Characteristics of complement receptor-bearing cells in the spleens of tumor-bearing mice.

In the course of mammary tumor development, a population of nylon nonadherent cells with CR appears in the spleens of tumor-bearing mice although none are ever detected in normal mice. These cells apparently arise in response to immunologic stimulation. In a series of studies we have further characterized subsets of T cells (CR+ and CR-) with regard to their responses to mitogens in the lymphocyte transformation assay. Nylon column nonadherent cells from the spleens of tumor-bearing mice were rosetted in a complement receptor assay using EAC rosetting, and CR+ cells were separated from CR- by centrifugation in a discontinuous Ficoll gradient. CR+ T cells responded strongly to PHA and Con A and in addition responded to LPS, an activity not usually associated with conventional T cells. In contrast, CR- T cells from tumor-burdened mice responded to PHA but failed to respond to Con A or LPS.     

IgG Fc receptor-bearing cells during early lymphoid cell development in the chicken

Cells from intraembryonic mesenchyme, yolk sac, bursa of Fabricius, and thymus from chicken embryos at different stages of development were studied for the presence of IgG Fc receptors by EA-rosette formation and binding of heat-aggregated chicken IgG (agg IgG). Cells with Fc receptors were found in high frequency in the intraembryonic mesenchyme as early as on the third day of incubation, in the yolk sac on the 7th day, in the bursa on the 10th day, and in the thymus on the 16th day of embryonic development. In the bursa the number of agg IgG binding cells increased with the age of the embryo and remained high after hatching, whereas in the thymus the peak value (76%) was observed on the 16th embryonic day, and after hatching only about 10% of the cells expressed the agg IgG receptors. The results also suggest that the appearance of IgG Fc receptors precedes the expression of B-L (Ia-like) antigens and of cytoplasmic and surface immunoglobulins on early lymphoid cells of the chicken embryo.     

Catecholamines induce an increase in nerve growth factor content in the medium of mouse L-M cells

L-M cells, a mouse fibroblast cell line, synthesized and secreted a nerve growth factor (NGF). The neurite outgrowth stimulatory activity, immunoreactivity, molecular weight, and isoelectric point of L-M cell NGF were identical to those of beta-NGF of the mouse submaxillary gland. Treatment of the cells with either norepinephrine or epinephrine in the range of 0.05-0.2 mM for 24 h resulted in a 3-20-fold increase in NGF content in the medium of the L-M cells. The NGF of epinephrine-treated cell was identical to that of control cell. The stimulation of the increase in NGF content was observed after a 4-h lag time. The rate of incorporation of [3H]leucine into trichloroacetic acid-insoluble materials was essentially unchanged during the treatment. These results suggested that norepinephrine and epinephrine stimulated the de novo synthesis and secretion of NGF protein. Evidence is also presented to indicate that the effects of the drugs are due to the catechol part of the molecule and not mediated by adrenergic receptors.     

External signals can induce stable increase in frequency of cell death in populations

Relatively weak radiation and some other external actions, producing no "forced" cell death, trigger some intracellular mechanisms in various unicellular organisms (amoebae, ciliates, yeasts) and in the studied mammalian cells (rat vascular endotheliocytes). These mechanisms provide spasmodic changes: massive transition of cell populations into a stationary alternative state which is characterized by an increased predisposition to cell death, in comparison with the initial level. This phenomenon is considered as a particular, widely spread in nature form of genetic control of cell death frequency populations.     

In-vivo effects of lipopolysaccharide on lymphoid and non-lymphoid cells in the mouse spleen

In mice marginal metallophils are located at the periphery of the white pulp along the inner border of the marginal sinus. These cells have a weak phagocytic capacity but their function is still unclear. In the present study evidence is given that marginal metallophils migrate from the periphery of the follicle towards the follicle centres after administration of at least 7 micrograms lipopolysaccharide (LPS). This migration is most significant after 24 and 48 h and appears to be a specific effect of LPS. In the follicle centre marginal metallophils take up cell debris and may become tingible body macrophages. The similarity between these two cell types is discussed. The possible effects of several other polyclonal B-cell mitogens on marginal metallophils have also been studied. Dextran sulphate also induces migration of marginal metallophils but this compound triggers a migration and accumulation of these cells at the periphery of the follicles.     

Corticotropin-releasing factor receptor 1 in mouse spleen: expression after immune stimulation and identification of receptor-bearing cells

A specific polyclonal Ab against the N-terminal domain of corticotropin-releasing factor (CRF) receptor, type 1 (CRF-R1), was employed to an immunohistochemical analysis of the spleen from naive mice and mice exposed to an immune challenge. Cell types stained with anti-CRF-R1 Ab were identified by their nuclear shapes and colocalization with the cell type-specific markers ER-MP58, ER-MP20, Moma-1, Moma 2, anti-CD3e mAbs, and anti-Ig Ab. Only a few clusters of CRF-R1+ cells were found in spleen sections of naive mice at sites typical for granulopoietic islands. However, a 17-fold increase in the mean number of CRF-R1+ cells was noted within hours following a challenge of acute systemic inflammation induced by i.p. administration of LPS. The majority of these cells were identified as mature neutrophils. CRF-R1 was shown to mediate suppression of the IL-1beta secretion by these cells. However, at later time points a large number of granulocyte-macrophage precursors was strongly labeled with anti-CRF-R1 Ab. Western blot analysis of splenic membranes from animals treated with LPS revealed a m.w. of approximately 70,000 for CRF-R1. Subcellular staining patterns were suggestive for the predominant localization of CRF-R1 on granule membranes. CRF-R1 mRNA was detected in spleen but not in bone marrow and peripheral blood leukocytes from naive mice. Thus, it was indicated that CRF-R1 was not produced constitutively by mature or immature neutrophils. Its production was rather triggered by inflammatory stimuli.     

Antigen binding to lymphoid cells from unimmunized mice: high frequency of beta-galactosidase binding cells at optimal conditions

The median frequency of antigen-binding cells for beta-galactosidase in mouse organs is: thymus—0.1%; lymph nodes—0.35%; spleen 2.0%; bone marrow—4.8%. We propose that these frequencies closely approximate the actual numbers of cells bearing receptors with beta-galactosidase specificity.We attribute these relatively high frequencies to (a) incubation of cells with saturating concentrations of antigen, (b) the multimeric nature of beta-galactosidase, and (c) retention of receptors by fixation.Several types of artifactual binding of beta-galactosidase were excluded from major consideration: “sticky cells;” GZ substrates on cell surfaces; spreading of histochemical reaction product; nonimmunoglobulin-related binding.We conclude that the high frequency of antigen binding cells found in this and other current studies is inconsistent with a model of unispecificity in precursor cells of either the T or B cell lines.     

Immunologic tolerance to HGG in mice. I. Suppression of the HGG response in normal mice with spleen cells or a spleen cell lysate from tolerant mice.

Adoptive transfer of spleen cells or spleen cell lysates from mice tolerant to human-gamma-globulin (HGG) specifically suppressed the response of normal syngeneic recipients to HGG. The suppressive activity could be transferred for over 100 days after tolerance induction. The suppression induced by both spleen cells and spleen cell lysate was found to be specific as evidenced by a normal response to a challenge with turkey-gamma-globulin or goat erythrocytes. The activity of the suppressive lysate could be removed by passing the material through an HGG immunoadsorbent column but not by passing it through an anti-HGG column or a BSA column. These results indicated that the factor had antigen specificity and was probably not antigen-antibody complexes. That this suppression was not due to a shifting of the kinetics of the antibody response has also been demonstrated. The antigen-specific suppressor factor in the tolerant spleen cell lysates was a protein with a m.w. of approximately 45,000 daltons. The kinetics of the appearance of both suppressor cells and suppressor factor were consistent with a mechanism of active suppression functioning in the maintenance of tolerance to HGG.     

Ultrastructural studies of C1300 neuroblastoma cell interaction with syngeneic spleen lymphoid cells.

Sensitized and unsensitized spleen lymphoid cells from A/J mice were induced to form rosettes with cells of clone NB6R of syngeneic C1300 neuroblastoma cells. Light and transmission electron microscopy were applied in combination with ⁵¹Cr release experiments to follow the time course of reaction after rosette formation. With unsensitized lymphoid cells, rosettes formed but target cell morphology in general remained unchanged. With sensitized lymphoid cells a progressive series of morphological changes in the target cells was seen, initially in the mitochondria and, later, when specific ⁵¹Cr release became significant, in the formation of large surface blebs and protrusions. Our data also show another phenomenon occasionally following rosette formation. Lymphocytes were seen within the target cell; these either apparently transformed to lymphoblasts and killed the target cell from the inside or alternatively were destroyed by the host cell and their material was reutilized.     

Helicobacter pylori-pulsed dendritic cells induce H. pylori-specific immunity in mice

Background: The growing concern over the emergence of antibiotic‐resistant Helicobacter pylori infection is propelling the development of an efficacious vaccine to control this highly adaptive organism. Aim: We studied the use of a dendritic cell (DC)‐based vaccine against H. pylori infection in mice. Methods: The cellular immune responses to murine bone marrow‐derived DCs pulsed with phosphate‐buffered saline (PBS‐DC) or live H. pylori SS1 (HP‐DC) were assessed in vitro and in vivo. The protective immunity against H. pylori SS1 oral challenge was compared between HP‐DC or PBS‐DC immunized mice. The effect of regulatory T‐cell (Treg) depletion by anti‐CD25 antibody on HP‐DC vaccine efficacy was also evaluated. Results: HP‐DC induced a Th1‐dominant response in vitro. In vivo, HP‐DC immunized mice were characterized by a mixed Th1/Th2 peripheral immune response. However, in the stomach, HP‐DC immunized mice expressed a higher level of IFN‐γ compared to PBS‐DC immunized mice; no difference was found for interleukin‐5 expressions in the stomach. A lower bacterial colonization post‐H. pylori challenge was observed in HP‐DC immunized mice compared to PBS‐DC immunized mice with no significant difference in gastritis severity. H. pylori‐specific Th1 response and protective immunity were further enhanced in vivo by depletion of Treg with anti‐CD25 antibody. Conclusion: DC‐based anti‐H. pylori vaccine induced H. pylori‐specific helper T‐cell responses capable of limiting bacterial colonization. Our data support the critical role of effector cellular immune response in the development of H. pylori vaccine.     

In vivo effects of lipopolysaccharide on lymphoid and non-lymphoid cells in the mouse spleen

Summary In the present study the effects of lipopolysaccharide (LPS) on the cellular composition and phagocytosis of India ink in the inner parts of the periarteriolar lymphocyte sheaths (PALS) are described.Staining for B-, T-lymphocytes, and reticulin fibers in the spleen of normal and LPS-injected mice shows that the B-dependent follicular area is increased in size after LPS administration. However, the number of T-lymphocytes in the inner PALS is reduced markedly and a relatively high number of B-lymphocytes can be found in this area. The significance of this phenomenon is discussed.In untreated mouse spleen, carbon particles become localized in strongly acid-phosphatase (AP)-positive macrophages of the red pulp, marginal zone and white pulp 24 h after an intravenous injection of India ink. All these macrophages contain numerous carbon particles. After LPS pretreatment, the phagocytosis of carbon particles in the inner PALS is dramatically diminished, although many strongly AP-positive macrophages can be found in this area. The phagocytosis of carbon particles in the other compartments of the spleen did not change. It appears that injection of 2 g LPS or more is sufficient to induce this phenomenon which is most significant when LPS is injected 24 or 48 h before exposure to India ink.Abbreviations LPS lipopolysaccharide - PALS periarteriolar lymphocyte sheath - AP acid phosphatase - IDC interdigitating cells     

Attenuation of interleukin 2 signal in the spleen cells of complex ganglioside-lacking mice.

T cell development and function in complex ganglioside-lacking (GM2/GD2 synthase gene-disrupted) mice were analyzed. GM1, asialo-GM1, and GD1b were representative gangliosides expressed on T cells of the wild type mice and completely deleted on those of the mutant mice. The sizes and cell numbers of the mutant mice spleen and thymus were significantly reduced. Spleen cells from the mutant mice showed clearly reduced proliferation compared with the wild type when stimulated by interleukin 2 (IL-2) but not when treated with concanavalin A or anti-CD3 cross-linking. Expression levels of IL-2 receptor alpha, beta, and gamma were almost equivalent, and up-regulation of alpha chain after T cell activation was also similar between the mutant and wild type mice. Activation of JAK1, JAK3, and SAT5 after IL-2 treatment was reduced, and c-fos expression was delayed and reduced in the mutant spleen cells, suggesting that the IL-2 signal was attenuated in the mutant mice probably due to the modulation of IL-2 receptors by the lack of complex gangliosides.