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Biomedical subjects

C A Chambers

Publications and source records attributed to C A Chambers.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effect of Mycoplasma arthritidis superantigen on enzymatically induced arthritis in mice.

The objective of this study was to examine the effect of the stimulation of the immune system with Mycoplasma arthritidis superantigen (MAS) on joint inflammation and cartilage destruction. MAS was administered either alone or combined with a model of degenerative arthritis induced by intraarticular injection of collagenase enzyme. Intraperitoneal injection of MAS resulted in activation of peripheral lymphocytes in BALB/c mice, as shown by a proliferative response of splenocytes isolated from MAS-treated animals to IL-2-containing supernatant. Intraperitoneal or intra-articular administration of MAS alone at concentrations maximally activating lymphocytes had no detectable effect on joints. Intra-articular injection of collagenase resulted in some infiltration of inflammatory cells into the joints, hyperplasia and hypertrophy of synovial lining, pannus formation and surface loss of proteoglycans 7 days following the injection. At 21 days, the animals showed almost total loss of cartilage and minimal or no inflammation. Animals receiving MAS in addition to collagenase treatment showed similar changes in the joints. These data have demonstrated that activation of the immune system with MAS in vivo does not increase joint inflammation or cartilage degradation in enzymatically induced arthritis.

Animals↗
PubMed1994

Conserved amino acid residues in the complementarity-determining region 1 of the TCR beta-chain are involved in the recognition of conventional Ag and Mls-1 superantigen.

Superantigens activate T cells by interacting primarily with the V beta region of the TCR. This report describes a series of studies performed to elucidate the role of the conserved amino acid motif (Asp-His-Asn) in the complementarity-determining region 1 (CDR1) of the TCR V beta chains that recognize murine endogenous superantigen Mls-1. By using site-directed mutagenesis of the Mls-1-reactive TCR V beta 6 gene, it is shown that the alterations of the conserved CDR1 motif disrupt Mls-1 superantigen and conventional Ag recognition in vitro. The loss of V beta 6 (mutant)+ TCR reactivity to Mls-1 superantigen is apparently dependent on the partner alpha-chain in the V beta 6/V alpha 3 TCR pairing shows some reactivity to Mls-1, whereas other TCR pairings do not. The examination of the developmental fate of the mutated form of the V beta 6 chain in Mls-1+ mice by using retroviral vector-mediated gene transfer confirms the critical role played by the CDR1 residues in Mls-1 recognition in vivo. Collectively, the results indicate that the CDR1 of the TCR V beta 6 chain is involved in interacting with peptide/MHC as well as in Mls-1 recognition. The observation that the conserved residues in selective TCR V beta chains are imparting a significant contribution to Ag recognition suggests a molecular basis for the intrinsic bias of some V beta chains for MHC molecules.

Amino Acid Sequence↗
PubMed1994

Expression of the NK-TR gene is required for NK-like activity in human T cells.

NK cells lyse target cells without previous immune sensitization. A small subset of T cells also exhibits NK-like activity, which is distinct from TCR-mediated, MHC-restricted, and MHC-unrestricted cytotoxicity. We recently cloned a gene, NK-TR, which is postulated to be part of the NK target-recognition/triggering complex. To determine whether the NK-TR gene product is requisite for NK-like killing, stable antisense transfectants were generated by using a human T cell clone with NK-like activity. Two distinct antisense regions of the sequence were used to generate the transfectants alpha NK-TR and alpha Cyclo. Transfectants lost the ability to lyse NK-sensitive targets but did not lose lectin-mediated cytotoxic activity. This effect was not seen with the control vector transfectant cell line. The loss of NK-like activity by the antisense transfectant alpha NK-TR correlated with the specific decrease in endogenous NK-TR mRNA and protein. These results demonstrate the requirement for the NK-TR protein for NK-like killing. Moreover, the results have important implications for examining developmental relationship between T and NK cells and the possible roles for T cells with NK-like activity in vivo.

Base Sequence↗
PubMed1994

High level functional engraftment of severe combined immunodeficient mice with human peripheral blood lymphocytes following pretreatment with radiation and anti-asialo GM1.

The severe combined immunodeficient (SCID) mouse engrafted with human peripheral blood lymphocytes (PBLs) is a potentially useful model for the study of cancer immunotherapy. For this application, rapid, consistent, and high level engraftment of SCID mice with functional human cytotoxic effector cells is necessary. To date, short term human lymphoid cell engraftment in SCID mice has generally been low and variable. Further, most of the human cells detected within the first 30 days are found in the peritoneal cavity. The purpose of the present study was to improve short term reconstitution of human PBLs in the SCID mouse. When untreated SCID mice were injected with human PBLs, the mean level of CD3+ cells in the spleens was < 5% on days 6-32 after injection, as determined by flow cytometry (FCM). Depletion of SCID mouse natural killer (NK) cells with anti-asialo GM1 only marginally improved short term reconstitution with human CD3+ cells. Preirradiation of SCID mice with 3 Gy improved reconstitution to over 16% CD3+ cells on days 12-14 following engraftment. However, the combination of pretreatment with anti-asialo GM1 plus radiation, significantly increased the mean percentage of human CD3+ cells in the spleen to 40% within 2 weeks following injection of PBLs. Human T cells positive for CD4, CD8, TcR alpha beta, and TcR gamma delta, and human NK and B cells were detected in the spleens of irradiated plus anti-asialo GM1 pretreated SCID mice. The presence of human lymphoid cells was confirmed by immunohistologic staining. The human immune cells in these mice were shown to be functional by the in vivo demonstration of an appropriate secondary immune response to the injection of tetanus toxoid and by an in vivo proliferative response to phytohemagglutinin. Human NK cells could be found in the spleens and peripheral blood of irradiated plus anti-asialo GM1 pretreated mice. These cells were also shown to be competent by their ability to lyse the human NK sensitive tumor targets K562 and MOLT-4 in 51Cr release assays. Thus, pretreatment of SCID mice with radiation plus anti-asialo GM1 significantly improves short term human PBL engraftment and provides a potentially useful model for the study of cancer immunotherapy.

Animals↗
PubMed1994

Exogenous Mtv-7 superantigen transgene expression in major histocompatibility complex class II I-E- mice reconstituted with embryonic stem cell-derived hematopoietic stem cells.

Direct genetic manipulation of hematopoietic cells is limited by the lack of an established hematopoietic stem cell line. It has been demonstrated that embryonic stem (ES) cell<-->tetraploid embryos are completely ES cell-derived and that fetal liver (FL) cells from these embryos support hematopoiesis in lethally irradiated recipients. In this report, we demonstrate that FL cells from ES cell<-->tetraploid embryos support normal lymphopoiesis and T-cell repertoire development. Moreover, the introduction of the Mtv-7 superantigen transgene coding for minor lymphocyte stimulatory antigen 1 into murine hematopoietic cells via reconstitution with ES cell<-->tetraploid FL cells demonstrates that this method can effectively confer stable genetic changes into the hematopoietic tissues without going through the germ line. Long-term and secondary reconstitution with ES cell<-->tetraploid FL cells expressing the Mtv-7 superantigen transgene clonally deleted minor lymphocyte stimulatory antigen 1-reactive T-cell receptor V beta 6+, -8.1+, and -9+ T cells, but not V beta 7+ T cells, in H-2b (I-E-) mice. This model system will be extremely important for analyzing structure-function relationships of molecules involved in proliferation, differentiation, and selection of hematopoietic cells in vivo and for examining hematopoiesis-specific effects of mutations that are lethal during embryogenesis.

Animals↗
PubMed1994

TKO'ed: lox, stock and barrel.

The generation of panels of mutant mice by homologous recombination has greatly increased the ability to assess the function of particular gene products in vivo. The ability to control the developmental stage, the tissue and the nature of the mutation would be an important innovation. A recent report demonstrates that the conservative site-specific recombination of bacteriophage P1, namely Cre-lox, can be used successfully in combination with homologous recombination to generate temporal- and cell-restricted mutations in vivo. This technical advance allows a greater flexibility in gene targeting and will have a significant impact on how complex gene functions are studied in vivo.

Animals↗
PubMed1992

Long term expression of IL-4 in vivo using retroviral-mediated gene transfer.

Th cell subsets regulate immune responses by cell-cell interaction and secretion of cytokines. IL-4 is one of the cytokines secreted by Th cells important for cellular and humoral, particularly IgG1 and IgE responses. To study the role of IL-4 in T cell development and regulation of immune responses in vivo, low IgE-responder C57BL/6 mice were reconstituted with bone marrow cells that had been infected with recombinant retrovirus expressing a high level of IL-4. The reconstituted mice expressed retroviral IL-4 transcripts (9/10) even 8 mo postreconstitution. Physiologically significant levels of IL-4 were detected in the majority of the provirus-positive animals tested (5/8). Ectopic expression of exogenous IL-4 in hematopoietic cells had dramatic effects on T cell development resulting in changes in CD4:CD8 ratios. Moreover, the levels of serum IgG1 and, with antigenic stimulation, IgE were also increased. These results demonstrate that the retrovirus gene transfer system can be used to study the effects of ectopic cytokine gene expression in vivo on Ig isotype regulation and T helper cell subset differentiation.

Animals↗
PubMed1992

Ectopic lymphokine gene expression in human peripheral blood lymphocytes in vivo.

An animal model to study the effects of ectopic expression of cytokines involved in cell growth and differentiation has been established. Retrovirus vectors containing the human interleukin 6 cDNA were used to produce high titer virus-producing lines. Human peripheral blood lymphocytes (hPBLs) were successfully infected with the retrovirus and engrafted into severe combined immunodeficient mice. The majority of the animals were engrafted with hPBLs, as determined by the presence of human glucose phosphate isomerase. Furthermore, six of seven mice engrafted with hPBLs infected with high titer virus and detectable hPBLs present in the spleen expressed the retroviral human interleukin 6 gene. Importantly, human interleukin 6 protein was expressed at physiologically significant levels in these mice. These results demonstrate that models for human disease and immunotherapy involving retrovirus-mediated gene transfer into human cells can be developed in mice.

Animals↗
PubMed1992

Functional heterogeneity of human T cell clones from atopic and non-atopic donors.

Several distinct T helper (TH) subsets have been identified, based on the cytokines secreted. Recently, it has been demonstrated that these subsets can regulate the isotype of humoral responses. To investigate the possible differences in TH subsets between atopic donors which have elevated serum IgE and donors with normal serum IgE, we examined series of human TH cell clones. A total of 31 and 22 CD4+ T cell clones from the atopic and non-atopic donors, respectively, were characterized for the ability to help for IgE synthesis in vitro. T cell clones generated with allergen AgE from the atopic donor were autoreactive and all induced IgE synthesis. Tetanus toxoid-specific (TT) and phytohaemagglutinin clones were generated from both donors. There was significant heterogeneity between the T cells isolated with different stimuli from the same atopic donor. Also, there was a significant difference in the number of T cells generated from the atopic versus the non-atopic donor which helped for IgE, although there was no significant difference between the total number of T cells able to help for immunoglobulin synthesis of other isotypes. Most importantly, there was a higher frequency of clones able to support IgE synthesis between TT-specific T cell clones generated from the atopic versus the non-atopic donor. These results suggest that there are changes in subsets of TH cells specific for microbial antigens as well as allergens in atopics, which may have important implications for the aetiology of atopic disease.

Clone Cells↗
PubMed1990

A multigene deletion in the immunoglobulin heavy chain region in a highly atopic individual.

Highly atopic individuals, with marked allergy, have extremely elevated total plasma IgE levels. To determine if atopy could be associated with structural alterations involving the IGHE gene of the immunoglobulin heavy chain constant region, the genomic DNA from five atopic individuals was examined. We describe here the identification of a deletion of approximately 120kb, including the IGHA1, IGHGP, IGHG2, AGHG4, and IGHE genes of the IGH constant region, in one atopic patient. This deletion arose de novo from a maternally derived chromosome. The deletion, although apparently not the primary cause of the atopic phenotype of this patient, could be indirectly responsible for the phenotype by exposing aberrant immunoglobulin-regulating elements within the paternally derived IGH constant region.

Adolescent↗
PubMed1986

Type VI collagen and glycoprotein MFPI are distinct components of the extracellular matrix.

Two collagenous glycoproteins, Mr 140,000 and Mr 150,000, are synthesized and secreted into the medium of cultured fibroblasts. The glycoprotein of Mr 140,000 is identical with the 140K(VI) component of type VI collagen by both immunological and physicochemical criteria. The glycoprotein of Mr 150,000 is immunologically distinct and exhibits the physicochemical characteristics of the putative elastic microfibrillar glycoprotein MFPI.

Animals↗
PubMed1985

Isolation from bovine elastic tissues of collagen type VI and characterization of its form in vivo.

Foetal-bovine nuchal ligament and aorta, together with adult-bovine aorta and pregnant uterus, were extracted under dissociative conditions in the absence and in the presence of a reducing agent. A collagenous glycoprotein of Mr 140000 [designated component 140K(VI)], identified in these extracts as the major periodate/Schiff-positive component, was shown to be related to collagen type VI. Digestion of non-reduced extracts with pepsin yielded periodate/Schiff-positive peptides that, on the basis of their electrophoretic mobilities, amino acid analyses and peptide 'maps', were identical with type VI collagen fragments prepared by standard procedures. It is concluded that collagen type VI occurs in vivo as molecule comprising three chains of Mr 140000 in which the helical domains account for about one-third of each polypeptide. Biosynthetic experiments with nuchal-ligament fibroblasts in culture demonstrated that a bacterial-collagenase-sensitive [3H]fucose-labelled glycoprotein, Mr 140000, was immunoprecipitated from culture medium by a specific antibody to the pepsin-derived form of collagen type VI. This result suggests that the collagenous polypeptides [140K(VI) components] represent the biosynthetic precursors of type VI collagen that do not undergo processing to smaller species before deposition in the extracellular matrix. Analyses of 5M-guanidinium chloride extracts of tissues with markedly different elastin contents and at different stages of development suggested that there was no relationship between collagen type VI and elastic-fibre microfibrils, a conclusion supported by the observation that the immunoprecipitated glycoprotein, Mr 140000, was distinct from the glycoprotein MFPI, Mr 150000, believed to be a constituent of these microfibrils [Sear, Grant & Jackson (1981) Biochem. J. 194, 587-598].

Amino Acids↗
PubMed1984

Collagen heterogeneity and quantification in developing bovine nuchal ligament.

The collagenous components were investigated in peptic digests of developing bovine nuchal ligament. Types I and III collagen were the major species isolated, but the presence of types IV, V and VI was also shown. Changes in the pepsin-susceptibility of nuchal ligament during foetal development were observed. CNBr-cleavage peptide analysis indicated that type I collagen became cross-linked rapidly, as evidenced by the lack of alpha 1(I)CB6. At present it is not clear if this decrease in pepsin-susceptibility is due to cross-linking of collagen, to increased deposition of elastin, or to both. Quantification of collagen types I and III was shown to depend on the method used. When pepsin-solubilized material was examined an apparent increase in type III collagen with respect to foetal age was observed, whereas when CNBr digests of intact ligament were examined a relatively constant amount of type III collagen (approx. 24%) was found. The constant amount of type III collagen observed during foetal development changed at birth and increased in mature nuchal ligament to represent approx. 45% of the total collagen.

Amino Acids↗
PubMed1982

The effect of digoxin on the response to lithium therapy in mania.

Patients suffering from manic-depressive psychosis, manic type (ICD 296.0), were treated with lithium carbonate and randomly allocated to two groups, one received digoxin and the other matching placebo for 7 days. Severity of mania was rated by psychiatrists on the Manic Rating Scale and Analogue Line on days 0 and 7 and by nurses daily on the Hargreaves Rating Scale, Psychotic Rating. Fourteen patients received digoxin and lithium carbonate and 14 patients received placebo and lithium carbonate. Improvement in the placebo lithium group was significantly greater than that in the digoxin lithium group. This trial suggests, therefore, that the effect of inhibition of membrane cation carrier is to reduce the response to lithium. This result is in keeping with our hypothesis that an increase in Na-K ATPase is essential to the therapeutic effect of lithium carbonate. It does not, however, exclude the possibility that the observations resulted from the inhibition by digoxin of lithium entry into the brain.

Adult↗
PubMed1981

Immunologic control of the ascites form of murine adenocarcinoma 755. III. Efficacy of serum therapy is controlled by a single genetic locus.

We have previously described a passive serum therapy system in which potent protection against challenge of syngeneic mice with large doses (10(4) X LD100) of AD755a tumor cells can be accomplished by administration of as little as 2 to 5 microliters/mouse of hyperimmune anti-tumor cell serum. The present results demonstrate that the efficacy of the serum protection effect is strain-dependent and is under the control of a single genetic locus, denoted ADP-1. Through a series of crosses between highly protected C57BL/6J and nonprotected BALB/cJ mice, the ADP-locus has been mapped to chromosome 2 [linkage group V], approximately 23 centimorgans toward te centromere from the locus controlling agouti coat color. Thus, the protection locus is not linked to either the H-2 region or to previously described loci regulating the replication and disease induction of type-C viruses closely related to the virus associated with the AD775a tumor. The possible functions of the ADP-1 locus are discussed and further aspects of this experimental model are described in the accompanying papers.

Animals↗
PubMed1980

Erythrocyte membrane cation carrier in manic-depressive psychosis.

Erythrocyte Na-K ATPase and sodium pump site numbers were estimated in groups of depressed, manic and recovered patients. The activity of Na-K ATPase per pump site was lower in the depressed group than in the recovered group. In the manic group Na-K ATPase was lower than that of the recovered group, whereas there was no difference in the pump site numbers. In the more severe manics the activity of Na-K ATPase per pump site was significantly lower than that of the recovered patients. Therefore, the change occurring in the erythrocyte membrane cation carrier in manic-depressive psychosis is probably in the activity of individual Na-K ATPase molecules and not in the number of Na-K ATPase molecules per cell.

Binding Sites↗