bluuebunny/crossref_metadata_2025 huggingface dataset:
Stimulation of connective tissue-type mast cell proliferation by crosslinking of cell-bound IgE.
Authors: Takagi M , Nakahata T , Koike K , Kobayashi T , Tsuji K , Kojima S , Hirano T , Miyajima A , Arai K , Akabane T
Published: June 2004

Crosslinking of cell-bound IgE on mouse connective tissue-type mast cells (CTMC) by multivalent antigen or anti-IgE antibody induced clonal growth of CTMC in methylcellulose culture containing IL-3. Continuous presence of antigen, IgE antibody, and IL-3 in culture was required for extensive proliferation of CTMC. Optimal concentrations of antigen and anti-IgE antibody for proliferation of sensitized CTMC approximately corresponded to those for maximal histamine release from the cells, and it was observed that most dividing cells stimulated by antigen had pericellular degranulation halos in culture. Experiments of both single cell culture and serum free culture provided evidence for a direct effect of antigen stimulation on proliferation of CTMC. Neither accessory cells nor some factors in FCS were required for the clonal growth of CTMC in our culture condition. Compound 48/80, a direct stimulator of CTMC, also triggered histamine release from CTMC but failed to support their proliferation. These results suggest that stimulation of CTMC via IgE receptors not only triggers the release of chemical mediators from the cells but induces clonal growth of CTMC in the presence of IL-3. Our data indicate the possibility that antigen stimulation may play another role in the proliferation of CTMC.
A monoclonal antibody to sialophorin (CD43) induces homotypic adhesion and activation of human monocytes.
Authors: Nong Y H , Remold-O'Donnell E , LeBien T W , Remold H G
Published: June 2004

Treatment of human monocytes for 24-48 h with the anti-CD43 mAb L10 caused five- to sevenfold stimulation of hydrogen peroxide-producing capacity, an established characteristic of activated monocytes. Peroxide-producing capacity induced by L10 antibody (1.6 +/- 0.3 nmol H2O2/micrograms DNA/h) was comparable with that induced by IFN-gamma (1.3 +/- 0.4 nmol H2O2/micrograms DNA/h), but appeared more rapidly (maximal at 24 h) than in the IFN-gamma-treated monocytes (maximal at 48 h). Treatment of monocytes with L10 mAb also caused dramatic increase in aggregation (homotypic adhesion). Induction of monocyte aggregation by L10 mAb required incubation for 1-8 h in the presence of Mg2+ and was abrogated by TA-1, an anti-LFA-1-alpha mAb. Thus, L10-induced monocyte activation proceeds via a Mg2+-requiring aggregation stage involving LFA-1. Whereas the extent of monocyte aggregation induced by L10 mAb and by IFN-gamma were comparable, the L10-induced aggregation occurred more rapidly (maximal at 8 h) than the IFN-gamma-induced aggregation (maximal at 24 h). The more rapid appearance of aggregation and increased hydrogen peroxide capacity in L10-treated monocytes suggests that the L10-induced activation pathway is independent of IFN-gamma-and IFN-gamma-R dependent events. These findings suggest that the surface molecule CD43 is the receptor of an independent activation pathway that leads in lymphocytes to proliferation and in monocytes to activation.
Exacerbation of murine listeriosis by a monoclonal antibody specific for the type 3 complement receptor of myelomonocytic cells. Absence of monocytes at infective foci allows Listeria to multiply in nonphagocytic cells.
Authors: Rosen H , Gordon S , North R J
Published: June 2004

Treatment of mice with a rat mAb (5C6) specific for an epitope of the type 3 complement receptor of myelomonocytic cells severely interfered with the ability of the mice to resist infection with Listeria monocytogenes. Consequently, a sublethal infection was rapidly converted to a lethal one that resulted in death in 5 d. However, infection was only exacerbated if 5C6 was given earlier in infection, before mononuclear phagocytes populated sites of Listeria implantation in the liver and spleen. If given after day 3 of infection, 5C6 caused only a temporary increase in bacterial multiplication. The infection-enhancing effect of 5C6 was associated with failure of mice to focus mononuclear phagocytes at sites of bacterial multiplication of Listeria in liver hepatocytes and extracellulary in the spleen. This resulted in unrestricted multiplication of Listeria in hepatocytes and extracellularly in the spleen. The results are in keeping with the ability of 5C6 to inhibit the accumulation of myelomonocytic cells in peritoneal inflammatory exudates, as revealed by a previous study.
Identical peptides recognized by MHC class I- and II-restricted T cells.
Authors: Perkins D L , Lai M Z , Smith J A , Gefter M L
Published: June 2004

Previous data from many groups show that both class I and class II-restricted T cells recognize short synthetic peptides in the context of their respective MHC molecules (9-18), all of the peptides described to date are restricted to only a single class of MHC molecules; however, structural homology between the class I and II MHC molecules and the use of similar TCRs by class I and II-restricted T cells suggest that antigen recognition mechanisms are similar in both systems. To directly compare antigen recognition in the two systems, we analyzed peptides for the ability to function in both a class I and II-restricted system and found that seven of seven individual peptides tested stimulate both class I and II-restricted T cell responses. In addition, two of the peptides can function in different species stimulating both human class I and murine class II T cell responses. Thus, the process of T cell recognition of antigen in the context of MHC molecules was highly conserved in evolution not only between the class I and class II MHC systems, but also between the murine and human species.
Activation of natural killer cells via the p75 interleukin 2 receptor.
Authors: Phillips J H , Takeshita T , Sugamura K , Lanier L L
Published: June 2004

The IL-2R is composed of at least two subunits, the p55 (CD25/Tac) and p75 glycoproteins. The p75 IL-2R is expressed preferentially on resting human peripheral blood NK cells, but is not detected on substantial proportions of T and B lymphocytes, monocytes, or granulocytes. Anti-p75 IL-2R mAb substantially inhibits the early events associated with NK cell activation by IL-2, including inhibition of cytotoxic activity and induction of the CD69 early activation antigen. While anti-p55 IL-2R mAb alone failed to substantially inhibit the initial events of IL-2 stimulation, maximal inhibition of IL-2-induced cytotoxicity and proliferation was achieved by combining both anti-p55 IL-2R and anti-p75 IL-2R. Collectively, results from the present studies directly implicate the p75 IL-2R as the structure predominantly responsible for IL-2 activation of NK cells.
Triggering T cells by otherwise inert hybrid anti-CD3/antitumor antibodies requires encounter with the specific target cell.
Authors: Roosnek E , Lanzavecchia A
Published: June 2004

We used a purified bispecific antibody (Ab) against CD3 and an ovarian carcinoma (OVCA) antigen to ask whether the binding of a monovalent ligand to CD3 can induce triggering of T cells. In the presence of OVCA cells, this Ab bridges the CD3 complex to the target cell and triggers proliferation and cytotoxicity in T cells. In the absence of target cells, however, this monovalent Ab, even when bound to T cells at high levels, fails to induce any increase in cytosolic Ca2+, nor does it induce responsiveness to IL-2 or modulation of the CD3 complex. Because it is inert when bound monovalently, this hybrid Ab can be used to arm in vitro CTL clones, which then retain the capacity to kill the specific tumor for up to 2 d.
Induction of Fc epsilon R2/CD23 on human epidermal Langerhans cells by human recombinant interleukin 4 and gamma interferon.
Authors: Bieber T , Rieger A , Neuchrist C , Prinz J C , Rieber E P , Boltz-Nitulescu G , Scheiner O , Kraft D , Ring J , Stingl G
Published: June 2004

Human rIL-4 and human rIFN-gamma are able to induce the expression of the low affinity receptor for IgE (Fc epsilon R2/CD23) on normal human epidermal Langerhans cells, whereas IL-2 and PMA have no effect. A synergistic effect is observed when both cytokines are combined. These receptors are synthesized de novo by the LC since cycloheximide completely inhibits the appearance of Fc epsilon R2/CD23. Fc epsilon R2/CD23+ LC may have a major role in the pathogenesis of atopic eczema, as well as in the regulation of IgE synthesis.
Genetic analysis of the human tumor necrosis factor alpha/cachectin promoter region in a macrophage cell line.
Authors: Economou J S , Rhoades K , Essner R , McBride W H , Gasson J C , Morton D L
Published: June 2004

The 615-bp 5' flanking region of the human TNF-alpha/cachectin gene was isolated and ligated to the luciferase reporter gene. In addition, a series of truncated promoter constructs was generated by exonuclease III digestion. The promoter activity of these constructs was studied in a transient transfection system using the TNF-alpha-producing U937 cell line. Full-length and truncated TNF promoter constructions extending from -615 to -95 bp relative to the transcription start site (TSS) could be induced by phorbol esters. A construct truncated to within 36 bp of the TSS (and within 11 bp of the TATAA box) was inactive. Therefore, the phorbol ester responsive is localized in the TNF/cachectin promoter to a relatively short region proximal to the TATAA box.
Interleukin 7 production and function in stromal cell-dependent B cell development.
Authors: Sudo T , Ito M , Ogawa Y , Iizuka M , Kodama H , Kunisada T , Hayashi S , Ogawa M , Sakai K , Nishikawa S
Published: June 2004

The role of IL-7 in the stromal cell-dependent B cell development was investigated using two stromal cell clones, ST2 and PA6; the former supports B lymphopoiesis while the latter can not. We demonstrate here that: (a) the ability of the stromal cell clone to produce IL-7 correlates well with the stromal cell activity to support B lymphopoiesis; (b) IL-7 production by ST2 is inducible rather than constitutive; (c) the IL-7-dependent B cell itself is a potent inducer of IL-7 production by ST2; (d) addition of rIL-7 to the PA6 layer renders this in vitro environment B lymphopoietic; and (e) the differentiation from early B progenitor to pre-B cell requires both IL-7 and other stromal cell molecule(s) yet to be identified.
Demonstration of delta rec-pseudo J alpha rearrangement with deletion of the delta locus in a human stem-cell leukemia.
Authors: Begley C G , Aplan P D , Davey M P , de Villartay J P , Cohen D I , Waldmann T A , Kirsch I R
Published: June 2004

It has been hypothesized that a rearrangement between the delta recombining element (delta Rec) and a pseudo J alpha gene serves to delete the TCR-delta locus before rearrangement of the TCR-alpha genes. We have now sequenced a direct, site-specific rearrangement between the delta Rec element and a pseudo J alpha gene in a human leukemic stem-cell line. Putative "N-sequence" addition was noted at the site of recombination, suggesting that this event occurred at a time when the enzyme(s) involved in N-region addition were active in this cell. This provides support for the view that deletion of the TCR-delta locus is required before rearrangement of the TCR-alpha chain genes.
Interleukin 5 and phenotypically altered eosinophils in the blood of patients with the idiopathic hypereosinophilic syndrome.
Authors: Owen W F , Rothenberg M E , Petersen J , Weller P F , Silberstein D , Sheffer A L , Stevens R L , Soberman R J , Austen K F
Published: June 2004

We report that the hypodense eosinophil population in three patients with corticosteroid-unresponsive IHES was uniquely long lived ex vivo in the absence of exogenous cytokines. Serum or plasma from these patients conferred prolonged viability ex vivo to normodense eosinophils from reference donors and converted them to a functionally activated hypodense phenotype. In that antibody against IL-5 neutralized this activity in IHES serum, excessive quantities of this cytokine may account for the characteristic eosinophilia and long-lived, functionally augmented eosinophil phenotype in this disorder.
Heterogeneous lobular distribution of hepatocytes expressing acute-phase genes during the acute inflammatory reaction.
Authors: Bernuau D , Legrès L , Lamri Y , Giuily N , Fey G , Feldmann G
Published: June 2004

Functional heterogeneity in the lobule with regard to plasma protein synthesis is still debated. Therefore, we have localized in liver sections from normal rats and from rats with turpentine-induced AIR the mRNA and protein products of three genes with different alterations in their hepatic expression during an AIR: alpha 2M and alpha 1PI, two positively reacting acute-phase genes, and alpha 1I3, a negative acute-phase reactant. In normal liver, all hepatocytes expressed alpha 2M and alpha 1I3 mRNA, but a preferential expression of alpha 2M and alpha 1I3 mRNA and protein in the PP and ML zones was observed. During an AIR, the level of alpha 2M mRNA increased fourfold in the cytoplasm of PP and ML hepatocytes, while the level of cytoplasmic alpha 1I3 mRNA was decreased about fourfold in the same zones, with parallel variations in the expression of the corresponding proteins. In contrast, no significant modulation of the RNA and protein concentrations of both genes was detected in PV areas. alpha 1PI mRNA was expressed at the same levels in the three lobular zones in normal liver, but staining for the alpha 1PI protein was more intense in the PV zones. During the acute-phase response alpha 1PI mRNA levels were increased twofold in all three lobular zones, and alpha 1PI staining became homogeneous within the lobule. These results demonstrate that the location of a hepatocyte with the liver lobule can influence the expression of the three genes under study both at pre- and post-translational levels, in basal conditions, as well as during modulation of their expression during the inflammatory reaction.
Self recognition by T cells. I. Bystander killing of target cells bearing syngeneic MHC antigens.
Authors: Duke R C
Published: June 2004

Activated CTL can kill any cell to which they bind or by which they are bound. This observation has been used to determine whether alloreactive CTL can recognize cells bearing self-MHC. When activated by their specific targets, 19 CTL clones of 4 different specificities and origins killed bystander targets bearing syngeneic but not third-party MHC antigens. Using target cells derived from MHC-recombinant animals, syngeneic bystander killing was shown to be restricted to a single self MHC-encoded molecule. These results provide the first clear demonstration that T cells, or more precisely CTL, are capable of self recognition in the absence of their specific antigen. Our findings support the model that T cell repertoire selection occurs as a result of positive selection during maturation in the thymus of precursor cells whose antigen receptors have low but real affinity for self-MHC.
Murine natural killer cells express functional Fc gamma receptor II encoded by the Fc gamma R alpha gene.
Authors: Perussia B , Tutt M M , Qiu W Q , Kuziel W A , Tucker P W , Trinchieri G , Bennett M , Ravetch J V , Kumar V
Published: June 2004

We report evidence that murine NK cells express a functional Fc gamma RII encoded by the Fc gamma RII alpha gene. Several lines of indirect evidence indicate that freshly obtained NK cells from mice of several strains bear a functional Fc gamma RII: (a) anti-Fc gamma RII antibody 2.4G2 detects a small but significant proportion of sIg- cells and a small proportion of the 2.4G2+ cells are included in the Thy-1+ population; (b) sIg- lymphocytes contain 2.4G2+ and Fc gamma R-bearing cells in similar proportions; (c) binding of particulate immune complexes by sIg- lymphocytes is completely inhibited by 2.4G2; (d) 2.4G2+ cells mediate greater than 50% of the spontaneous cytotoxicity in sIg- splenic lymphocytes. Direct evidence for the presence of Fc gamma RII on murine NK cells is provided by the results of two-color immunofluorescence studies performed on splenic lymphocytes from C57BL/6 mice showing coexpression of NK-1.1 and 2.4G2. Studies of in vitro propagated homogeneous NK cell populations confirm that murine NK cells express only Fc gamma RII and that this Fc gamma R is functional, as shown in experiments of inhibition of ADCC by the anti-Fc gamma RII antibody 2.4G2. The results of studies at the molecular level show that an Fc gamma RII alpha transcript identical to that expressed in macrophages is the only molecule encoding Fc gamma RII in murine NK cells.
Tolerance in transgenic mice expressing class II major histocompatibility complex on pancreatic acinar cells.
Authors: Lo D , Burkly L C , Flavell R A , Palmiter R D , Brinster R L
Published: June 2004

To study the nature of tolerance to antigens not expressed by cells of the lymphoid system, expression of class II MHC I-E was targeted to the acinar cells of the exocrine pancreas in transgenic mice (elastase [EL]-I-E). Despite the absence of detectable I-E in the thymus of EL-I-E transgenic mice, both thymocytes and peripheral T lymphocytes were tolerant to I-E, and the pancreas was free of autoimmune infiltrates. Nontolerant T cells adoptively transferred into irradiated or T-depleted transgenic mice rapidly destroy the I-E+ components of the pancreas; however, adoptive transfer of nontolerant T lymphocytes into nonirradiated transgenic mice do not. These results suggest that tolerance in transgenic mice is maintained by some peripheral tolerance mechanism. However, further studies indicate that tolerance in transgenic mice is not maintained by specific Ts cells. For example, cell mixing experiments both in vitro and in vivo fail to reveal dominant unresponsiveness. Furthermore, nontolerant T cells injected into otherwise unmanipulated EL-I-E mice can be primed in situ (by injections of I-E+ spleen cells) to destroy the I-E+ acinar cells.
T cell determinants of myelin basic protein include a unique encephalitogenic I-E-restricted epitope for Lewis rats.
Authors: Offner H , Hashim G A , Celnik B , Galang A , Li X B , Burns F R , Shen N , Heber-Katz E , Vandenbark A A
Published: June 2004

The major encephalitogenic epitope for Lewis rats is the 72-89 sequence of guinea pig basic protein (GP-BP) or rat basic protein (Rt-BP). T cells responsive to this epitope are I-A restricted and preferentially express the V alpha 2:V beta 8 gene combination in their TCR. In this work, we describe for the first time the delayed appearance of T cells specific for additional discrete determinant of BP, the nonencephalitogenic 55-68 sequence of GP-BP restricted by I-A, and the encephalitogenic 87-99 sequence of Rt-BP restricted by I-E. The TCR V alpha 2:V beta 8 gene combination was expressed by both encephalitogenic GP-BP S72-89 and Rt-BP S87-99 T cell specificities but not by GP-BP 44-68-specific T cells. This is the first demonstration of I-E-restricted encephalitogenic T cells in Lewis rats and supports the conclusion that the I-E class II locus is involved in autoimmune diseases.
Streptococcal cell wall arthritis. Passive transfer of disease with a T cell line and crossreactivity of streptococcal cell wall antigens with Mycobacterium tuberculosis.
Authors: DeJoy S Q , Ferguson K M , Sapp T M , Zabriskie J B , Oronsky A L , Kerwar S S
Published: June 2004

Primary lymph node cells derived from streptococcal cell wall arthritic rats or those derived from adjuvant arthritic rats proliferated in response to cell wall antigens derived from either streptococcal cell walls or those from M. tuberculosis. In addition, two T cell lines have been isolated from lymph nodes of rats during the chronic phase of streptococcal cell wall arthritis. These T cell lines transfered clinical disease to naive syngeneic irradiated recipients, and they proliferated in the presence of cell wall antigens derived from streptococci or antigens derived from Mycobacterium but failed to proliferate in the presence of the 65-kD antigen (containing the sequence TFGLQLELT) derived from Mycobacterium. These observations indicate that T cells play a crucial role in the pathogenesis of streptococcal cell wall arthritis and suggest that antigenic crossreactivity exists between cell walls of group A streptococci and antigens derived from Mycobacterium. The 65-kD Mycobacterium protein is not involved in the observed antigenic crossreactivity.
Diversity of the class II (I-Ak/I-Ek)-restricted T cell repertoire for influenza hemagglutinin and antigenic drift. Six nonoverlapping epitopes on the HA1 subunit are defined by synthetic peptides.
Authors: Burt D S , Mills K H , Skehel J J , Thomas D B
Published: June 2004

H-2k-restricted T cell clones derived from CBA mice infected with X31 (H3N2) influenza virus, were shown to recognize distinct, nonoverlapping sequences within the HA1 subunit of the viral hemagglutinin (HA) using synthetic peptides. Three I-Ak-restricted T cell sequences were identified within HA1 68-83, 120-139, and 269-288, and two recognition sites presented in the context of the I-Ek molecule were mapped to HA1 sequences 226-245 and 246-265. T cell clones specific for these regions of HA1 demonstrated varying abilities to differentiate between natural variant viruses that had accumulated substitutions within their HA molecules as a result of antigenic drift. Clones that recognized sequences HA1 226-245 and HA1 246-265 failed to discriminate between natural variants and focused on conserved sequences within these epitopes. A majority of T cell clones were sensitive to amino acid substitutions that have featured in antigenic drift occurring within three major antigenic sites of the HA1 subunit; substitutions at HA1 residues 78 (V)/83(K) and 275(D)/278(I) within the HA1 subunit of mutant viruses correlated with a 75% reduction in the proliferative response for T cell clones specific for sequences HA1 68-83 and HA1 269-288, respectively. Furthermore, a clone that recognized HA1 120-139 was nonresponsive to a mutant virus HK/71, implicating amino acids at HA1 position 129(G) and/or 132(Q) within this sequence as crucial for recognition. Our data, together with the previous finding that sequence HA1 53-63 is also a major I-Ak-restricted T cell recognition site, demonstrate a level of diversity in the T cell recognition of influenza HA, within a single mouse haplotype hitherto unrecognized, and imply that the T cell repertoire diversity against foreign antigens may be greater than previously assumed. Furthermore, the frequency at which HA-specific T cells have been identified that focus on amino acids within the HA1 subunit of HA also featuring in antigenic drift, suggests that a failure of MHC class II-restricted T cells to recognize specific epitopes within mutant HA molecules may contribute significantly to the capacity of variant influenza viruses to evade immune recognition.
A human endothelial cell-restricted, externally disposed plasmalemmal protein enriched in intercellular junctions.
Authors: Muller W A , Ratti C M , McDonnell S L , Cohn Z A
Published: June 2004

We have raised an mAb to a previously undescribed 135-kD externally disposed integral membrane protein that is enriched in the intercellular junctional domain of cultured human umbilical vein endothelial cells. This protein localizes at the appositional surfaces of cells as they become confluent and is stably expressed in the junctional zones of confluent monolayers. This protein is expressed in situ on continuous endothelia of all blood vessels in all human tissues examined. Moreover, this protein, as determined by mAb immunocytochemistry, is not expressed by any other cell type. This protein may mediate endothelial-specific functions restricted to the intercellular domain. It may also serve as a unique cell surface marker for the identification and purification of human endothelial cells.
Multiple molecular forms of human lactoferrin. Identification of a class of lactoferrins that possess ribonuclease activity and lack iron-binding capacity.
Authors: Furmanski P , Li Z P , Fortuna M B , Swamy C V , Das M R
Published: June 2004

Lactoferrin (Lf), the major iron-binding component of milk, also a major constituent of the specific granules of neutrophils involved in antimicrobial activity and a glycoprotein thought to play a role in regulatory functions in the hematopoietic system as well as other physiologic activities, is shown to occur in three isoforms. One, Lf-alpha, binds iron; the other two, Lf-beta and Lf-gamma, express potent RNase activity, but do not bind iron. The three isoforms are very similar or identical in Mr, pI, partial proteolytic peptide patterns, NH2-terminal amino acid sequence, and reactivity with mAbs and polyclonal antisera against the RNase and Lf, respectively. The finding of structurally similar but enzymatically distinct forms of Lf may be related to the diverse functions of the molecule.
Leukocyte function-associated antigen 1 is an activation molecule for human T cells.
Authors: Wacholtz M C , Patel S S , Lipsky P E
Published: June 2004

The leukocyte function-associated antigen 1 (LFA-1) molecule is well established as a surface protein involved in cellular adhesion and interaction, but there has been little information about whether engagement of this molecule can also directly modify cellular activation. These studies demonstrate that crosslinking the LFA-1 molecule on human T cell clones transmits a unique signal to the cell. Crosslinking LFA-1 alone did not increase intracellular calcium ([ CA2+]i), nor did crosslinking LFA-1 activate the cells as measured by IL-2 production or [3H]thymidine incorporation. However, when CD3 and LFA-1 were crosslinked, a more prolonged calcium signal was observed than when CD3 alone was crosslinked. Moreover, IL-2 production and DNA synthesis were greatly augmented. These responses could be demonstrated when LFA-1 was crosslinked via either the alpha or the beta chain, and required surface expression of the LFA-1 molecule as no enhancement was observed in T cell clones from a child with leukocyte adhesion deficiency. The enhancement of cellular activation by LFA-1 did not require that it be directly crosslinked to the CD3 complex. Thus, crosslinking LFA-1 alone with isotype-specific secondary antibodies on cells also pretreated with an anti-CD3 mAb of a different Ig isotype stimulated the cells as effectively as crosslinking both surface antigens with GaMIg. Similarly, a delayed, but sustained increase in [Ca2+]i was elicited. This increase in [Ca2+]i and the enhanced functional responses required engagement of CD3 with an intact bivalent anti-CD3 mAb, as crosslinking LFA-1 on cells also reacted with Fab fragments of an anti-CD3 mAb did not increase [Ca2+]i, nor activate the cells. These data indicate that LFA-1 can convey activation signals to T cells. Synergism in signaling can be observed upon crosslinking of LFA-1 and independently crosslinking CD3. In the physiologic interaction between T cells and accessory cells, the interaction of LFA-1 with its ligand, intercellular adhesion molecule 1, may therefore not only facilitate cellular adhesion, but also may amplify T cell activation by delivering costimulatory signals.
Interleukin 3-dependent mediator release in basophils triggered by C5a.
Authors: Kurimoto Y , de Weck A L , Dahinden C A
Published: June 2004

The anaphylatoxin C5a is a potent trigger for basophil degranulations, but in contrast to IgE-dependent basophil activation, it does not result in the synthesis of sulfidoleukotrienes (leukotriene C4/D4/E4). Thus, degranulation and the generation of lipid mediators are separately regulated cellular responses. Exposure of human blood basophils to the cytokine IL-3 alone does not induce the release of histamine in cells from most donors and never leads to the generation of LTC4, indicating that IL-3 is not a direct agonist for basophil mediator release. However, preincubation of basophils with IL-3 enhances the degranulation response to C5a. Most importantly, IL-3 "primes" basophils to release large amounts of leukotriene C4 after challenge with C5a (mean of 50 gp LTC4 per nanograms cellular histamine), while neither peptide alone is capable of inducing the formation of bioactive lipids. This effect is dose dependent, occurring at IL-3 concentrations considerably lower than are required to stimulate the growth of bone marrow progenitor cells. IL-3 affects the extent but not the time course of basophil degranulation, and leukotriene release of cells sequentially exposed to IL-3 and C5a occurs very rapidly concomitant with degranulation. A preincubation of the basophils with IL-3 is strictly required for C5a-induced LTC4 synthesis, but not for an enhancement of degranulation. Priming for C5a-induced lipid mediator generation occurs rapidly after exposure of the cells to IL-3, starting at 1 min and reaching maximal effects at 5 min, but this altered state of responsiveness is relatively long lasting. Cell fractionation studies indicate that the basophil is the source of lipid mediators and that IL-3 affects the basophil response directly. This study demonstrates that IL-3 is a potent modifier of effector functions of mature basophils; this is possibly of greater in vivo significance than its growth factor properties. The large amounts of LTC4 formed after triggering of IL-3-primed basophils may not only enhance but also qualitatively change the pathophysiological consequences of complement activation, and this might be important in the pathogenesis of immediate type hypersensitivity reactions, shock syndromes, and inflammation.
Alveolar macrophage elimination in vivo is associated with an increase in pulmonary immune response in mice.
Authors: Thepen T , Van Rooijen N , Kraal G
Published: June 2004

A single intracheal dose of liposome-encapsuled dichloro-methylene-diphosphonate resulted in the elimination of alveolar macrophages (AM) from the lung, creating a model to study the in vivo role of AM in the pulmonary immune response. Using intratracheally administered trinitrophenyl-keyhole limpet hemocyanin (TNP-KLH), the kinetics of the response, the location and number of TNP-specific antibody-forming cells, and the different Ig classes of the antibodies produced were studied in AM-depleted animals. The results show that AM elimination has a dramatic effect on the pulmonary immune responses against TNP-KLH. An increase in APC in lung-associated lymph nodes and a prolongation of the response is found, as well as an introduction of APC in lung tissue. In both experimental groups, the majority of the TNP-specific antibodies produced was IgG, followed by IgA and IgE, while very few IgM antibodies could be detected. We conclude from these results that AM are likely to play a role in controlling the pulmonary immune response in a suppressive way, thereby limiting the possible damage caused by severe immune responses in lung tissue.
Antibody-dependent antitumor cytotoxicity by human monocytes cultured with recombinant macrophage colony-stimulating factor. Induction of efficient antibody-mediated antitumor cytotoxicity not detected by isotope release assays.
Authors: Munn D H , Cheung N K
Published: June 2004

Macrophage colony-stimulating factor (M-CSF) is known to stimulate proliferation of monocyte/macrophage progenitors and enhance in vitro antitumor cytotoxicity by murine macrophages. In this paper we have shown that recombinant human M-CSF causes human peripheral blood monocytes to differentiate in culture into metabolically active macrophage-like cells. These cells mediate very efficient antibody-dependent cellular cytotoxicity (ADCC) against human melanoma and neuroblastoma cell lines in the presence of two murine IgG3 mAbs (3F8 and R24). They also mediate antibody-independent cytotoxicity (or cytostasis) to a lesser extent. Human serum had an inconsistent effect on ADCC, but often induced similar high levels of ADCC. Cytotoxicity was measured using a novel ELISA to detect surviving tumor cells after ADCC. Two conventional isotope-release assays (51Cr and [3H]TdR) underestimated or entirely failed to detect ADCC by M-CSF-activated monocytes. Optimal activation occurred with 100-300 U/ml of M-CSF, and required 9-11 d for completion. Most of the M-CSF cultured monocytes expressed the low-affinity Fc receptor (CD16). ADCC by cells of the monocyte/macrophage lineage using murine IgG3 mAbs may have significance for the immunotherapy of human malignancies.
An antigen-independent contact mechanism as an early step in T cell-proliferative responses to dendritic cells.
Authors: Inaba K , Romani N , Steinman R M
Published: June 2004

Dendritic cells bearing antigen efficiently aggregate and stimulate antigen-specific T cells. We describe an experimental model in which an initial, apparently antigen-independent binding step is followed by ligation of the TCR. The model is the polyclonal response to mAb to the CD3 portion of the TCR complex. Epidermal and thymic dendritic cells utilize low levels of Fc receptors to present the anti-CD3 mAb and induce mitogenesis. Within 3 h of coculture, most of the dendritic cells have formed clusters with the resting T lymphocytes, and these clusters are the site for subsequent DNA synthesis and cell growth. However, the binding of dendritic cells to T cells proceeds as efficiently in the absence of anti-CD3 as in its presence, and anti-FcR mAb does not block. CD3 and Fc receptors are essential for the subsequent mitogenesis response in dendritic-T cell clusters. Because an exogenous ligand for the TCR does not seem to be required for the extensive polyclonal clustering of resting lymphocytes to dendritic cells, we suggest that an antigen-independent mechanism mediates the initial interaction. This clustering seems essential for T cell growth since we do not detect, in two-chamber experiments, soluble lymphocyte-activating factors that originate from dendritic-T cell aggregates and that activate anti-CD3-coated T cells.
Analysis of the first two waves of thymus homing stem cells and their T cell progeny in chick-quail chimeras.
Authors: Coltey M , Bucy R P , Chen C H , Cihak J , Lösch U , Char D , Le Douarin N M , Cooper M D
Published: June 2004

Chick-quail chimeras were used to study precursor/progeny relationships of hemopoietic stem cells (SC) that enter the embryonic thymus in waves to give rise sequentially to the TCR-1+, TCR-2+, and TCR-3+ lineages of T cells. The first wave of SC and their progeny were examined by grafting thymus from 9-d chick embryos (E9) into E3 quails. mAbs specific for chick T cell antigens were used to trace the development of T cells in the recipients. All three lineages of TCR-bearing cells were generated from the first wave of SC. The cortico-medullary transit time was several day shorter for the TCR-1 subpopulation than for the TCR-2 subpopulation, and the peripheral seeding of TCR-2 cells also occurred later in development. The duration of thymocyte production from the first wave of SC that entered the thymus was approximately 3 wk, during which gradual cortical to medullary replacement by second wave SC progeny occurred. When the latter was examined, after transplantation of E7 quail thymus into E3 chick embryos, a sequential generation pattern for the TCR-1 and TCR-2 cell progeny was not evident. Finally, recirculation of T cells to the thymus medulla was defined in this avian model.
Vaccinia virus hemagglutinin. A novel member of the immunoglobulin superfamily.
Authors: Jin D Y , Li Z L , Jin Q , Hao Y W , Hou Y D
Published: June 2004

Striking similarities between vaccinia virus hemagglutinin (VVHA) and proteins belonging to the Ig superfamily clearly indicate that VVHA, a 315-amino acid glycoprotein expressed on the surface of the infected cells, is a novel viral protein that can be added to the expanding list of the Ig superfamily. Its deduced amino acid sequence contains one Ig-like domain at the NH2 terminus, followed by two tandem repeating units and a hydrophobic region, suggestive of membrane spanning. The results offer an opportunity for the further study of the probable evolutionary and possible functional relationship between VVHA and other members of the Ig superfamily. Our observation, together with a recent finding that human CMV possibly encodes a protein similar to the MHC class I antigens (13), provides evidence supporting the fact that the viral capture of cellular Ig-related genes is more common than expected in vaccinia and other viruses, and that usage of an Ig-like domain as recognition signals might be extended from higher animals to animal viruses.
Inhibition of human macrophage colony formation by interleukin 4.
Authors: Jansen J H , Wientjens G J , Fibbe W E , Willemze R , Kluin-Nelemans H C
Published: June 2004

We investigated the effects of human rIL-4 on in vitro hematopoiesis. A profound inhibition of macrophage colony formation by IL-4 was observed, whereas colony growth of other lineages was not affected. Inhibition of macrophage colony growth was not restricted to GM-CSF-induced colony growth but was also present in cultures stimulated with M-CSF. This inhibition was not only observed in cultures of light density bone marrow cells, but also in cultures of monocyte- and T lymphocyte-depleted bone marrow cells. Since a similar inhibition was observed in cultures of CD34+HLA-DR+-enriched bone marrow cells, a direct action of IL-4 on monocyte-committed progenitor cells is suggested.
Prostaglandins from human T suppressor/cytotoxic cells modulate natural killer antibacterial activity.
Authors: Garcia-Peñarrubia P , Bankhurst A D , Koster F T
Published: June 2004

We have recently described potent antibacterial activity of purified human NK cells. Here we show that this function is regulated by T cytotoxic/suppressor CD8+ cells. Thus, coculture of NK and CD8+ cells for 3 h or longer times abrogated the expression of the NK antibacterial activity, and of two activation markers IL-2R and transferrin receptor (Tf-R). The suppressive activity was mediated by PGE2 as demonstrated by direct PGE2 determination in CD8+ cell free supernatants, and by inhibition of CD8+ cell suppression with indomethacin or piroxicam in vitro. We also found that resting T cytotoxic/suppressor cells purified by negative selection produce higher amounts of PGE2 than adherent cells like monocytes and macrophages, and that these concentration levels are in the range of concentrations known to suppress a significant number of in vitro immunologic functions.
Tumor necrosis factor identified in multiple sclerosis brain.
Authors: Hofman F M , Hinton D R , Johnson K , Merrill J E
Published: June 2004

Frozen brain specimens from patients with multiple sclerosis (MS) and other neurologic diseases were analyzed using immunocytochemical techniques for the presence of TNF. In brain lesions in MS, and subacute sclerosing panencephalitis, TNF+ cells were demonstrated. At the lesion site in MS, TNF+ staining is associated with both astrocytes and macrophages. These observations were not made in Alzheimer's disease or normal brain tissue. The presence of TNF in MS lesions suggests a significant role for cytokines and the immune response in disease progression.
In vivo expression and function of hybrid Ia dimers (E alpha A beta) in recombinant and transgenic mice.
Authors: Anderson G D , David C S
Published: June 2004

We have found cell surface expression of an E alpha molecule in recombinant and transgenic mouse strains lacking an E beta molecule. Flow cytometry has shown low level expression of E alpha in B10.RQB3 (I-AqEk alpha) and B10.RFB2 (I-AfEk alpha) mice. We have also found that B10.Q (H-2q) mice can express the Ek alpha transgene. Since these strains do not have functional E beta chains, we propose that the E alpha A beta hybrid dimers are formed in low numbers and can be picked up by FACS analysis. So far we have not been able to identify these hybrid molecules by cytotoxicity or immunoprecipitation. The E alpha/A beta molecule can function in vivo during thymic selection in the clonal deletion of two V beta TCR subsets, V beta 11 and V beta 6, which have been shown to interact with the intact I-E molecule.
Isolation and characterization of (gamma, delta) CD4+ T cell clones derived from human fetal liver cells.
Authors: Aparicio P , Alonso J M , Toribio M L , Marcos M A , Pezzi L , Martínez-A C
Published: June 2004

Lymphocytes isolated from human fetal liver and expanded in vitro in IL-2-containing media reveal the existence of CD4+ gamma, delta T cells. These cells display differential features of double-negative and CD8+ gamma, delta T cells as well as of CD4+ alpha, beta T cells. Thus, they failed to lyse targets in lectin-mediated killing assays and to perform classical helper functions. These results add new information necessary for a better understanding of the physiological role of the gamma, delta T cells.
Passive immunization against tumor necrosis factor partially abrogates interleukin 2 toxicity.
Authors: Fraker D L , Langstein H N , Norton J A
Published: June 2004

Passive immunization against TNF allowed non-tumor-bearing C3H/HEN mice and tumor-bearing C57BL/6 mice to tolerate significantly more doses of IL-2 before death (p less than 0.005 and p less than 0.001, respectively). The antitumor effect of IL-2 against both 3-d and 10-d pulmonary metastases was maintained in mice treated concurrently with neutralizing antibodies to TNF. In one experiment with 10-d pulmonary metastases, increased administration of IL-2 made possible by passive immunization against TNF significantly improved the antitumor response compared to equitoxic doses of IL-2 and control antibody. The results indicate that TNF is a mediator of IL-2 toxicity but contributes minimally to the antitumor effects of IL-2. Strategies to inhibit TNF may improve the therapeutic index of IL-2 as a neoplastic agent.
Human gamma interferon strongly upregulates its own gene expression in peripheral blood lymphocytes.
Authors: Hardy K J , Sawada T
Published: June 2004

The product of the human IFN-gamma gene was found to be a powerful upregulatory stimulus for its own gene expression in lectin-activated human PBMC. The INF-gamma autosuperinduction response was further enhanced by "priming" PBMC with IFN-gamma. Primed cells maximally upregulated their levels of IFN-gamma specific mRNA 4-fold faster and more than 20-fold higher than mock-stimulated cells. High mRNA levels persisted for several days after stimulation, and enhanced secretion of biologically active IFN-gamma paralleled the observed upregulation of gene expression. Producer cells demonstrating this response were found to be primarily localized to the rosette E- (leu 11+) fraction of PBMC and appear to be of the LGL/NK variety. Whether the autosuperinduction phenomenon occurs through direct or indirect effects of IFN-gamma on producer cells is still unclear. These results may be important both to an understanding of the pathogenesis of immune dysfunction and to the design of more effective immunotherapy.
Correlation of structure with T cell responses of the three members of the HLA-DRw52 allelic series.
Authors: Gorski J , Irle C , Mickelson E M , Sheehy M J , Termijtelen A , Ucla C , Mach B
Published: June 2004

A third allele at the DRB3 locus, DRw52c, represents an intermediate sequence between DRw52a and DRw52b and may have arisen by a gene conversion-like event. The recognition of cells bearing these molecules by a number of alloreactive and antigen-specific DR-restricted T cell clones was analyzed. On the basis of a theoretical model of HLA class II structure, distinct amino acid clusters have been identified as motifs controlling TCR recognition. These are located both in the cleft and in the alpha-helical edge of the MHC class II recognition platform. Motifs shared between two alleles may restrict public T cell clones.
Class I MHC can present an endogenous peptide to cytotoxic T lymphocytes.
Authors: Whitton J L , Oldstone M B
Published: June 2004

Since class I MHC glycoproteins may function by "screening and selecting" degraded proteins, we wished to determine whether very short peptides made within a cell were detected and bound by MHC, and presented for T cell perusal. We show that a 22 amino acid viral sequence containing a Db-restricted nonameric CTL epitope is sufficient to direct CTL recognition/lysis of H2b target cells. The mechanism of epitope presentation is by the "natural" endogenous route, and appears to direct lysis as effectively as wild-type virus infection, in which the epitope is part of a 236 residue glycoprotein.
Transforming growth factor beta specifically enhances IgA production by lipopolysaccharide-stimulated murine B lymphocytes.
Authors: Coffman R L , Lebman D A , Shrader B
Published: June 2004

The addition of TGF-beta to cultures of LPS-stimulated murine B cells causes a approximately 10-fold enhancement of IgA production, yet causes a 10-fold decrease in total Ig production. IL-2 and, to a lesser extent, IL-5 synergize with TGF-beta to further enhance IgA production and partially reverse the inhibition of total Ig production. IgA constitutes only approximately 0.1% of total Ig in LPS-stimulated cultures, but that percentage rises to 15-25% in cultures to which TGF-beta and IL-2 are added. TGF-beta induces a substantial increase in IgA production from sIgA- B cells but inhibits IgA production by sIgA+ cells. This finding suggests that TGF-beta acts as an isotype-specific switch factor for IgA.
In vivo administration of histoincompatible lymphocytes leads to rapid functional deletion of cytotoxic T lymphocyte precursors.
Authors: Martin D R , Miller R G
Published: June 2004

It is well established that a single intravenous injection of F1 lymphocytes can rapidly and specifically reduce the ability of a parental recipient to generate CTL against donor alloantigens in a subsequent MLR. By fluorescently labeling the injected cells, we have been able to identify, and if desired, remove them in cell suspensions prepared from recipient spleen and lymph node. The injected cells, whether F1 or syngeneic, appeared to form part of the normal recirculating pool. Removal of injected F1 cells from responder lymph node or spleen cell suspensions had no effect on the response reduction observed in the 5-d in vitro MLR (typically 80% reduction for responder cells taken 2 d after injection of F1 cells). When the frequency of CTL precursors (CTLp) was measured by limiting dilution, it was reduced to the same degree as the MLR response, implying that response reduction is due to a reduction in the number of activatable CTL in the responder cell suspension. An equal mixture of responder cells from treated (i.e., F1 injected) and control mice gave a measured CTLp frequency equivalent to the average of the separate frequencies, implying the absence of suppressor cells active in vitro. Labeled F1 cells recovered from a first recipient could be used to induce response reduction in a second recipient. The results are discussed in terms of APCs that functionally delete rather than stimulate CTLp that recognize them (i.e., a "veto mechanism"). These experiments appear to rule out a role for in vivo-induced suppressor cells up to 8 d after injection of semiallogeneic cells but do not address the question of whether they are induced at later times.
Glucocorticoid-mediated inhibition of endotoxin-induced intratumor tumor necrosis factor production and tumor hemorrhagic necrosis and regression.
Authors: North R J , Havell E A
Published: June 2004

Intravenous injection of 25 micrograms of bacterial endotoxin on day 9 of growth of the SA1 sarcoma results in extensive necrosis of the core of this tumor and in its subsequent complete regression. Tumor hemorrhagic necrosis and regression failed to occur in mice that were given a subcutaneous injection of cortisone acetate or dexamethasone 12 h before being giving endotoxin. Inhibition of tumor hemorrhagic necrosis and regression by glucocorticoids was associated with inhibition of endotoxin-induced intratumor TNF production that normally takes place several h after endotoxin is given. In contrast, glucocorticoids had no effect on the ability of intravenously injected rTNF to cause tumor hemorrhagic necrosis and regression. The results lend further support to the belief that TNF is the predominant mediator of endotoxin-induced hemorrhagic necrosis of established murine tumors, and that hemorrhagic necrosis is a prerequisite for the immunologically mediated regression that follows.