings we estimate that Ig-gamma is truncated by about 30 to 36 amino acid residues and hypothesize that the most 3' B29 exon, which encodes the 32 C-terminal residues, may not be expressed in Ig-gamma. All of the documented B29 products are found in association with both mIgM and mIgD. Interestingly, Ig-gamma is found in intermediate and low density splenic B cells, but is not detectable in resting B cells. This raises the possibility that it may confer some distinct signaling function on the Ag receptors of these cells.
Characterization of the alpha subunit of the IFN-alpha receptor. Evidence of N- and O-linked glycosylation and association with other surface proteins.
Authors: Platanias L C , Pfeffer L M , Cruciani R , Colamonici O R 
Published: December 2022

Abstract
We studied the association of the alpha subunit of the (IFN-alpha-receptor) to other receptor components in the human H-929 and U-266 myeloma cell lines. Immunoprecipitation performed with the IFNaR3 mAb showed that two proteins with molecular masses of 205 and 145 kDa are co-precipitated with the alpha subunit. These complexes may not bind IFN-alpha as shown by studies using the heterobifunctional cross-linking reagent Denny-Jaffe and by partial cleavage of the homobifunctional cross-linker dithio succinimidyl propionate. These studies also provided evidence that at least two subunits with molecular mass of 130 kDa (alpha subunit) and 110 kDa (including 20 kDa corresponding to IFN-alpha) contribute to the formation of the IFN-alpha-receptor complex. To further characterize the alpha subunit of the IFN-alpha-receptor, immunoprecipitates using the mAb IFNaR3 were sequentially treated with N-glycanase, neuraminidase and O-glycanase. These studies showed that the alpha subunit is heavily glycosylated and has a protein precursor with a molecular mass of 68 kDa. Binding studies provided evidence for high and low affinity binding sites for IFN-alpha 2. Affinity cross-linking experiments under low and high affinity conditions suggest that the high affinity binding site of the IFN-alpha-receptor is formed by a complex containing the alpha subunit, whereas the 110-kDa subunit may bind IFN-alpha 2 under low affinity conditions.
Effects of cytokines on multiplication of Toxoplasma gondii in microglial cells.
Authors: Chao C C , Hu S , Gekker G , Novick W J , Remington J S , Peterson P K 
Published: December 2022

Abstract
Microglia may play a role in host defense against Toxoplasma gondii in the central nervous system. In our study, the antitoxoplasma activity of murine microglia was investigated. T. gondii multiplied readily in cultured microglial cells, and activation of these cells with IFN-gamma plus LPS suppressed (p &lt; 0.01) intracellular growth of this parasite. This antitoxoplasma defense of activated microglia was significantly blocked by neutralizing antibodies against TNF-alpha and transforming growth factor-beta, suggesting that these cytokines play a role in the inhibitory process. Consistent with this hypothesis, activation of microglia with IFN-gamma plus TNF-alpha or transforming growth factor-beta inhibited, in a dose-dependent manner, T. gondii multiplication. Treatment with pentoxifylline or dexamethasone, drugs that suppress production of TNF-alpha, prevented (p &lt; 0.01) the microglia from exerting an anti-T. gondii effect. These findings suggest that the host defense function of microglia against T. gondii is dependent primarily on the activating properties of IFN-gamma and TNF-alpha, and that agents that interfere with cytokine-mediated activation may promote the pathogenesis of this infection.