bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopic and hydrodynamic studies of protein A-immunoglobulin G soluble complexes.
Authors: Hanson D C , Phillips M L , Schumaker V N 
Published: December 2022

Abstract
The soluble complexes formed by reacting staphylococcal protein A (SpA) with rabbit immunoglobulin G (IgG) antibodies were characterized by hydrodynamic and electron microscopic methods. In moderate SpA excess, equilibrium mixtures of SpA and rabbit IgG formed four discrete complexes that sedimented at approximately 7, 10, 13, and 15S. The putative complexes were visible by electron microscopy and appeared to contain one, two, three, and approximately five molecules of IgG. Probably because of its elongated shape, SpA was not clearly visible in these mixtures or in control preparations of SpA alone. Both native IgG and IgG modified by cleavage of its single-hinge disulfide bond formed similar complexes on interaction with SpA. It was possible to resolve heterogeneous mixtures of IgG-SpA complexes by using an analytical ultracentrifuge equipped with a photoelectric scanner interfaced to a small computer. The relative concentrations and sedimentation velocities of different complexes in a mixture were determined from computer-generated integral and derivative plots. Both hydrodynamic and electron microscopic methods revealed that the distribution of complexes was sensitive to the IgG to SpA molar ratio. The relative amounts of faster complexes increased as the IgG to SpA molar ratio was increased. Surprisingly, when the IgG to SpA molar ratio was greater than or equal to 2, the complexes were converted into a unique 17S complex. This rather unprecedented transformation was reversible: the addition of excess SpA caused the dissociation of the 17S complex into a mixture of the 7, 10, 13, and 15S structures. The average translational diffusion coefficient of the 17S complex was 2.62 +/- 0.13 Ficks. In the electron microscope, the complex appeared to be exceptionally compact with an average diameter of 287 A. The stoichiometry of the 17S complex, together with sedimentation equilibrium, diffusion, and electron microscopic measurements, indicated that it is composed of four molecules of IgG and two molecules of SpA.
A model for the formation and interconversion of protein A-immunoglobulin G soluble complexes.
Authors: Hanson D C , Schumaker V N 
Published: December 2022

Abstract
We present a model for the formation and interconversion of the soluble complexes formed by reacting staphylococcal protein A (SpA) with rabbit immunoglobulin G (IgG) antibodies. The basic elements of the model are developed from reported hydrodynamic and electron microscopic studies of these complexes (see accompanying companion paper), together with established structural and binding properties of IgG and SpA. The model includes specific symmetry and binding requirements for IgG-SpA combination, and a steric constraint between neighboring IgG molecules. We discuss how such a constraint could influence the assembly and distribution of equilibrium complexes. After formulating a convenient symbolism for representing IgG-SpA complexes, the suggested model is used to construct plausible structures for the four predominant complexes observed in moderate SpA excess. Distributions of these stable complexes at different IgG:SpA ratios, together with LeChatelier's principle and a straightforward thermodynamic derivation, are used to predict likely arrangements of equilibrium structures. Also, a scale model of the unique IgG4-SpA2 complex formed in IgG excess is constructed from reported x-ray diffraction and amino acid sequence data. An intuitive thermodynamic argument is used to show that the suggested steric constraint could cause the rather unprecedented reversible transformation of the four 7 to 15S complexes into the unique 17S complex. A computer simulation is used to predict equilibrium concentrations of the various proposed complexes at different IgG:SpA ratios. In support of the suggested structures, the calculated thermodynamic distributions agree surprisingly well with those measured with the ultracentrifuge. We point out how the proposed arrangements of the complexes, and in particular the 17S complex, can account for many of their novel properties, such as antigen-induced conformational changes. Reported differences in complement activation and precipitate formation by SpA complexes formed with antibodies from various species are also discussed with regard to possible differences in structural arrangements of the complexes.
The fate of E. coli lipopolysaccharide after the uptake of E. coli by murine macrophages in vitro.
Authors: Duncan R L , Morrison D C 
Published: December 2022

Abstract
The fate of bacterial lipopolysaccharide (LPS) after the uptake of Escherichia coli by macrophages in vitro was studied. The LPS of the galactose epimerase-deficient E. coli J5 mutant was specifically radiolabeled with [3H]galactose by growing the organism in a basic salts medium containing galactose. Control bacteria were uniformly radiolabeled by growth in [14C]glucose and unlabeled galactose-containing medium. Surface constituents of E. coli were also labeled with 125I. After in vitro phagocytosis of labeled E. coli by murine peritoneal exudate macrophages, the rate of exocytosis of LPS, as assessed by release of 3H over a 72-hr period, was considerably reduced in comparison with other bacterial constituents (14C and 125I release). The [3H]galactose-labeled material exocytosed from macrophages and that remaining intracellularly (obtained from macrophage lysates) were isolated by cesium chloride (CsCl) density gradients and were shown to have altered density profiles as compared with purified E. coli LPS. The macrophage-"processed" [3H] galactose-containing fractions from CsCl density gradients of culture supernatants or macrophage lysates were capable of clotting Limulus amebocyte lysate. The [3H]galactose material obtained from 48-hr macrophage lysates and culture supernatants could also induce a lethal response in actinomycin D-treated mice. These data suggest that bacterial LPS may be selectively retained by the macrophage and that the post-phagocytic events that result in bacterial degradation are not accompanied by the degradation of LPS. Furthermore, although the LPS may be modified by the macrophage, it retains its biologic activity.
Regulation of human natural killing. III. Mechanism for interferon induction of loss of susceptibility to suppression by cyclic AMP elevating agents.
Authors: Leung K H , Koren H S 
Published: December 2022

Abstract
In this study we demonstrated that human NK cells activated by IFN or poly I:C were partially resistant to suppression by PGE2, PGD2, PGA2, PGI2, dibutyryl cAMP, isoproterenol, and theophylline. This partial loss of inhibition was not due to endogenous PG production because the addition of indomethacin to cultures stimulated with IFN or poly I:C did not prevent the partial loss of sensitivity to PGE2. NK cells incubated in the presence of PGE2 overnight, however, were not sensitive to inhibition. IFN or poly I:C did not stimulate PG synthesis nor elevate intracellular cAMP levels of NK cells. On the other hand, IFN or poly I:C diminished the accumulation of intracellular cAMP levels in NK cells in response to PGE2 stimulation. Dibutyryl cAMP and theophylline suppressed the cytolytic activity of the unstimulated cells more than that of the activated cells. A possible mechanism for the IFN-induced unresponsiveness to PGE2 may be a compartmentalized loss of cAMP responsiveness. Cycloheximide, puromycin, emetine, and actinomycin D blocked NK activation by IFN and poly I:C as well as the acquisition of resistance to PGE2-mediated suppression.
The role of mitogens and lymphokines in the induction of ornithine decarboxylase (ODC) in T lymphocytes.
Authors: Fidelus R K , Laughter A H , Twomey J J 
Published: December 2022

Abstract
Polyamine synthesis occurs early in lymphocyte activation after stimulation with antigen or mitogen. Ornithine decarboxylase (ODC) is the primary enzyme in the polyamine cascade. We have examined the induction of ODC by mitogens and/or lymphokines in human peripheral blood T lymphocytes. When isolated populations of monocytes and T lymphocytes were stimulated with phytohemagglutinin (PHA) there was little or no change in ODC activity. The combination of T lymphocytes and monocytes enhanced mitogen-induced ODC activity 10-fold. Several interleukin 1 (IL 1)-containing supernatants and fractionated human IL 1 were capable of substituting for monocytes in supporting PHA induction of ODC in T lymphocytes. Interleukin 2 (IL 2) and IL 2-containing supernatants were also capable of increasing ODC activity in T lymphocytes in the absence of monocytes. Lymphokines alone in the absence of PHA could not induce ODC. We conclude that both mitogens and monocytes are required for the induction of polyamine synthesis in T lymphocytes, and that supernatants containing IL 1 or IL 1 and IL 2 can substitute for monocytes in the induction of ODC in mitogen-stimulated T lymphocytes.
Macrophage activation to kill Leishmania tropica: defective intracellular killing of amastigotes by macrophages elicited with sterile inflammatory agents.
Authors: Hoover D L , Nacy C A 
Published: December 2022

Abstract
Resident peritoneal macrophages and macrophages elicited by injection of C3H/HeN mice with sterile inflammatory agents were exposed to amastigotes of Leishmania tropica in vitro and treated with lymphokines. Resident macrophages developed the capacity to kill intracellular parasites; microbicidal activity of activated resident cells ranged between 60 and 80%. In contrast, inflammatory macrophages responded poorly to lymphokines for intracellular killing of amastigotes; microbicidal activity of cells elicited with chronic inflammatory agents ranged between 0 and 45%. Defective intracellular killing of L. tropica by inflammatory macrophages was independent of the agent used to elicit the cells, but was clearly associated with the number of immature macrophages in the population. That intracellular killing capacity may reflect the presence of a killing mechanism in tissue-derived cells that is not yet developed in undifferentiated macrophages is supported by studies with peripheral blood monocytes: these cells were also incapable of eliminating intracellular amastigotes in the presence of potent activating factors. These observations on inflammatory macrophage interactions with amastigotes may provide important insights into the chronic nature of leishmanial disease.
Macrophage activation to kill Leishmania tropica: kinetics of macrophage response to lymphokines that induce antimicrobial activities against amastigotes.
Authors: Oster C N , Nacy C A 
Published: December 2022

Abstract
Lymphokine (LK) treatment of resident peritoneal macrophages from C3H/HeN mice induced two antimicrobial activities against Leishmania tropica: increased resistance of activated macrophages to infection with amastigotes and intracellular destruction of those parasites that entered activated cells. The onset and duration of these two antimicrobial activities were quite different. Resistance to infection was observed as early as 4 hr after the addition of LK, became maximal at 8 hr, and persisted in a subpopulation of treated cells for as long as 72 hr. In contrast, intracellular killing occurred with as little as 4 hr of LK treatment after infection, and maximal killing was observed in cultures exposed to LK 24 hr. Intracellular killing capacity of lymphokine-treated cells was progressively lost in macrophages treated longer than 12 hr before exposure to parasites. This decay in ability to destroy intracellular L. tropica was also seen in macrophages cultured longer than 12 hr before LK treatment, and may reflect loss of macrophage responsiveness to LK with increasing time in vitro. Thus, treatment of macrophages with lymphokines induced both a stable change in cell-parasite interactions, resistance to infection, and a short-lived capacity to destroy intracellular amastigotes.
Heterogeneity of infection enhancement of dengue 2 strains by monoclonal antibodies.
Authors: Halstead S B , Venkateshan C N , Gentry M K , Larsen L K 
Published: December 2022

Abstract
Seven dengue (DEN) 2 virus strains were studied for antibody-dependent enhancement (ADE) of infection in P388D1 mouse macrophage-like cells by using a panel of five DEN 2 monoclonal antibodies. DEN 2 strains were of diverse temporal, geographic, and disease origins. By hemagglutination inhibition and a plaque-reduction neutralization test in LLC-MK2 cells, two of the monoclonal antibodies were type specific and three were flavivirus group reactive. In LLC-MK2 cells, the seven DEN 2 viruses each were neutralized by all five monoclonal antibodies. In P388D1 cells, two DEN 2 strains were enhanced by only three monoclonal antibodies, two by four antibodies, and three by all five antibodies, demonstrating that in some instances enhancement is epitope related and not a concentration-dependent function of virus-antibody interactions. However, ADE did not segregate with determinants exhibiting either the flavivirus group or the dengue type specificity. The presence or absence of enhancement determinants on DEN 2 strains did not correlate with the geographic origin of virus or the severity of disease yielding the strain. The heterogeneous distribution of enhancement determinants may provide a valence mechanism contributing to a multiple increase of infection enhancement in macrophages.
Elucidation of the topography and determination of the protective epitopes on the E glycoprotein of Saint Louis encephalitis virus by passive transfer with monoclonal antibodies.
Authors: Mathews J H , Roehrig J T 
Published: December 2022

Abstract
We have identified and characterized eight antigenic epitopes on the 53,000 dalton envelope (E) glycoprotein of Saint Louis encephalitis (SLE) virus by using monoclonal antibodies. One of these epitopes (E-1c) encoded for the type-specific biologic functions of hemagglutination (HA) and neutralization (N). Injection of 50 ng of anti-E-1c antibody protected the majority of mice from peripheral challenge with 100 i.p. LD50 of SLE virus. Similar levels of protection with antibodies specific for other epitopes usually required greater than or equal to 1000-fold additional antibody. Attempts to block N or protection at the E-1c antigenic domain by using antibody to several other SLE epitopes that strongly competed for the E-1c site were unsuccessful. Enhancement of protection was observed with mixtures of the more cross-reactive antibodies. The E-1c antibody was also effective in abrogating SLE virus replication until neural invasion occurred. On the basis of these findings, the topologic arrangement and function of the eight SLE E glycoprotein epitopes on the virion spike is proposed.
Immunologic memory to phosphocholine. IV. Hybridomas representative of Group I (T15-like) and Group II (non-T15-like) antibodies utilize distinct VH genes.
Authors: Chang S P , Perlmutter R M , Brown M , Heusser C H , Hood L , Rittenberg M B 
Published: December 2022

Abstract
The anti-phosphocholine (PC) memory response elicited in BALB/c mice by phosphocholine-keyhole limpet hemocyanin (PC-KLH) contains two groups of antibodies distinguished by their fine specificity for PC and p-nitrophenylphosphocholine (NPPC). Group I antibodies are inhibited by both PC and NPPC, while Group II antibodies are inhibited appreciably only by NPPC; only Group I antibodies are dominated by the T15 idiotype. Anti-PC hybridomas representative of the memory response to PC-KLH were produced to examine the variable region genes expressed by memory B cells. Two IgM hybridomas were of the Group I type, because they were inhibited by both PC and NPPC and they bound to the pneumococcus R36A. However, only one of these antibodies (PCM-2) expressed a T15 idiotope, while the other (PCM-1) did not express any of three T15 idiotopes. Despite its negative T15 idiotype profile, N-terminal amino acid sequencing of PCM-1 purified heavy chain and Southern blots of the hybridoma DNA indicated that it utilizes the T15 VH and JH1 genes. Three hybridomas, IgG1, IgM, and IgE, typical of Group II antibodies, were examined; these were negative for three T15 idiotopes and displayed measurable avidity only for NPPC in a PC-protein binding inhibition assay. These three hybridoma antibodies, like serum Group II IgG1, did not measurably bind to the bacterium R36A. The heavy chain amino termini of all three of these antibodies were inaccessible for Edman degradation. Southern blots of DNA from the IgG1 hybridoma revealed the T15 VH gene to be in the germ line configuration only and unassociated with any JH segment, indicating that this Group II antibody utilizes a VH gene different from the T15 family. These results signify that, whereas some diversity of the (anti-PC) memory response may be generated by somatic diversification of variable regions important in the primary response, a significant contribution to the overall heterogeneity of memory antibodies originates in the expression of additional variable region genes.
Regulation of IgM and IgD synthesis in B lymphocytes. II. Translational and post-translational events.
Authors: Yuan D 
Published: December 2022

Abstract
Studies investigating the relative rates of biosynthesis of mu- and delta-polypeptide chains in normal resting B lymphocytes have shown that the translation rate of mu m is about sevenfold higher than that of delta m, thus reflecting the relative abundance of mRNA encoding these two chains. The turnover rate of cell surface IgM is faster, however, than that of cell surface IgD, resulting in higher expression of cell surface IgD relative to IgM under steady state conditions. LPS stimulation of B lymphocytes induces the complete cessation of synthesis of the delta-chain, thus accounting for the gradual disappearance of IgD from the cell surface of activated cells.
Production of large quantities of human immunoglobulin in the ascites of athymic mice: implications for the development of anti-human idiotype monoclonal antibodies.
Authors: Abrams P G , Ochs J J , Giardina S L , Morgan A C , Wilburn S B , Wilt A R , Oldham R K , Foon K A 
Published: December 2022

Abstract
Human-murine hybridomas, generated by fusion of human CLL cells with non-Ig-secreting murine myeloma NS-1, and secreting the IgM kappa expressed on the CLL cell surface, were grown in the peritoneal cavity of doubly pristane-primed nude mice to produce large quantities of highly concentrated human IgM kappa for the development of anti-idiotype monoclonal antibodies. Although the hybridomas secreted only 0.8 to 1.5 micrograms/ml/10(6) cells in tissue culture, they produced 8 to 12 ml of ascites from two mice containing 1.7 mg/ml of human IgM. Partial purification was then easily accomplished by euglobulin precipitation. Two weekly injections of 100 micrograms of this material into BALB/c mice resulted in the development of both anti-idiotypic and anti-human IgM antibodies. This system overcomes the major hurdle of generating sufficient quantities of the human idiotypic Ig to immunize and screen for specific murine antiidiotypes, and provides the material to produce these therapeutically promising reagents rapidly for clinical trials. This is, to our knowledge, the first report of a human Ig produced in mouse ascites.
The role of Ia molecules in the activation of T lymphocytes. IV. The basis of the thymocyte IL 1 response and its possible role in the generation of the T cell repertoire.
Authors: Rock K L , Benacerraf B 
Published: December 2022

Abstract
The activation requirements for thymocyte proliferation were investigated. Thymocytes proliferate in the presence of exogenous interleukin 1, which has been used as the classic assay for this factor. This response, however, is greatly decreased in cultures of purified thymic T cells. Purified thymic T cells will proliferate in the presence of IL 1 if accessory cells are added to culture. The requisite accessory cell is a non-T, adherent, radioresistant cell found in macrophage/dendritic cell-enriched fractions of both thymus and spleen. This cell bears Ia molecules, which are critically involved in the activation of thymocytes. This thymocyte-accessory cell interaction is not dependent on exogenous nominal antigens. Therefore, it appears that IL 1 allows the expansion of thymocytes with specificity for self-class II MHC antigens. This response was found to be unique to this stage of T cell development and can be observed with both mature and immature thymic T cell subsets. The implications of these findings for the physiologic expansion of self-restricted T cells in the thymus are discussed.
Allosuppressor- and allohelper-T cells in acute and chronic graft-vs-host disease. IV. Activation of donor allosuppressor cells is confined to acute GVHD.
Authors: Pals S T , Radaszkiewicz T , Gleichmann E 
Published: December 2022

Abstract
Groups of nonirradiated BDF1 mice were injected with unseparated spleen cells from B10, B10.D2, or DBA/2 donors. The diverse clinical and pathologic symptoms that developed during the course of the ensuing graft-vs-host reaction (GVHR) were related to the functional subsets of donor-T cells activated in the host. The activation of F1-specific donor T suppressor (TS) cells was confined to those GVH F1 mice that developed acute GVH disease (GVHD) (donor B10 or B10.D2). Moreover, activation in these GVH F1 mice of the Lyt-1-2+ donor TS cells sharply preceded the onset of and coincided with (week 2 to 6) the suppressive pathologic symptoms characteristic of acute GVHD, such as pancytopenia and suppression of splenic IgG production. The activation of these alloreactive TS effector cells was briefly preceded by the activation of F1-specific Lyt-1+-2- donor T helper (TH) cells and stimulation of the host's lymphoid tissue. Thus, in acute GVHD, a sequential alloactivation first of donor TH and then of TS cells was found. Those F1 mice that recovered from acute GVHD and developed stimulatory pathologic symptoms showed a concomitant loss of donor TS cell activity. An initial activation of F1-specific Lyt-1 +2- donor TH cells was also found in that parent----F1 combination (donor DBA/2), which failed to develop acute GVHD. Significantly in that combination, the alloactivation of donor TH cells was not followed by activation of significant numbers of donor TS cells. Instead, the DBA/2-injected BDF1 mice directly developed a persistent increase in splenic Ig formation and lupus-like GVHD.