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PubMed1992

Cellular determinants of age-related decrements in the T-cell mitogen response of B6CBAF1 mice.

Age-related changes in the cellular composition of the immune system that are associated with an impaired proliferative response to T-cell mitogens were identified for B6CBAF1 mice. The frequencies of precursors of Con A-induced IL-2-secreting cells (pHTL) and of Con A-induced cytotoxic cells (pCTL), determined by limiting dilution analysis, were lower for splenocytes from old mice, as were the proliferative responses to Con A and PHA, determined in conventional high cell density cultures for the same mice. The pHTL frequency correlated with the proliferative response to Con A (r2 = .94) and to PHA (r2 = .83) among old mice, but not among young; there were no correlations of pCTL frequency with proliferative responses. The reduced pHTL frequency in old mice resulted from: (a) an age-related doubling of the number of splenic B cells that diluted T cells, and (b) a 67% decline in the absolute number of Con A-reactive pHTL cells in the spleen that appeared despite the maintenance of normal numbers of total splenic CD4+ and CD8+ cells. Thus, both a decline in absolute pHTL numbers and an increase in the number of non-T cells in the spleen result in a diminished pHTL frequency that is closely linked to the impaired mitogen response observed for old B6CBAF1 mice.

Aging↗

PubMed1982

Plasmodium berghei malaria: blockage by immune complexes of macrophage receptors for opsonized plasmodia.

Immune complexes produced in vitro by mixing immune serum and soluble Plasmodium berghei antigens and immune complexes precipitated from serum of acutely infected rats blocked macrophage receptor sites for opsonized plasmodia. The immune complexes were precipitated from acute-phase serum, using polyethylene glycol, and their composition was determined by using a Raji cell immunofluorescence assay. The immune complexes contained immunoglobulin G (IgG), IgM, and malarial antigens. These results indicate that immune complexes in the serum of acutely infected animals may protect the plasmodia from the activities of macrophages.

Animals↗

PubMed1980

Lipids and carcinogenesis.

Experiments with animals and epidemiological data on human populations have provided evidence that high fat diets increase the incidence of certain types of cancer, such as breast cancer and colon cancer. High fat diets enhance mammary tumorigenesis in rats only when the fat contains a certain minimal level of essential fatty acids. Dietary fat appears to act as a promoter rather than affecting initiation of mammary tumors. It may do this by producing a more favorable environment for development and growth of tumor cells, either by changing the hormonal environment, by altering the properties of cell membranes thorugh changes in their lipid composition, or by other mechanisms, such as alterations in immune responses to tumor cells. The effect of dietary fat on colon cancer may be related to increased production and excretion of bile acids, some of which have been shown to be promoters of intestinal cancer in animals. It may be possible to utilize this knowledge of the effects of dietary fat on carcionogenesis to develop new methods for prevention and treatment of breast and colon cancer.

Carcinogens↗

PubMed1996

Biochemical alterations in macrophages by interaction with immune complexes.

The mouse peritoneal cells (MPS) were stimulated under in vitro and in vivo conditions with different compositions of bovine serum albumin (BSA)-anti BSA immune complexes (IC). The aim was to monitor the biochemical changes that may occur in macrophages and this activation was indicated by an increase in the number and protein content of the cells. The role of these complexes in inducing lysosomal hydrolases release from elicited as well as during an in vitro interaction with ICs was also studied. The insoluble immune complex at equivalence (IC-Eq) and immune complex-antibody excess (IC-Ab) registered a significant increase in number of cells and protein content as compared to soluble immune-complex antigen excess (IC-Ag) complexes. The IC elicited cells showed lesser secretory activity as compared to MPM cells stimulated in vitro. Stimulating capacity of ICs in causing hydrolase release was time and dose dependent. The complement coated complexes were the most effective in inducing enzyme release (4.5-5-fold).

Animals↗

PubMed1984

Cyclophosphamide-induced changes in the MRL-lpr/lpr mouse: effects upon cellular composition, immune function, and disease.

MRL-lpr/lpr mice develop massive lymphadenopathy with excessive proliferation of T cells and associated immune abnormalities. To examine whether to not the disease process is intrinsic and irreversible, an immunomodulatory drug, cyclophosphamide, was administered to 16-week-old, sick MRL-lpr/lpr mice. Analysis of lymph node cells by flow cytometry from injected and control MRL-lpr/lpr mice indicated that cyclophosphamide had a marked effect upon the lymphoid cellular composition. Whereas control lymph nodes had a very large number of abnormal dull Ly 1+ T cells and very few other cells, the cyclophosphamide-injected mice had normal T and B cells. The immune responses to a T-cell-dependent antigen, sheep red blood cells, and a T-cell mitogen, concanavalin A, were normalized in cyclophosphamide-injected mice as compared to controls. In addition, injected mice had prolonged survival, decreased arthritis, markedly reduced adenopathy and splenomegaly, improved renal histology, and significantly diminished autoantibody levels. This study suggests that the disease and associated immune abnormalities of MRL-lpr/lpr mice are reversible by selective elimination of the abnormal dull Ly 1+ T cells.

Animals↗

PubMed2004

High resolution analysis of cellular immune responses in resolved and persistent hepatitis C virus infection.

BACKGROUND & AIMS: Cellular immune responses are thought to play a key role in the resolution of primary HCV infection. Although it has been consistently shown that CD4+ T-cell responses are maintained in those with spontaneous resolution but lost in those with persistent infection, the role of CD8+ T-cell responses remains controversial. Previous studies have largely focused on limited HLA alleles and predefined CD8+ T-cell epitopes, and, thus, comprehensive studies remain to be performed. METHODS: To understand the composition of the immune response associated with spontaneous resolution, we comprehensively mapped CD8+ T-cell responses in 20 HLA-diverse persons with resolved HCV infection, using HCV peptides spanning the entire genome. We analyzed the magnitude, breadth, function, and phenotype using ELISpot, class-I tetramers, intracellular cytokine staining, and cytolytic assays. We studied in parallel HCV-specific responses and viral sequence variation in persistent infection. RESULTS: Responses in individuals with resolved infection were strong and broad with robust proliferation in response to antigen. Responses in those persistently infected were rarely detected ex vivo and, when present, were narrowly directed and weak. However, they also proliferated in vitro. Dominant target epitopes differed among individuals in both cohorts, despite frequently shared HLA-alleles. CONCLUSIONS: These data indicate that persisting, strong CD8+ T-cell responses are observed in the majority of persons with resolved HCV infection and provide support for strategies to boost CD8+ T-cell responses for the prevention or treatment of HCV infection but also highlight the diversity of responses that may need to be elicited to provide protection.

CD8-Positive T-Lymphocytes↗

PubMed2026

Multi-level aggregation analysis of microbiome composition and host gene expression reveals associations with systemic and local immunity.

The human gut microbiome plays a critical role in immune regulation, yet the molecular links between microbiome composition and host gene expression remain incompletely understood. We analyzed associations between host gene expression and microbiome composition in a cohort of 315 healthy individuals, integrating microarray-based gene expression data from three intestinal sites (ileum, transverse colon, and rectum) and six immune cell types with microbiome sequencing data. Using a hierarchical feature aggregation strategy combining principal component analysis, clustering, and covariate correction, we discovered significant associations primarily related to immunity. While microbial profiles were similar across the three intestinal sites, the transverse colon yielded the most "microbiome-host gene expression" associations. Among the immune cell types, CD8+ cells showed the highest number of associations. The first principal component of microbiome composition, reflecting a gradient from commensals (e.g., Ruminococcaceae and Christensenellaceae) to proinflammatory taxa ([Ruminococcus] gnavus and Lachnoclostridium), correlated with the expression of TNF-α-linked genes (HMOX1, CPI17, HSD3B2, and SLC5A1). Among individual genera, Catenibacterium abundance was associated with gene expression in both intestinal and immune cells, including negative associations with MRPS21 (related to mitochondrial function) in the transverse colon and with CD8+ gene programs related to T cell differentiation. These findings align with emerging evidence implicating mitochondrial dysfunction in intestinal inflammation. Our results identify multi-level associations between the gut microbiome and host gene expression, suggesting potential mechanisms by which microbiota shape local and systemic immunity and vice versa. The implicated genes and taxa represent candidates for experimental validation to improve understanding of host-microbiome homeostasis and its disruption in disease.IMPORTANCEThe gut microbiome and immune system are engaged in a complex interplay throughout human life. While most associative studies focus on case-control comparisons-typically examining patients with conditions such as inflammatory bowel disease or metabolic diseases-less is known about the molecular links between the microbiome and immune system in healthy individuals. In this study of a large cohort of healthy individuals, we addressed this gap by applying multiscale modeling to tackle the high dimensionality of host-microbiome data. We identified multi-level associations between microbiome composition and host gene expression in both intestinal tissues and immune cells. These findings offer a valuable reference for understanding baseline host-microbiome communication and highlight molecular candidates-such as TNF-α-related genes and mitochondrial pathways-for future experimental validation.

Humans↗

PubMed1977

Enhanced antibody responses to antigens presented on autologous erythrocytes.

On a dose basis, antigen coupled to autologous red blood cells is 1,000--10,000-fold more efficient at inducing an antibody response than the soluble form. More than one antigen can be coupled simultaneously to the same red blood cells. Under these circumstances, prior immunization with one antigen enhances the antibody response to the other antigen, provided both antigens are coupled to the same red cell. Thus, the technique of coupling antigens to red blood cells is a means of producing high-titred antisera without the use of adjuvant and also represents a useful procedure for preparing composite antigens for probing cell-cell interaction in the immune response.

Animals↗

PubMed1984

Yeast killer toxin and an immunity protein are processed from a composite precursor.

Yeast killer toxin is a secreted protein that kills sensitive cells by forming an ion-conducting channel. The toxin is synthesized as a larger composite precursor containing two toxin subunits and an immunity protein. The processing and action of this precursor and its components provide an attractive system for studying these cellular events common to eukaryotes.

Amino Acid Sequence↗

PubMed1995

Influence of steric stabilization of liposome-encapsulated hemoglobin on Listeria monocytogenes host defense.

Liposome-encapsulated hemoglobin (LEH) products are being investigated as potential blood substitutes. To determine if changes in LEH composition can modify the immune response, red blood cell substitutes based on conventional lipids containing phosphatidylinositol (LEH1) and sterically stabilized lipid vesicles containing polyethylene glycol phosphatidylethanolamine (LEH2) were tested for effects on host resistance. On Day 0, groups of 18 to 20 female CD-1 mice were given an intravenous (i.v.) infectious challenge with a 20% lethal dose of Listeria monocytogenes. Mice received a single i.v. dose of LEH1, LEH2, or albumin vehicle on Day +1 or Day -3 relative to infectious challenge. Mice dosed with LEH1 and LEH2 on Day +1 died rapidly from Listeria infection; but mice dosed with LEH2 lived significantly longer than did mice receiving LEH1. By contrast, when administered on Day -3, LEH1 had no significant effect on host immunity, while LEH2 increased susceptibility to Listeria infection. In addition, LEH1 and LEH2 both caused significant reduction of phagocytic activity as measured by rat alveolar macrophage (AM) ingestion of latex microspheres. AM incubated 4 hr with either LEH1 or LEH2 prior to addition of microspheres ingested fewer beads in a dose-dependent manner. No difference in in vitro phagocytic activity was observed between LEH1 or LEH2. The inability to differentiate LEH formulations based on in vitro phagocytic activity suggests that the in vivo Listeria infection model may be more relevant in discerning the immunotoxicity of the LEH formulations tested.

Animals↗

PubMed2005

[Research on chondrogenic differentiation and immunologic response of allogeneic mesenchymal stem cells implanted into joint cavity].

OBJECTIVE: To evaluate the cartilage formation ability of allogeneic mesenchymal stem cells implanted into sheep joint cavity without the use of immunosuppressive therapy. METHODS: Allogeneic mesenchymal stem cells (MSCs) loaded onto porous beta-tricalcium phosphate ceramic (beta-TCP) were implanted into normal sheep joint cavity. A complete mismatch between donor stem cells and recipient sheep was confirmed by mixed lymphocyte reaction assays prior to implantation. Eight weeks after implantation, the implants were taken out for histological and immunohistochemical analysis. The histological results were compared with data derived from joint cavity implantation of autologous MSCs-ceramic composites and cell-free ceramics. The systemic immune response was evaluated by the analysis of recipient serum for production of antibodies against allogeneic cells. RESULTS: For implantation with allogeneic MSCs, no sign of adverse immune response was detected. Histologically, few inflammation cells infiltration occurred and no antibodies against allogeneic cells were detected. Neocartilage formation in implants loaded with either allogeneic or autologous mesenchymal stem cells was revealed by histochemical and immunohistochemical analysis. In implants without stem cells, no cartilage formation was detected. CONCLUSIONS: Allogeneic mesenchymal stem cells are capable of forming cartilage under the effect of joint cavity environment. Without the use of immunosuppressive therapy, allogeneic MSCs do not provoke an adverse immune response in vivo.

Animals↗

PubMed2006

Right on the spot. Chemokine triggering of integrin-mediated arrest of rolling leukocytes.

The arrest of rolling leukocytes on various target vascular beds is crucial for their recruitment at inflammatory sites and secondary lymphoid tissues. Leukocyte arrest is predominantly mediated by integrins interacting with either constitutive or inducible endothelial ligands. Integrins are cytoskeletally regulated heterodimers maintained in largely low affinity conformational states on circulating leukocytes. For arrest to occur, the affinity of integrin heterodimers must be enhanced in situ upon leukocyte encounter with proper endothelial-displayed chemokines or chemoattractants which bind and signal through specific G-protein coupled receptors (GPCRs) on the leukocyte surface. Recent studies suggest that this integrin activation involves rapid conformational alterations locally induced at confined leukocyte-endothelial contact sites. Following binding, integrin microclustering reinforced by associations with the cortical actin cytoskeleton further enhances integrin-mediated adhesiveness under shear stress. These events are controlled by complex signaling events, involving a series of small GTPases, as well as protein and lipid kinases which are triggered by chemokine bound GPCRs. To rapidly mediate this specialized function, subsets of signaling proteins and their specific targets are thought to preexist in pre-assembled multi-molecular complexes or signalosomes. Recent in vitro dissection of chemokine-triggered integrin activation on lymphocytes and neutrophils suggests that these signalosomes may vary both in composition and mode of activity between different immune cell types and distinct integrins. We review in this article recent findings on key elements implicated in chemokine triggering of integrin activation on rolling leukocytes, and discuss the possible existence of preformed proadhesive signaling networks in different subsets of leukocytes.

Animals↗

PubMed1999

Immune complex size and complement regulate cytokine production by peripheral blood mononuclear cells.

We have previously shown that immune complexes isolated from children with juvenile rheumatoid arthritis are heterogeneous in their size, composition, and proinflammatory capacities. The experiments described here were undertaken to clarify further the roles of size and composition in determining the proinflammatory effects of immune complexes. We incubated peripheral blood mononuclear cells (PBMCs) with different soluble immune complex preparations: opsonized complexes, which were formed in the presence of serum, unopsonized complexes, which were formed in the absence of serum, and immune precipitates solubilized by complement after their formation. ELISA assays showed that immune complexes formed in the presence of complement were less efficient than unopsonized complexes in inducing IL-1beta and IL-8 secretion from leukocytes. Solubilized immune precipitates showed intermediate capacity to stimulate the release of both cytokines. Complexes formed in heat-inactivated serum were as efficient as unopsonized complexes in eliciting cytokine secretion from the cells. The capacity of complement to regulate cytokine secretion from leukocytes was related, at least in part, to immune complex size. Sucrose density gradients showed unopsonized complexes and solubilized immune precipitates were larger than opsonized immune complexes. In contrast, fluid-phase binding of C4 to immune complexes, which did not appreciably change immune complex size, substantially increased IL-1beta secretion from PBMC.

Antigen-Antibody Complex↗

PubMed2003

Transcription cooperation by NFAT.C/EBP composite enhancer complex.

The nuclear factor of activated T cells (NFAT) group of transcription factors regulates gene expression in immune and non-immune cells. NFAT-mediated gene transcription is orchestrated, in part, by formation of a composite regulatory element. Here we demonstrate that NFAT interacts with transcription factor CCAAT/enhancer-binding protein (C/EBP) to form a composite enhancer complex, to potentiate expression of the peroxisome proliferator-activated receptor-gamma2 gene. Formation of a ternary NFAT.C/EBP.DNA complex is required for the transcriptional cooperation. A similar NFAT.C/EBP composite element is found in the regulatory region of the insulin-like growth factor 2, angiotensin-converting enzyme homolog, and transcription factor POU4F3 genes. Thus, the NFAT.C/EBP composite element represents a novel regulatory enhancer to direct NFAT-mediated gene transcription.

Binding Sites↗

PubMed1998

Infection with classical swine fever virus: effects on phenotype and immune responsiveness of porcine T lymphocytes.

T lymphocytes obtained from pigs infected with a lethal dose of classical swine fever virus were analysed for phenotypic changes in the composition of T-cell subpopulations and for alterations in their immune responsiveness in vitro during the course of disease. Viral antigen detected in all subpopulations and the selective depletion of CD4- CD8- gamma/delta T cells showed that peripheral blood T lymphocytes were affected in the terminal stage (14-19 days post-infection) of classical swine fever whereas no implications for T lymphocytes were obvious during the first 10 days after infection. Furthermore, a depletion of CD1+ CD4+ CD8+ 'common thymocytes' was characteristic for the infected animals. Studies on immune functions of peripheral T lymphocytes revealed an abrogation of cellular immune responses as early as 3-5 days after infection and thus before detection of viral antigens in these cells. The data suggest that early immunosuppression represents a crucial event for the manifestation of classical swine fever.

Animals↗

PubMed1996

A novel Escherichia coli lipid A mutant that produces an antiinflammatory lipopolysaccharide.

A unique screen was used to identify mutations in Escherichia coli lipid A biosynthesis that result in a decreased ability to stimulate E-selectin expression by human endothelial cells. A mutation was identified in the msbB gene of E. coli that resulted in lipopolysaccharide (LPS) that lacks the myristoyl fatty acid moiety of the lipid A. Unlike all previously reported lipid A mutants, the msbB mutant was not conditionally lethal for growth. Viable cells or purified LPS from an msbB mutant had a 1000-10,000-fold reduction in the ability to stimulate E-selectin production by human endothelial cells and TNF alpha production by adherent monocytes. The cloned msbB gene was able to functionally complement the msbB mutant, restoring both the LPS to its native composition and the ability of the strain to stimulate immune cells. Nonmyristoylated LPS acted as an antagonist for E-selectin expression when mixed with LPS obtained from the parental strain. These studies demonstrate a significant role for the myristate component of LPS in immune cell activation and antagonism. In addition, the msbB mutant allowed us to directly examine the crucial role that the lipid A structure plays when viable bacteria are presented to host defense cells.

Acyltransferases↗

PubMed1998

Peripheral blood versus bone marrow for hematopoietic cell transplantation.

Peripheral blood stem cell transplantation is being used more frequently in both the autologous and allogeneic setting. The use of cytokines either alone or in conjunction with chemotherapy priming has made peripheral procurement of the stem cells through apheresis possible. Differences exist both in the composition of the graft and in subsequent posttransplantation immune reconstitution between peripheral blood stem cells and bone marrow. Reliable estimates of the comparative incidence of acute and chronic graft-versus-host disease following blood or marrow allogeneic transplantation are not yet available.

Blood Cells↗

PubMed1997

Early changes in the phenotypic composition of lymphocytes in the bronchoalveolar lavage of pigs after aerogenic immunization with Pasteurella multocida aerosols.

The phenotypic composition of bronchoalveolar lymphocytes (BALL) of healthy untreated pigs and of pigs immunized via aerosol with a live Pasteurella multocida mutant was measured cytofluorometrically in comparison to blood lymphocytes (PBL). Cells were analyzed using monoclonal antibodies against porcine IgM, IgA, IgG and SWC3 in single-colour fluorescence and the following antibody combinations for two-colour fluorescence: CD2/SWC1, SWC1/CD25 and CD4/CD8. In nonimmunized pigs, differences between lymphocyte subsets derived from blood and lung were obvious. The numbers of CD2-SWC1+ T-cells, CD25+ activated lymphocytes and IgG+ cells were significantly higher in the bronchoalveolar compartment. Aerosol immunization with P. multocida caused only insignificant changes in the phenotypic composition of PBL whereas the composition of lung-derived lymphocytes changed markedly. The percentage of CD2-SWC1+ lymphocytes and of CD25+ cells coexpressing the SWC1 antigen in BALL increased up to 10 days after aerosol administration, whereas the percentage of all Ig+ cells decreased. These data reflect an early cellular reaction to an aerogenic immunization with a P. multocida aerosol, characterized by an increase in CD2+ T-cells and a T-cell activation.

Aerosols↗