bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of iC3b with recombinant isotypic and chimeric forms of CR2.
Authors: Kalli K R , Ahearn J M , Fearon D T 
Published: December 2022

Abstract
CR2 is a component of a signal transduction complex on B lymphocytes that augments B cell responses to Ag. We have quantitatively assessed binding by the two isotypic forms of CR2 for two of its ligands, the polymerized iC3b (p(iC3b)) fragment of C3, and gp350/220, the EBV membrane protein. The recombinant 15-SCR or 16-SCR forms of CR2 bound p(iC3b) with identical affinities. Full binding activity of CR2 for p(iC3b) was observed with a chimera comprised of SCR-1 and -2 of CR2 fused to SCR-17 through -30 of CR1. Therefore, the alternatively spliced SCR-10a has no role in binding p(iC3b), and the binding activity of wild type receptor for iC3b can be reconstituted with SCR-1 and -2 of CR2. The binding affinities of the two isoforms of CR2 for soluble gp350/220 were also similar. Additional sites in the C3c region of C3 have been postulated also to interact with CR2. However, monomeric iC3b and C3d were equally effective in inhibiting the binding of p(iC3b) to CR2, indicating that the C3c region of iC3b does not contribute to the interaction of iC3b with CR2. Finally, the relative abilities of C3b and iC3b to bind to CR1 and CR2 were compared. The conversion of C3b to iC3b generated a ligand with an approximate 100-fold decrease in affinity for CR1 and a 10-fold increased affinity for CR2, resulting in a 1000-fold greater likelihood for binding to the latter receptor that may then promote B cell activation.
Complex regulation of macrophage colony-stimulating factor in the HL-60 promyelocytic cell line.
Authors: Sater R A , Cripe L D , Taylor J D , Niedel J E 
Published: December 2022

Abstract
The regulation of macrophage colony-stimulating factor (M-CSF) gene expression by phorbol esters and calcium ionophore (A23187) was studied in HL-60 cells. In untreated HL-60 cells, M-CSF transcripts were undetectable, but transcripts were present within 2 h of A23187 treatment or within 8 h of phorbol 12,13-dibutyrate (PdBu) treatment. Concurrent treatment of HL-60 cells with A23187 and cycloheximide (CHX) for 6 h led to a superinduction of message over A23187 treatment alone. But concurrent treatment with PdBu and CHX for 24 h abolished expression of the message normally present after 24 h of PdBu treatment. The role of new protein synthesis in transcriptional regulation of M-CSF was studied by run-on transcription assay. Untreated HL-60 cells or cells treated with CHX alone do not transcribe M-CSF mRNA. However, cells treated with A23187 for 6 h and CHX for 1, 3, or 6 h transcribed more M-CSF than cells treated with A23187 alone for 6 h. CHX also regulates M-CSF expression by message stabilization. The t1/2 of M-CSF mRNA was 45 min in cells treated with A23187 for 6 h or in cells treated with PdBu for 24 h, was over 2 h in HL-60 cells treated with A23187 for 6 h and CHX for 1 h, and was 3 h in cells treated with PdBu for 24 h and CHX for 1 h. We conclude that M-CSF gene expression can be differentially regulated in HL-60 cells and that new protein synthesis plays an important role in both the transcriptional and posttranscriptional regulation.
Lipophosphoglycan masks recognition of the Leishmania donovani promastigote surface by human kala-azar serum.
Authors: Karp C L , Turco S J , Sacks D L 
Published: December 2022

Abstract
Markedly elevated titers of anti-leishmanial antibodies are a hallmark of kala-azar. We investigated the role played by the lipophosphoglycan (LPG) in determining the reactivity of kala-azar serum with the surface of Leishmania donovani promastigotes. In assays performed with liver parasites there was negligible agglutination or fluorescent staining of LPG-bearing promastigotes by kala-azar serum, but strong reactivity in both assays with the use of an L. donovani mutant strain (R2D2) that lacks surface expression of LPG. Immunoprecipitation of lysates of 125I surface-labeled promastigotes indicated that kala-azar serum has reactivity with several surface proteins common to both the wild-type and R2D2 strains, and no reactivity with surface proteins unique to R2D2. Although direct ELISA showed that kala-azar serum recognizes purified promastigote LPG, inhibition ELISA suggested that such recognition is based solely upon reactivity with the normally unexposed core-anchor region of the molecule. We conclude that the poor reactivity of kala-azar serum with the surface of L. donovani promastigotes is caused by its lack of recognition of the exposed phosphodisaccharide repeat units of LPG, which in turn effectively mask the surface molecules that are recognized by kala-azar serum antibodies.
Molecular characterization of the mouse mannose-binding proteins. The mannose-binding protein A but not C is an acute phase reactant.
Authors: Sastry K , Zahedi K , Lelias J M , Whitehead A S , Ezekowitz R A 
Published: December 2022

Abstract
Mannose-binding proteins play a role in first line host defense against a variety of pathogens. We report the molecular cloning of two mouse mannose-binding proteins designated A and C based on their close identity with their rat homologues. The deduced amino acid sequence of the mouse mannose-binding proteins, as with rat and the human forms, have an NH2 terminus that is rich in cysteine that stabilizes a collagen alpha helix followed by a carboxyl- terminal carbohydrate binding domain. We further show that the mouse mannose-binding protein A mRNA, as with the human, is induced like the acute phase reactant serum amyloid P protein, yet the expression of mouse mannose-binding protein C mRNA is not regulated above its low baseline level. The expression of both mannose-binding proteins A and C mRNA is restricted to the liver under basal and stress conditions.
Modulation of cytolytic T lymphocyte functions by an inhibitor of serine/threonine phosphatase, okadaic acid. Enhancement of cytolytic T lymphocyte-mediated cytotoxicity.
Authors: Taffs R E , Redegeld F A , Sitkovsky M V 
Published: December 2022

Abstract
A specific and potent inhibitor of protein phosphatases 1 and 2A, okadaic acid (OA), and its inactive analog, tetramethyl ether (OA-TME), were tested in the cytotoxicity and granule exocytosis assays of CTL activation. At low concentrations OA enhanced, whereas at higher concentrations OA inhibited, CTL responses. The Ag-specific and retargeted cytotoxicity, granule exocytosis induced by target cell (TC), anti-TCR mAb, or PMA and A23187, and conjugate formation with TC were inhibited by pretreatment of CTL with OA as expected if protein phosphatases and protein dephosphorylation were indeed involved in the TCR-mediated signal transduction and effector responses of CTL. Cytotoxicity and granule exocytosis were unaffected by pretreatment of CTL with OA-TME. The inhibitory effect of OA on the exocytic response of CTL induced by TC and anti-TCR mAb can be dissociated from the inhibition of the response to PMA and A23187, suggesting the involvement of a serine and/or threonine protein phosphatase in the early events of transmembrane signaling. At lower concentrations, OA, but not OA-TME, was able to enhance the Ag-specific cytotoxicity and TC-induced exocytosis from CTL clones. The enhancement of these TCR-mediated responses of CTL was observed only if the activation was induced by the Ag on the TC surface, because OA did not enhance either the anti-TCR mAb-induced exocytosis of granules from the CTL clone or lysis of the Ag-nonbearing TC by CTL in a retargeting assay. The biphasic character of the effects of OA on CTL-TC interactions suggests the existence of at least two functionally distinct phosphatases in CTL. The ability of OA to enhance the Ag-specific response is unique and indicates the presence of an inhibitory phosphoprotein phosphatase that should be considered as a participant in the down-regulation of the cell-cell interactions between CTL and TC. The inhibitory effects of OA on both TC-induced and anti-TCR mAb-triggered CTL responses at higher concentrations point to the importance of yet another phosphatase in the CTL-TC interactions and in the TCR-mediated transmembrane signaling. The use of OA may help to decipher the details of biochemical changes involved in T lymphocyte effector functions.
Inhibition of antigen-driven proliferative responses and enhancement of antibody production during infection with Brugia pahangi.
Authors: Miller S , Schreuer D , Hammerberg B 
Published: December 2022

Abstract
Long standing Brugia pahangi infections in seven dogs, restricted to one rear limb popliteal lymph node and its afferent ducts, were monitored with regard to proliferative responses and antibody production specific for a PBS extract of B. pahangi (BpA) by cells from infected and uninfected lymph nodes and by PBL. Five of 10 dogs were negative for proliferative responses to BpA in node cells from infected limbs, yet they had positive PBL responses, and another was negative in both node cells and PBL. Production of BpA-specific antibody was detected in cultures of node cells from infected limbs of 9 of 10 dogs, but only in two cultures of node cells from uninfected limbs and not at all in PBL cultures. Three dogs with responsive node cells produced the least amount of anti-BpA antibody in culture. Injections of B. pahangi adult worm excretory/secretory products (ES), totaling 1 mg over 48 h, into the limb of the original infections in seven dogs, resulted in inhibition of Ag-driven proliferation by cell populations previously responsive to BpA. There was a loss of PBL responsiveness by all but one infected dog and a loss of node cell response by the two dogs previously responsive in infected and uninfected nodes. This loss of responsiveness lasted at least 28 days in three dogs. There was no evidence of suppression of responses to mitogens either before or after ES injection. In contrast, BpA-specific antibody production was greatly increased in node cells from infected limbs injected with ES. Similar injections into the uninfected limbs of two infected dogs produced no change of proliferative responses or of antibody production in the uninfected node. These results indicate that ES can modulate immune cell, Ag-driven proliferation, and simultaneously enhance antibody production in previously infected nodes. This may promote parasite survival by inhibiting cellular attack based on delayed-type hypersensitivity while directing immune responses toward production of antibodies that are less damaging to the adult helminth.
Treatment of murine B cell lymphoma with bispecific monoclonal antibodies (anti-idiotype x anti-CD3).
Authors: Demanet C , Brissinck J , Van Mechelen M , Leo O , Thielemans K 
Published: December 2022

Abstract
It has previously been reported that T lymphocytes can be targeted by using bispecific antibodies consisting of anti-target antibody and anti-CD3. In the present study, a bispecific mAb was developed by somatic hybridization of mouse hybridomas, one producing a mAb against the Id determinant of the mouse B cell lymphoma 38C13 and the other a mAb against a polymorphic determinant on murine CD3. The bispecific antibody, anti-38C13 x anti-CD3, is bi-isotypic (IgG1 x IgG2a) and was purified by ion exchange and affinity chromatography. The dual specificity of the hybrid hybridoma-produced mAb could be demonstrated by flow cytometry, the induction of T cell proliferation, the induction of IL-2 secretion by polyclonal T cells, and redirected lysis of the relevant target cells. The hybrid (bi-isotypic) Fc part of the bispecific antibodies was nonfunctional in FcR-dependent redirected lysis. In vivo studies demonstrate that this bispecific mAb could efficiently target T cells towards the tumor cells, resulting in long term survival and cure of the lymphoma.
Cytotoxic T lymphocytes induce different types of DNA damage in target cells of different origins.
Authors: Sellins K S , Cohen J J 
Published: December 2022

Abstract
Nuclear changes may be important in the mechanism of CTL-mediated lysis. Rapid cleavage of target cell DNA into oligonucleosomes has been demonstrated as a very early event in CTL-mediated killing of murine hematopoietic targets. However, the results presented herein and by other investigators have shown that this extensive dsDNA fragmentation does not occur in all CTL targets. In terms of actual DNA damage, there is a wide range in the extent and type of DNA cleavage in various targets. Differences exist at both the species and the cell lineage level. The extent of DNA damage generally corresponds to the efficiency of lysis; thus, murine hematopoietic cells, which undergo dsDNA fragmentation, are killed more rapidly and at lower E/T cell ratios than are murine nonhematopoietic cells, which sustain single-stranded nicks. Experiments using cloned CTL demonstrate that the same effector cell kills both hematopoietic and nonhematopoietic targets, producing different types of DNA damage. These observations indicate that the fate of the target cell DNA is determined by the nature of the target cell and not by the CTL. We propose that DNA damage results from an enzyme pathway inherent to the target, which is activated by, not transferred from, the CTL.
Eosinophil activation and T lymphocyte infiltration in allergen-induced late phase skin reactions and classical delayed-type hypersensitivity.
Authors: Gaga M , Frew A J , Varney V A , Kay A B 
Published: December 2022

Abstract
T lymphocyte infiltration is a well documented feature of classical delayed-type hypersensitivity (DTH) reactions. Recently, we have shown that T lymphocytes and activated (EG2+) eosinophils accumulate in the allergen-induced late phase skin reaction (LPR). To compare the kinetics and phenotypic composition of these T lymphocyte responses, LPR and DTH reactions of comparable induration size were induced in atopic subjects. In addition, DTH and LPR were compared between atopic and nonatopic subjects. In atopic individuals, allergen challenge elicited a perivascular influx of T lymphocytes that was predominantly CD4+. Eosinophil accumulation and activation were also prominent. There was no cellular response to allergen challenge in the nonatropic group. In both groups, DTH responses showed an intense T cell infiltrate which was more dense and dispersed than in the LPR. CD4+ T cells predominated but at 48 h CD8+ numbers were also significantly increased. In DTH, total leukocyte numbers (CD45+) were increasing at 48 h, whereas in the LPR, cell numbers reached a plateau between 24 and 48 h. T cell activation (shown by expression of IL-2R) was more prominent in DTH. Endothelial expression of HLA-DR was increased in both LPR and DTH, implying the local release of inflammatory cytokines in both reactions. Small but significant numbers of activated eosinophils (EG2+) were detected in atopics and non-atopics at 24 h in DTH but not at 48 h. These findings suggest that the allergen-induced LPR induced in atopic subjects is, at least in part, a form of cell-mediated hypersensitivity but with T cell kinetics that differ from classical DTH.
Beta 1 integrin (CD29) expression on human postnatal T cell subsets defined by selective CD45 isoform expression.
Authors: Pilarski L M , Yacyshyn B R , Jensen G S , Pruski E , Pabst H F 
Published: December 2022

Abstract
The integrin beta 1 (CD29) is a marker for total very late activation Ag integrins on cells, and exhibits considerable fluctuation in cell surface density at various stages of T cell development. We have analyzed beta 1 integrin expression on subsets of human thymus, and on T cells from healthy babies and children, in comparison to healthy adults aged 26 to 75. T cells from adult peripheral blood include a CD29-, a CD29lo, and a CD29hi set. Compared with adults, PBMC T cells from children have reduced numbers of both CD29lo and CD29hi subsets but equivalent numbers of CD29- T cells. The number of CD29hi T cells increases gradually with age, achieving adult levels only at about 26 yr of age; in aged adults (69 to 75 yr), nearly all T cells have a CD29hi phenotype. Most thymocytes and cord blood T cells, in contrast, have a single peak of CD29 staining that is intermediate to the two peaks seen in adults. Multi-negative progenitor and CD45RO- thymocytes (presumptive thymic generative line-age) are 98% CD29hi. Progenitor thymocytes and adult PBMC T cells express equivalent amounts of beta 1 and alpha 4, but progenitors are alpha 5hi, whereas PBMC T cells are alpha 5lo. T cells from children have reduced beta 1hi and alpha 5lo, but nearly comparable numbers of alpha 4hi. This suggests that the major very late activation Ag integrins during childhood may be alpha 5 beta 1 and alpha 4 complexed with an alternate beta chain. In children, the majority of CD29hi cells are also CD45RAhi, in contrast to the pattern in adults, in whom the majority of CD29hi T cells are CD45RA-. This suggests that in children, the main defense against infection may reside in the CD29hi45RAhi T cells, which have not yet made the transition to CD45RO and to bona fide memory status. The proliferative response to tetanus toxoid of 4- to 6-mo-old babies correlates with the number of CD29hi45RAhi T cells, suggesting that it derives at least in part from cells that do not express a "memory" phenotype. These observations show a pattern of alternating high and low density CD29 during T cell development, which is consistent with the idea that CD29 is a marker for functionally defined T cell sets. Analysis of the CD29 expression of CD29hi thymocytes developing in vitro supports this view. We suggest that the intensity of CD29 expression on a T cell varies, dependent upon the microenvironmental interactions required by a differentiating T cell.
Intravascular IL-8. Inhibitor of polymorphonuclear leukocyte accumulation at sites of acute inflammation.
Authors: Hechtman D H , Cybulsky M I , Fuchs H J , Baker J B , Gimbrone M A 
Published: December 2022

Abstract
IL-8 has been characterized primarily as a polymorphonuclear leukocyte (PMN) chemoattractant and proinflammatory mediator. Recently, we have reported that [Ala-IL-8]77 is secreted by activated cultured human endothelial cells and can function as a potent inhibitor of PMN adhesion to these monolayers. The pathophysiologic relevance of this in vitro observation was examined by determining the effects of intravascular or extravascular administration of IL-8 on PMN emigration at sites of acute inflammation in the skin of NZW rabbits. An i.v. bolus of [Ala-IL-8]77 (12 micrograms/kg) produced a marked and selective reduction of circulating PMN within 3 min, which returned toward preinjection levels within 30 min, and subsequently exceeded this level. A similar response was observed for circulating radiolabeled PMN, and gamma-scintigraphy determined that the lungs were the primary site of leukosequestration. During the 30- to 150-min interval after i.v. infusion of [Ala-IL-8]77, PMN emigration into acute inflammatory sites, elicited by various chemoattractants or cytokines, was significantly reduced, as judged histologically and quantitated with 51Cr-labeled PMN and myeloperoxidase measurements. Intravenous administration of [Ser-IL-8]72 yielded similar results. This inhibitory effect of i.v. IL-8 was transient and reinducible and did not reflect a suppression of the responsiveness of circulating PMN to chemoattractants. Intradermal injections of [Ala-IL-8]77 or [Ser-IL-8]72 induced dose-dependent PMN accumulation, which also was significantly reduced by i.v. administration of either form of IL-8. These results indicate that i.v. IL-8 can function as a PMN-directed leukocyte adhesion inhibitor and suggest that local secretion of IL-8 by activated endothelium may differentially modulate leukocyte-endothelial interactions at sites of acute inflammation.
Purified Fc epsilon R+ bone marrow and splenic non-B, non-T cells are highly enriched in the capacity to produce IL-4 in response to immobilized IgE, IgG2a, or ionomycin.
Authors: Seder R A , Plaut M , Barbieri S , Urban J , Finkelman F D , Paul W E 
Published: December 2022

Abstract
Non-B, non-T cells from spleen and bone marrow cells produce IL-4 in response to cross-linkage of high affinity receptors for Fc epsilon R or Fc gamma RII, and to treatment with calcium ionophores. Cells bearing high affinity Fc epsilon R constituted 1 to 2% of non-B, non-T cells of spleen and of total bone marrow cells from naive donors. In mice whose immune systems had been polyclonally activated by injection with anti-IgD antibodies or had been infected with Nippostrongylus brasiliensis larvae, the frequency of Fc epsilon R+ cells in splenic non-B, non-T cells was also 1 to 2% but in bone marrow from anti-IgD-injected mice donors the frequency was approximately 5%. Cell sorting experiments revealed that all of the capacity to produce IL-4 in response to immobilized IgE or IgG2a or to ionomycin was found in the Fc epsilon R+ fraction. Among the Fc epsilon R+ spleen cells from naive donors, the frequency of IL-4-producing cells was 1/20 to 1/40 whereas in mice that had been injected with anti-IgD or infected with N. brasiliensis, the frequency of IL-4 producing cells in the Fc epsilon R+ population was approximately 1/5.
Proteolysis of C3 on U937 cell plasma membranes. Purification of cathepsin G.
Authors: Maison C M , Villiers C L , Colomb M G 
Published: December 2022

Abstract
Covalent binding of C3 fragments to U937 cell membranes involved a cell surface-associated proteolytic activity. Two proteases able to cleave C3 were purified from U937 plasma membranes. Purification involved solubilization of the membranes and ion exchange chromatography. One of the purified proteases was identified as elastase, based upon a substrate specificity for benzyloxycarbonylalanine-o-nitrophenyl ester and complete inhibition by elastatinal and methoxysuccinyl-alanyl-alanyl-prolyl-valyl-chloromethyl-ketone. The other protease (m.w. 28,000) is cathepsin G, as deduced from the amino acid composition, the amino-terminal sequence, and the substrate specificity for succinyl-alanyl-alanyl-phenylalanine-p-nitroanilide. These two lysosomal proteases are present on the U937 cell surface, as confirmed by immunofluorescence analysis. Plasma membrane elastase and cathepsin G from U937 cells cleave C3 into C3a- and C3b-like fragments; further incubation leads to C3c- and C3dg-like fragments, as judged from SDS-PAGE analysis of the digests. Sequencing of the C3b-like fragment purified by reverse phase chromatography indicates that initial cleavage of C3 by purified cathepsin G occurs at two positions in the amino-terminal part of the alpha-chain, at a Arg-Ser bond located between residues 748 and 749 and at a Leu-Asp bond between residues 751 and 752. These proteases are, thus, able to generate, on the U937 surface, active fragments of C3, which are likely to be involved in cell-protein and cell-cell interactions.