bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of C gamma subclass germ-line transcripts in human peripheral blood B cells.
Authors: Kitani A , Strober W 
Published: December 2022

Abstract
In the present study we investigated the early steps of human IgG subclass differentiation by defining the conditions necessary for IgG subclass-specific production of germ-line transcripts in human peripheral blood B cells. Constant region of gamma-globulin (C gamma) subclass germ-line transcripts were measured using newly developed reverse transcription and polymerase chain reaction (RT-PCR) assays that were shown to be C gamma subclass-specific germ-line transcripts by size of the amplification products obtained before and after digestion with appropriate endonucleases (NarI and NcoI). In initial studies we found that C gamma 1 and C gamma 2 germ-line transcripts were constitutively expressed in total peripheral blood B cells, but not in high density sIgM+(sIgG-) B cells prepared with Percoll density gradients and magnetic beads separation techniques; the latter cells were therefore used throughout this study. Induction of germ-line transcripts (germ-line C gamma 1 transcript) was noted in stimulated B cells (SAC plus IL-2) at 6 h; thus, the appearance of germ-line transcripts could not be attributed to preferential growth of B cells expressing germ-line transcripts. In subsequent studies we found that induction of germ-line transcripts for the various IgG subclasses fell into two patterns. Induction of C gamma 3 and C gamma 1 germ-line transcripts, transcripts of genes in the first human duplication unit, generally required a proliferative stimulus (Staphylococcus aureus Cowan I, SAC) and was brought about by SAC plus IL-4 (C gamma 3 germ-line transcripts) and SAC alone or SAC plus IL-2 (C gamma 1 germ-line transcripts); in contrast, induction of C gamma 2 and C gamma 4 germ-line transcripts, transcripts of genes in the second duplication unit, was accomplished with cytokines alone: IFN-gamma (C gamma 2 germ-line transcripts) and IL-4 (C gamma 4 germ-line transcripts), and was not augmented by addition of a proliferative stimulus. Finally, we found that IFN-gamma inhibited IL-4-induced C gamma 3 and C gamma 4 germ-line transcripts (with or without SAC). These findings establish that the various human IgG subclasses manifest distinct requirements for the regulation of early steps in isotype differentiation. In addition, they suggest that human C gamma genes exhibit patterns of regulation related to their respective duplication units.
Functional and phenotypic analysis of thymocytes in SCID mice. Evidence for functional response transitions before and after the SCID arrest point.
Authors: Rothenberg E V , Chen D , Diamond R A 
Published: December 2022

Abstract
Thymocytes from severe combined immune deficient (SCID) mice undergo developmental arrest at an early stage, before most TCR gene rearrangement. They therefore represent a natural test case to assess those aspects of T cell development that are TCR independent. Multiparameter flow cytometry was used to analyze the array of immature phenotypes present in the SCID thymus at steady state, as defined by the markers CD4, CD5, Sca-1, NK1.1, CD44, heat-stable antigen (HSA), and IL-2R alpha. The results suggest a simple developmental block in SCID mice rather than a program of aberrant differentiation. SCID thymocytes displayed efficient, developmentally regulated functional responses. Approximately 20-25% of the cells, mostly within the IL-2R alpha +HSA+CD44low fraction, could be induced to express IL-2. This IL-2 inducibility was highly dependent on IL-1 costimulation, in agreement with the behavior of normal immature thymocytes. These results formally demonstrate that competence to express IL-2 is developed independently of TCR expression or gene rearrangement. Comparison of the response properties of various SCID thymocyte subsets indicated that IL-2 inducibility is first likely to be acquired at an early (Sca-1++CD44++HSAlow) stage. A later functional transition was revealed by comparing patterns of IL-2R alpha regulation in normal and SCID IL-2R alpha +HSA+CD44low thymocytes. The SCID thymocytes uniformly maintained IL-2R alpha expression on in vitro stimulation, whereas only a minority of the normal cells in the corresponding subset could do so unless IL-1 was also added. The SCID arrest point thus appears to separate the IL-2R alpha +HSA+CD44low stage into distinct early (TCR independent) and late phases. Normal cells that progress beyond the SCID arrest point appear to lose, rather than gain, competence to make various responses, even before they leave the IL-2R alpha +HSA+CD44low stage. A model is proposed in which discrete changes in functional competence define novel transitions in early thymocyte development, at least some of which may be linked to TCR-beta gene rearrangement before positive or negative selection.
Probing the human receptor for C5a anaphylatoxin with site-directed antibodies. Identification of a potential ligand binding site on the NH2-terminal domain.
Authors: Oppermann M , Raedt U , Hebell T , Schmidt B , Zimmermann B , Götze O 
Published: December 2022

Abstract
Molecular cloning has revealed the DNA sequence of the human receptor for the C5a anaphylatoxin (C5aR). In this study, mAb and polyclonal antibodies with specificities for deduced hydrophilic sequences of the receptor protein were employed to determine the expression and the topography of C5aR on PBL. Evidence was obtained that an antigenically homogenous receptor exists on human neutrophils, eosinophils, and monocytes that binds C5a and C5a(desArg). The assignment of epitopes to extra- or intracellular receptor domains as determined by FACS analysis of intact or permeabilized cells confirmed the general topography of the C5aR that had been predicted by hydropathy analysis. Competitive binding studies were performed to examine whether extracellular receptor domains participate in ligand binding. The occupation of the receptor by C5a inhibited only the binding of antibodies that were specific for the receptor's aminoterminal domain (C5aR-EX1). The anti-EX1 mAb S5/1 effectively antagonized C5a/C5a(desArg) biological activity. A heptameric peptide (D15DKDTLD21) was identified as the smallest receptor fragment that was recognized by the mAb S5/1 or by polyclonal rabbit anti-EX1 lg. These results imply that an amino acid sequence rich in aspartate within the receptor aminoterminus represents both an immunodominant epitope and a ligand binding site on the C5aR.
Peptide-induced changes in class I heavy chains alter allorecognition.
Authors: Bluestone J A , Kaliyaperumal A , Jameson S , Miller S , Dick R 
Published: December 2022

Abstract
Class I molecules of the MHC are intimately involved in the development and function of CD8+ T cells. Small peptides, derived from endogenous proteins, bind within the Ag binding groove created by the beta-pleated sheets and alpha-helices of the alpha 1 and alpha 2 domains of the class I molecule. This peptide-MHC complex has been shown to influence allorecognition by CD8+ T cells. However, the precise role of peptide in alloantigen recognition remains unclear. We have previously shown that conformational changes induced in the class I molecules can be identified as specific alterations in serologic epitopes. These results suggested that alloreactive T cells may detect structural changes in MHC based on the nature of the peptide binding to the class I protein. Here, we have shown that, in at least some instances, alloreactivity may not depend on the recognition of a precise self-peptide but on an epitope on the class I molecule influenced by the peptide. The nature of specific peptides expressed by class I-bearing cells may, therefore, have a dramatic effect on T cell development, self-tolerance, and alloreactivity.
Multiple pathways are involved in the extracellular processing of MHC class I-restricted peptides.
Authors: Kozlowski S , Corr M , Shirai M , Boyd L F , Pendleton C D , Berzofsky J A , Margulies D H 
Published: December 2022

Abstract
T cell stimulation by certain class I-restricted antigenic peptides, such as the HIV 1 gp160-derived peptide, P18, requires peptide processing by angiotensin-1 converting enzyme (ACE) in FCS. We observed that longer versions of P18 and the murine cytomegalovirus pp89-derived core peptide, pMCMV, which could stimulate T cell hybridomas in FCS, were not as sensitive to the ACE inhibitor captopril as P18. Using cell-free soluble murine class I MHC molecules and protease inhibitors, we found that there are pathways of differing efficiency that use enzymes other than ACE for the proteolytic processing of peptides in serum. The kinetics of the generation of T cell stimulatory activity among P18 variant peptides in serum differed with peptide length, and with the nature of amino and COOH-terminal extensions. Such processing occurs in human plasma as well as in FCS. The understanding of this processing, its kinetics, and its inhibitors can lead to better design of peptide-based therapies, including vaccines.
The TAPA-1 molecule is associated on the surface of B cells with HLA-DR molecules.
Authors: Schick M R , Levy S 
Published: December 2022

Abstract
TAPA-1 is a transmembrane protein that has been shown to be involved in cell growth and cellular adhesion. Our studies were aimed at determining the mechanisms of the biologic phenomena mediated by TAPA-1, which include the identification of proteins that are associated with it on the surface of lymphocytes. We and others have previously shown that Leu-13, a leukocyte Ag, is one such molecule and that in B cells TAPA-1 is associated with the CD19 Ag. Herein we identify an additional molecule, HLA-DR, that is noncovalently associated on the surface of B cells with TAPA-1. This association was first detected by immunoprecipitation by anti-TAPA-1 and by anti-HLA-DR antibodies in the presence of mild detergents. The initial observation was confirmed by 2-dimensional SDS-PAGE and by direct identification of TAPA-1 in anti-HLA-DR immunoprecipitates by Western blot analysis. The association of the two molecules on the surface of a human B cell line was shown by cocapping experiments. In addition, antibodies to both molecules can induce cellular adhesion and an antiproliferative effect. Because the tissue distribution of these two molecules only partially overlaps, with TAPA-1 being expressed on most cell types and MHC class II expressed on a more restricted group of tissue, it is possible that the TAPA-1 molecule provides a basic function that can augment a cell type specific activity. In B cells the association of TAPA-1 with CD19 and HLA-DR may increase cellular interaction and play a supporting role in the transmission of specific signals.
Distinct divalent cation requirements for integrin-mediated CD4+ T lymphocyte adhesion to ICAM-1, fibronectin, VCAM-1, and invasin.
Authors: Shimizu Y , Mobley J L 
Published: December 2022

Abstract
Integrins are a large family of cell surface receptors that mediate the adhesion of cells to other cells and to components of the extracellular matrix. Various divalent cations, particularly Ca2+ and Mn2+, have been shown to modulate the functional activity of many different integrins expressed on a wide variety of cell types. In this study, we have characterized the divalent cation requirements for the adhesion of human peripheral CD4+ T cells to four distinct integrin ligands: the alpha 4 beta 1 and alpha 5 beta 1 ligand fibronectin, the alpha 4 beta 1 ligand VCAM-1, the LFA-1 ligand ICAM-1, and the alpha 4 beta 1 bacterial ligand invasin. We find that there are distinct divalent cation requirements for T cell adhesion to each of these ligands: 1) Mg2+/EGTA treatment selectively up-regulates T cell adhesion to ICAM-1; 2) Mn2+ coordinately up-regulates adhesion to ICAM-1, fibronectin, and VCAM-1, with a peak response at 100 microM Mn2+; 3) Ca2+ can selectively support adhesion to VCAM-1 induced by activation and inhibit Mn(2+)-dependent adhesion to ICAM-1; and 4) binding to invasin is maximal in the presence of Ca2+, Mg2+, or Mn2+. Furthermore, divalent cation modifications do not fully up-regulate T cell adhesion to fibronectin, VCAM-1, and ICAM-1, because additional cell activation with phorbol ester treatment can further enhance adhesion in the presence of Mn2+. These results suggest that modification of divalent cations may provide a mechanism by which an individual integrin receptor/ligand interaction can be specifically and selectively regulated.
Structural analysis of proteolytic products of MHC class II-invariant chain complexes generated in vivo.
Authors: Newcomb J R , Cresswell P 
Published: December 2022

Abstract
The MHC class II alpha beta heterodimer associates with invariant (I) chain in the endoplasmic reticulum and remains associated until the complex reaches a post-Golgi compartment. During early stages of transport, I chain blocks peptide binding to alpha beta dimers. I chain is proteolytically cleaved in a post-Golgi compartment releasing alpha beta dimers that can bind antigenic peptides and transport them to the cell surface. Human B lymphoblastoid cell lines grown in leupeptin, a sulfhydryl protease inhibitor, accumulate a partial proteolytic product of the I chain called leupeptin-induced protein (LIP). LIP remains associated with alpha beta dimers. We find, using chemical cross-linking, sucrose gradient sedimentation, and size exclusion chromatography, that the alpha beta LIP complex retains the nine-subunit structure described for alpha beta I complexes. Unlike the alpha beta I complex, in certain detergents the alpha beta LIP nonamer is unstable and dissociates into trimers containing one alpha, beta, and LIP molecule. This finding emphasizes the reported stoichiometry of the alpha beta I complex as a nine-subunit structure comprised of three alpha beta I trimers. Also, these data indicate that the region(s) of I chain necessary for retaining the nonameric structure lie within the LIP fragment, but that domains to the C-terminus of the LIP cleavage site act to further stabilize the nine chain structure. In addition, alpha beta I complexes containing forms of human I chain encoding the p35/p43 N-terminal cytoplasmic extension responsible for endoplasmic reticulum retention can transport to post-Golgi proteolytic compartments where LIP is formed.
Monocytes do not make mast cells when cultured in the presence of SCF. Characterization of the circulating mast cell progenitor as a c-kit+, CD34+, Ly-, CD14-, CD17-, colony-forming cell.
Authors: Agis H , Willheim M , Sperr W R , Wilfing A , Krömer E , Kabrna E , Spanblöchl E , Strobl H , Geissler K , Spittler A , Boltz-Nitulescu G , Majdic O , Lechner K , Valent P 
Published: December 2022

Abstract
Mast cells (MC3) belong to the hemopoietic system and arise from hemopoietic precursor cells. Human MC progenitors can be detected in the bone marrow as well as in the peripheral blood (pb) and are responsive to the mast cell growth factor SCF, the ligand of the c-kit tyrosine kinase receptor. However, little is known about the subsets of cells that become committed to and differentiate into mature human MC. In this study, the identity of the circulating MC progenitor, previously felt to be a monocyte (Mo) or basophil (Ba), was investigated. For this purpose, CD14+ pb monocytes, CD17+ pb basophils and CD34+ cord blood cells were purified to homogeneity (&gt; 95%) from mononuclear cells (normal adult donors, n = 17, cord blood, n = 2) by counter-flow centrifugation followed by cell sorting with mAb. In the presence of rhSCF, MC developed in long term suspension culture from pure CD34+ cells but not from pure Mo, pure Ba, or Ly (MC-tryptase levels on day 42: CD14+ Mo: 3.7 +/- 0.8 vs CD17+ Ba: 3.2 +/- 0.5 vs Ly: 2.0 +/- 1.5 vs control: 196.5 +/- 92.5 ng/ml, p &lt; 0.001). Depletion of CD34+ cells from MNC resulted in a loss of MC in long term suspension culture, whereas depletion of either Mo, Ba, or Ly did not. In methyl-cellulose cultures in the presence of rhSCF, MC and tryptase could be detected in pure (CFU-mast) and mixed (CFU-myeloid/mast) MC colonies. Together, MC do not originate from circulating Mo, Ba, or Ly. The circulating MC progenitor is a CD34+, c-kit+, Ly-, CD14-, CD17- colony-forming cell. This is the first definitive demonstration that mast cells are replenished directly from early hemopoietic progenitors and thus form a unique cell lineage within the hemopoietic system.
Differential cytokine regulation of complement C3, C4, and factor B synthesis in human intestinal epithelial cell line, Caco-2.
Authors: Andoh A , Fujiyama Y , Bamba T , Hosoda S 
Published: December 2022

Abstract
In the intestinal tract, the local synthesis of C3 and components of both the classical (C4) and alternative (factor B) C activation pathway has previously been demonstrated in vivo. However, the cellular source of this local C synthesis has not been identified. In this study, we demonstrated the syntheses of C3, C4, and factor B in the human colonic adenocarcinoma cell line Caco-2, which is regarded as a good experimental model of normal human intestinal epithelial cells. The results of metabolic labeling experiments indicated that the intra- and extracellular molecular sizes and subunit structures of Caco-2-derived C3, C4, and factor B were compatible with previously reported values for these components in other cells. The functional activities of C3 and C4 in the supernatants were also demonstrated by hemolytic titration assay. Furthermore, C syntheses in this line were independently upregulated by several human cytokines: C3 synthesis was dose-dependently enhanced by the addition of IL-1 beta or TNF-alpha; C4 synthesis was enhanced by the addition of IL-6 or IFN-gamma in the same manner; and the addition of IL-1 beta or IL-6 also induced a dose-dependent increase in factor B synthesis. These enhancing effects were confirmed to be specific for individual cytokines by experiments using anti-human cytokine antibodies. It is likely that intestinal epithelial cells are local production sites of C3, C4, and factor B, and that local C syntheses in the intestine are independently regulated by several cytokines, derived from monocytes/macrophages and T cells resident in the mucosal microenvironment.
Induction by IL-9 and suppression by IL-3 and IL-4 of the levels of chromosome 14-derived transcripts that encode late-expressed mouse mast cell proteases.
Authors: Eklund K K , Ghildyal N , Austen K F , Stevens R L 
Published: December 2022

Abstract
Immature, rIL-3-dependent mouse bone marrow-derived mast cells (BMMC) contain high steady-state levels of the mouse mast cell protease (mMCP) 5 transcript but undetectable levels of the mMCP-1, mMCP-2, or mMCP-4 transcripts even though all four of their genes reside at a locus on chromosome 14. These mast cells can be induced by recombinant c-kit ligand (rKL) to obtain high steady-state levels of the mMCP-4 transcript and by rIL-10 to obtain high steady-state levels of the mMCP-1 and mMCP-2 transcripts. rIL-3 and rKL both elicit the differentiation of progenitor cells into immature BMMC and then stimulate their proliferation. We now report that although rIL-9 alone has no effect on BMMC proliferation as assessed by their incorporation of [3H]thymidine, rIL-9 in combination with rKL enhances the long term viability of BMMC. Furthermore, rIL-9 in the presence of rKL stimulates mouse BMMC to undergo a phenotypic change by inducing accumulation of high steady-state levels of the mMCP-1 and mMCP-2 transcripts. In contrast, in BMMC, the presence of rIL-4 suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts, the rIL-10-induced accumulation of the mMCP-1 and mMCP-2 transcripts, and the rKL-induced accumulation of the mMCP-4 transcript, but not the rIL-3-induced accumulation of the mMCP-5 transcript. The presence of rIL-3 also suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts. Because of their counter-regulatory actions on the steady-state levels of transcripts that encode three late-expressed serine proteases in BALB/cJ mice, rIL-4 and rIL-3 both inhibit the final stages of differentiation and maturation of mast cells. Because rIL-4, unlike rIL-3, is neither an inducer of early-expressed proteases nor alone a proliferative factor for BMMC, the counterregulatory actions of rIL-3 and rIL-4 on differentiation and maturation of these mouse mast cells are independent of their other functions.
Particle digestibility is required for induction of the phosphatidylserine recognition mechanism used by murine macrophages to phagocytose apoptotic cells.
Authors: Fadok V A , Laszlo D J , Noble P W , Weinstein L , Riches D W , Henson P M 
Published: December 2022

Abstract
One of the characteristic features of programmed cell death in vivo is the rapid recognition and removal of apoptotic cells by macrophages. Although there are several potential mechanisms by which the macrophage can identify a cell as apoptotic, it has been shown recently that murine-elicited macrophages stereospecifically recognize phosphatidylserine (PS) exposed on the surface of apoptotic cells. The particulate stimulus, beta-1, 3-glucan, stimulates bone marrow-derived macrophages to express several characteristics of inflammatory macrophages, and induced these cells to recognize PS on apoptotic cells; this activity was correlated with the ability to form rosettes with PS-expressing RBC. Induction of PS recognition in bone marrow-derived macrophages was associated with digestibility of the stimulus, because L, but not D amino acid particles or latex, were able to stimulate macrophage recognition of PS. The requirement for digestibility could be bypassed by the addition of exogenous TGF-beta, which induced macrophage recognition of PS after stimulation with either latex or D amino acid particles. That endogenously produced TGF-beta played a role in the glucan-stimulated response was indicated by the ability of anti-TGF-beta antibodies to inhibit digestible particle-induced recognition of PS. The induction of the PS recognition mechanism correlated well with the expression of other markers for the inflammatory phenotype. These studies indicate that the PS receptor may be a marker for the inflammatory phenotype, which appears to be induced by the phagocytosis of particulate digestible stimuli. Endogenously produced TGF-beta is suggested to play an autocrine or paracrine priming role in the induction of the PS receptor.