bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cobra venom factor: structural homology with the third component of human complement.
Authors: Vogel C W , Smith C A , Müller-Eberhard H J 
Published: January 2023

Abstract
The functional analogy between cobra venom factor (CVF), the complement-activating protein in cobra venom, and C3b, the activated form of the third complement component, prompted us to conduct a comparative analysis of structural properties of the two proteins derived from two phylogenetically distant species. We subjected CVF and human C3 and its physiologic cleavage products, C3b and C3c, to a variety of biochemical analyses. We report here structural similarities of these proteins, which include similarities in amino acid composition, far and near UV circular dichroism spectra, secondary structure, band patterns and pI values from isoelectric focusing, immunochemical cross-reactivity, ultrastructural morphology, and amino-terminal amino acid sequences. Analysis of these data reveals that, structurally, CVF resembles C3c more than C3b. We conclude that CVF is not the product of a convergent evolution, but is, in all likelihood, derived from a common C3 ancestor protein.
In vivo kinetics and nature of rat IgE-bearing lymphocytes after IgE stimulation.
Authors: Manouvriez P , Bazin H 
Published: January 2023

Abstract
Surface IgE-bearing (sIgE+) cells were studied in BN and rnu/rnu athymic rats after Nippostrongylus brasiliensis infection or i.p. injection of unpurified or purified IgE from plasmacytoma ascitic fluid. The number of sIgE+ cells increased markedly after a serum IgE increase without change in the proportion of sIgM+ and sIgD+ cells. A high percentage of the sIgE+ cells bore cytophilic IgE. Receptors for IgE were induced with a 2.56-micrograms IgE injection/100 g body weight and reached a maximum with 1.6 mg IgE/100 g body weight. They appeared less than 4 hr after a single injection of purified IgE. The number of IgE receptor-bearing cells reached a maximum plateau at 24 hr to day 3 after injection and declined thereafter, to reach the control level on day 9 or 11 after injection. Nearly all the sIgE+ cells of BN rats also bore sIgD, but the number of triple sIgE-sIgM-sIgD+ cells varied in a wide range. Maximum 4.5% of the sIgE+ cells of euthymic rats were T cells. More than 98% of the sIgE+ cells of nude rats were triple sIgM-sIgD-sIgE+ cells, and the majority were cytophilic IgE+. For the most part, the sIgM-sIgD-sIgE+ cells are probably not cells that can differentiate, as generally accepted, in IgE-producing cells. New interpretations of the role of these triple sIgM-sIgD-sIgE+ cells in IgE immune responses are necessary.
Down-regulation of human natural killer activity against tumors by the neutrophil myeloperoxidase system and hydrogen peroxide.
Authors: El-Hag A , Clark R A 
Published: January 2023

Abstract
There is growing evidence that natural killer (NK) cells play an important role in immune surveillance against tumors and certain infections. The coexistence of activated neutrophils with lymphocytes in tumor masses and inflammatory tissues suggests the possibility of interaction between secreted neutrophil products and nearby lymphocytes. We examined the susceptibility of lymphocyte NK activity to oxidative injury by the neutrophil myeloperoxidase (MPO) system and H2O2 with the use of a cellfree model system. Exposure of human mononuclear leukocytes (MNL) to MPO, an H2O2-generating system (glucose + glucose oxidase), and a halide (C1- or I-) resulted in marked suppression of MNL-NK activity, as measured by 51Cr release from K562 tumor targets (p less than 0.001). This suppression was dependent on the presence and activity of each system component and was blocked by azide and catalase, but not by heated catalase. In spite of the marked functional suppression of NK activity, MNL viability was more than 95% and target binding frequency was not affected. NK suppression was reversible after 24 hr in culture. The mechanism of suppression was dependent on the amount and rate of H2O2 delivered, and on MNL number. MPO was essential when H2O2 flux was low or when MNL numbers were high. As H2O2 flux increased or MNL numbers decreased, NK suppression gradually became MPO-independent and was mediated by H2O2 alone. The ability of the MPO system to compromise lymphocyte NK function may explain the in vitro inhibition of NK activity of mixed cell populations by the tumor promoter phorbol esters, because these agents are potent stimulants for neutrophil secretion of MPO and H2O2. This study may also provide a possible mechanism for the reported in situ NK activity suppression by adherent phagocytic cells during carcinogenesis in both humans and animals.
Regulation of human T lymphocyte surface antigen mobility by purinergic receptors.
Authors: Kammer G M , Rudolph S A 
Published: January 2023

Abstract
The present study was undertaken to establish whether the capping mechanism of normal human T lymphocytes is regulated by a purinergic receptor. Interaction of T lymphocytes with adenosine significantly increased the mobility of the T3, T4, and T8 surface antigens. This enhanced rate of capping was reflected by a significant decrement in the time intervals to achieve half-maximal capping. T lymphocytes preincubated with theophylline or isobutylmethylxanthine did not exhibit accelerated capping or a decrease in the time required for half-maximal capping in response to adenosine, suggesting that these agents inhibited the binding of adenosine to its receptor. A role for a cAMP-dependent pathway in capping was suggested by the observation that the phosphodiesterase inhibitor RO-201724 caused a decrease in the concentration of adenosine required to accelerate the capping process. Moreover, exposure of T lymphocytes to the cyclic nucleotide derivatives 8-N3-cAMP and 8-Br-cAMP mimicked the effect of adenosine, significantly reducing the time to half-maximal capping. Photoaffinity labeling of intracellular cAMP receptors with 32P-8-N3-cAMP indicated that adenosine caused occupancy of the receptors. This effect of adenosine was inhibited by theophylline, a known purinergic receptor blocker. The data support the concept that the T cell capping mechanism is mediated by an adenylate cyclase-coupled purinergic receptor that activates a cAMP-dependent pathway, and that this pathway is functional in the T3+, T4+, (inducer) and T3+, T8+ (suppressor) subsets.
B cell activation. VIII. Membrane immunoglobulins transduce signals via activation of phosphatidylinositol hydrolysis.
Authors: Coggeshall K M , Cambier J C 
Published: January 2023

Abstract
Considerable evidence indicates that cross-linking of B cell surface Ig results in a "first signal" in B cell activation. We have shown that transduction of this signal is manifest by changes in plasma membrane potential leading to increased expression of surface I-A antigen. In previous studies, we have provided evidence that suggests that this signal is transduced via phosphatidylinositol (PI) hydrolysis liberating diacylglycerol (DAG), which subsequently activates protein kinase C. These biochemical events are aspects of a transmembrane signal transduction mechanism that is common in nature and utilizes the PI metabolic cycle for generation of "second messenger" diacylglycerol. Here we report direct evidence that treatment of B cells with various antibodies to surface Ig results in activation of the PI cycle. Results suggest that the increased phospholipid metabolism that occurs in B cells in response to anti-Ig involves only those phospholipids in the PI cycle and is a consequence of turnover of existing lipid rather than de novo synthesis. Furthermore, we show that PI cycle activation requires cross-linking of membrane Ig and is inhibitable by increased intracellular cyclic AMP. These findings are particularly important in view of previous studies that have shown identical requirements for and inhibitability of induction of B cell membrane depolarization and increased I-A expression. Thus, these results are consistent with our previous hypothesis that early B cell activation events initiated by receptor Ig occupancy are mediated via PI hydrolysis, diacylglycerol generation, and protein kinase C activation.
In vitro studies on the cell-mediated immune response to human brain tumors. II. Leukocyte-induced coats of glycosaminoglycan increase the resistance of glioma cells to cellular immune attack.
Authors: Gately C L , Muul L M , Greenwood M A , Papazoglou S , Dick S J , Kornblith P L , Smith B H , Gately M K 
Published: January 2023

Abstract
We have examined the ability of cultured human glioma cells to elicit allogeneic cytolytic lymphocyte responses in vitro in order to delineate properties of glioma cells that may contribute to their ability to escape cellular immune attack. When glioma cells were cultured together with allogeneic peripheral blood mononuclear cells (PBMC) in mixed lymphocyte-tumor cultures (MLTC), it was observed that cells from eight of 12 glioma lines were surrounded by clear pericellular "halos," which appeared to impede contact between PBMC and the glioma cells. Enzymatic, histochemical, and immunochemical studies indicated that these halos represented glycosaminoglycan (GAG) coats that contained hyaluronic acid (HA) as a major constituent. Electron microscopic studies demonstrated the presence of many thin microvillous processes spanning the width of the halos. The presence of GAG coats around glioma cells in MLTC reduced the generation of cytolytic T lymphocytes specific for antigens on the glioma cells. Likewise, these cell coats decreased the lysis of glioma cells by cytolytic lymphocytes, once generated. The production of thick coats of GAG by glioma cells was induced by interaction of glioma cells with a nondialyzable factor produced by PBMC in culture. This factor did not cause glioma cells to release increased amounts of HA into the medium, but rather increased the production of HA that remained associated with the glioma cell surface. The formation of thick, protective GAG coats by glioma cells as a result of their interaction with the PBMC-derived factor constitutes a nonspecific suppressor mechanism that may contribute to the ability of this class of human solid tumors to evade cellular immune attack.
Treatment of disseminated leukemia with cyclophosphamide and immune cells: tumor immunity reflects long-term persistence of tumor-specific donor T cells.
Authors: Greenberg P D , Cheever M A 
Published: January 2023

Abstract
B6 mice bearing disseminated syngeneic FBL leukemia can be cured by treatment on day 5 with 180 mg/kg cyclophosphamide and 2 x 10(7) adoptively transferred syngeneic immune spleen cells. Complete tumor eradication in this model requires more than 30 days and is dependent upon the transfer of specifically immune T cells. To evaluate the relative contributions of host and donor T cells to tumor elimination and the maintenance of tumor immunity, donor cells obtained from Thy congenic mice were used for adoptive transfer. Thus, host and donor T cells could be readily distinguished by the expression of either Thy-1.2 or Thy-1.1 antigen. The results demonstrated that the majority of immunologically competent T cells present in hosts cured by adoptive therapy were of host origin. A small population of donor T cells, however, persisted long after transfer. At day 60, a time point shortly after tumor eradication had been completed, 5% of splenic T cells were of donor origin, and by day 120 this percentage had decreased to less than 2%. Functional studies performed at both time points revealed that this small number of residual donor T cells contained the subpopulation of tumor-reactive T cells present in the host. Thus, host T cells did not make a substantial contribution to the expression of the anti-tumor response and presumably have little role in either tumor eradication or the long-term maintenance of tumor immunity.
An in vitro system for the generation of suppressor cells and the requirement for B cells in their induction.
Authors: Hausman P B , Sherr D H , Dorf M E 
Published: January 2023

Abstract
An in vitro method for the generation of effector suppressor cells (Ts3) was developed. By utilizing this protocol, it was possible to investigate both the cellular and genetic requirements for suppressor cell induction. It was determined that populations containing Ts3 cells can be induced after a 4-day culture of spleen cells and antigen. These Ts3 cells are similar to Ts3 cells generated by in vivo immunization. Both populations are I-J+, bind NP hapten, bind NP hapten, bear receptors which share NPb idiotypic determinants with anti-NP antibodies, function during the effector phase of the immune response, and require activation with Ts2 cells. Generation of Ts3-containing populations required both nylon wool-nonadherent T cells and a nylon-adherent, B cell-enriched population from an Igh-identical donor. T cells cultured with antigen alone or with syngeneic macrophages and antigen did not develop suppressive activity. Lytic treatment of the nylon-adherent population with a B cell-specific monoclonal antibody (J11d) removed the ability to generate suppressor cells. These results imply that the induction of suppressor T cells requires B lymphocytes, and that this induction process is dependent on Igh-linked gene products.
Inhibition of mixed lymphocyte response by a rat monoclonal antibody to a novel murine lymphocyte activation antigen (MALA-2).
Authors: Takei F 
Published: January 2023

Abstract
A novel surface antigen expressed on activated and proliferating murine lymphocytes has been identified by a rat monoclonal antibody. The antigen, termed MALA-2, is also expressed on various lymphoid cell lines, but it is absent or present at very low densities on the majorities of unstimulated thymocytes and lymph node cells. Some cells in normal spleen and bone marrow seem to express the antigen at relatively high densities and they may represent proliferating cells in these tissues. MALA-2 has an apparent m.w. of 95,000 to 100,000 under both reducing and nonreducing conditions. The monoclonal antibody YN1/1.7 that reacts with this antigen partially inhibits Con A stimulation of spleen cells, but its inhibition of LPA stimulation is negligible. Furthermore, the antibody profoundly inhibits MLR. The inhibition of MLR by YN1/1.7 antibody is comparable to that caused by anti-transferrin receptor. The time course study suggests that the antibody may directly inhibit proliferating cell populations in MLR.
Interleukin 2 is both necessary and sufficient for the growth and differentiation of lectin-stimulated cytolytic T lymphocyte precursors.
Authors: Erard F , Corthesy P , Nabholz M , Lowenthal J W , Zaech P , Plaetinck G , MacDonald H R 
Published: January 2023

Abstract
Minimal requirements for the growth and differentiation of lectin-stimulated cytolytic T lymphocyte precursors (CTL-P) have been investigated. CTL-P from murine spleen were purified by staining with monoclonal anti-Lyt-2 antibodies, followed by positive selection on a fluorescence-activated cell sorter. Microcultures containing 2000 purified Lyt-2+ cells were set up with optimal concentrations of lectin (leukoagglutinin or concanavalin A) and pure interleukin 2 (IL 2) obtained either by immunoaffinity chromatography or recombinant DNA technology. Proliferation and generation of CTL activity in lectin-stimulated Lyt-2+ cells were IL 2 dose-dependent. Furthermore, no increased response was observed when crude supernatants containing other putative CTL differentiation factors were added, even when IL 2 concentrations were suboptimal. When highly purified Lyt-2+ cells contaminated by 1% Lyt-2- cells and less than 0.1% macrophages were cultured at limiting dilution, as few as 20 responding cells proliferated and differentiated into CTL in the presence of leukoagglutinin and pure IL 2; in fact, CTL activity and proliferation were strongly correlated in individual microcultures. In addition, 10 to 30% of individual CTL-P were growth-inducible under these experimental conditions. Together, these data show that the proliferation and differentiation of lectin-stimulated CTL-P can occur in pure IL 2 without any demonstrable requirement for other differentiation factors or accessory cells.
Antigen presentation by EBV-B cells to resting and activated T cells: role of interleukin 1.
Authors: Chu E T , Lareau M , Rosenwasser L J , Dinarello C A , Geha R S 
Published: January 2023

Abstract
We have previously demonstrated that Epstein Barr virus-transformed human B lymphocytes (EBV-B cells) present antigen to activated T cells (lines and clones) in a MHC-restricted manner. In the present study, using EBV-nonimmune donors, we demonstrate that EBV-B cells are unable to trigger tetanus toxoid (TT) antigen-specific proliferation in autologous highly purified resting T cells. EBV-B cells from these same individuals were able to present TT to autologous TT-specific activated T cell blasts (Tbl). The inability of EBV-B cells to present TT to resting T cells was not caused by defective antigen processing by EBV-B cells. Thus, paraformaldehyde treatment of antigen-pulsed EBV-B cells did not impair their ability to trigger proliferation of antigen-specific Tbl, and EBV-B cells pulsed with antigen in the presence of autologous TT-specific T cell blasts did not present antigen to resting T cells. Furthermore, antigen-specific proliferation of resting T cells triggered by monocytes was enhanced rather than suppressed by EBV-B cells. The addition of partially purified human IL 1 allowed EBV-B cells to present TT antigen to resting T cells, suggesting that failure to secrete IL 1 contributed to the failure of EBV-B cells to present antigen. IL 1 could not be detected in supernatants of EBV-B cells stimulated with Staphylococcus epidermidis, concanavalin A, and TT antigen in the presence or absence of up to 5% autologous T cells. The differential capacity of EBV-B cells to present antigen to resting T cells vs activated T cells correlated with the T cell requirement for IL 1, because a rabbit antibody to human IL 1 inhibited the monocyte-supported proliferation of resting T cells but not that of activated T cells. These results suggest that the inability of EBV-B cells to present antigen to resting T cells is related to their inability to secrete detectable IL 1.
Fc receptors on cultured myeloma and hybridoma cells.
Authors: Teillaud J L , Diamond B , Pollock R R , Fajtova V , Scharff M D 
Published: January 2023

Abstract
The specificity of the Fc gamma receptors on the X63.Ag8.653 nonproducing myeloma cell line has been examined for binding to IgG1-, IgG2a-, and IgG2b-containing antigen-antibody complexes. Complexes containing each of these subclasses bind, and the binding of each is inhibited by the others. Trypsin treatment did not inhibit the binding of any of these subclasses. Furthermore, the monoclonal anti-Fc receptor antibody 2.4G2 inhibits the binding of all three subclasses. These results, together with those of other investigators, suggest that there is a single FcR for IgG1, IgG2a, and IgG2b on mouse B cells which differs in its specificity from the macrophage Fc gamma R. This is confirmed by the fact that a mutant IgG2b myeloma protein which binds to the macrophage Fc gamma 1/gamma 2b receptor does not bind to the Fc gamma R on X63.Ag8.653.
Activation of the alternative pathway of complement by human peripheral nerve myelin.
Authors: Koski C L , Vanguri P , Shin M L 
Published: January 2023

Abstract
Destruction of peripheral nerve myelin (PNM) occurs as a consequence of a variety of pathologic conditions affecting the peripheral nervous system. In certain primary demyelinating neuropathies, several lines of evidence implicate complement in the pathogenesis of demyelination. In this study we demonstrate that human PNM consumes complement in vitro in the absence of specific antibody or C1 activation. Furthermore, activation of complement by PNM via the alternative pathway was shown by cleavage of C3 in normal human serum (NHS) and of B in C2-deficient serum (C2d-HS). Increasing consumption of hemolytic activity of C3 in Mg-EGTA-treated NHS was also noted with increasing amounts of PNM. Pronase treatment of PNM abolished C3 consumption, suggesting that a protein component exposed on the surface of myelin participated in the alternative pathway activation. When P0, the major amphiphilic glycoprotein of PNM, was incorporated into artificial lipid bilayers, the Po-liposomes consumed C3 activity in NHS containing Mg-EGTA. Pronase treatment of Po-liposomes abolished C3 consumption to the level of control liposomes, indicating that P0 was responsible for at least part of the activation seen with peripheral myelin.
Deactivation of guinea pig pulmonary alveolar macrophage responses to N-formyl-methionyl-leucyl-phenylalanine: chemotaxis, superoxide generation, and binding.
Authors: Daughaday C C , Mehta J , Spilberg I , Atkinson J P 
Published: January 2023

Abstract
Incubation of pulmonary alveolar macrophages (PAM) with the synthetic chemotactic tripeptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP) results in deactivation of PAM chemotaxis. The chemotactic response to 10(-8) M FMLP was inhibited 85% after 30 min of preincubation with 10(-6) M FMLP and 48% by 10(-8) M FMLP. Only the higher dose of FMLP (10(-6) M) caused deactivation of the chemotactic response to C5a (20%). Preincubation with partially purified C5a at a concentration of 100 microliter/ml produced a 32% inhibition of the PAM response to 10(-8) M FMLP. In contrast, preincubation with FMLP had no significant effect on superoxide generation, either at baseline or after stimulation. Levels of intracellular cyclic adenosine-3',5'-monophosphate (cAMP) increased in response to PGE1 in the presence of 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor, but FMLP failed to induce a change in cAMP levels. Studies of 3H-FMLP binding were consistent with two populations of membrane receptors with different affinities. Preincubation of PAM with FMLP did not result in a reduction of maximal binding. We conclude that FMLP induces deactivation of PAM chemotaxis, but cross-deactivation occurs only after high dose treatment. Unlike the PMN, macrophage chemotactic activation is not accompanied by an elevation in cAMP levels. These observations suggest that PAM chemotaxis is influenced by prior exposure to chemotactic stimuli, but other aspects of the PAM response diverge from that of PMN. The mechanism of deactivation of PAM does not appear to result from a shift in the dose-response curve or decreased availability of membrane receptors, but may involve uncoupling of post-receptor cellular responses.
Regulation of idiotope expression. I. The effect of antigen dose on expression of certain T15 idiotopes during primary IgM response to S. pneumoniae R36a.
Authors: Stout J T , Strickland F M , Cerny J 
Published: January 2023

Abstract
Clonal heterogeneity among B cells reactive to the same epitope may be determined through differences in idiotypy. It appears that clones bearing distinct idiotopes may constitute functionally distinct subpopulations. Data suggest that idiotopically distinct clones of PC-reactive B cells may be regulated independently of one another. We have looked to see whether individual T15+ clones may also differ in their requirements for activation. Here we examine the effect of immunizing doses of antigen on expression of two T15 idiotopes, B36-82 and B39-38, during both in vivo and in vitro primary responses to Streptococcus pneumoniae R36a (Pn) in CB-20 mouse strain. The idiotopes were detected on the specific antibody plaque-forming cells (PFC) by using monoclonal anti-idiotopic antibodies. We find that distinct patterns of idiotope expression are generated by stimulation with different doses of antigen. Immunization with suboptimal and super-optimal doses of Pn produced responses dominated by PFC expressing both idiotopes, whereas PFC induced by optimal antigen concentrations were primarily B36-82+ and B39-38-. These data indicate that the varying of antigen concentration may induce the response of different B cells bearing distinct idiotypes.