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Biomedical subjects

D L Greiner

Publications and source records attributed to D L Greiner.

At least 55 records · Page 3Linked to original sources
PubMed1997

Prolonged survival of mouse skin allografts in recipients treated with donor splenocytes and antibody to CD40 ligand.

Combined treatment with antibody against CD40 ligand and one transfusion of donor splenocytes prolonged survival of fully mismatched BALB/c skin allografts on C57BL/6 recipients, with approximately 20% of grafts surviving > 100 days. In vitro alloresponsiveness in treated animals was reduced in the immediate post-transplantation period, but by day 100 was increased despite the presence of a successful allograft. The presence of alloreactivity on day 100 was confirmed in vivo by adoptive transfer, which suggests that our protocol had induced either a state of "split tolerance" or "graft accommodation." Mice with skin grafts that had survived for > or = 100 days revealed no evidence of lymphoid chimerism. Treatment with donor splenocytes and antibody against CD40 ligand permits long-term survival of highly antigenic donor skin allografts despite the presence of functionally intact alloreactive lymphocytes.

Adoptive Transfer↗
PubMed1997

Enhanced human CD4+ T cell engraftment in beta2-microglobulin-deficient NOD-scid mice.

Genetic crosses produced NOD/LtSz mice doubly homozygous for the severe combined immunodeficiency (scid) mutation and the beta2m (B2m) null allele. Both NOD/LtSz-scid/scid and NOD/LtSz-scid/scid B2m(null) mice lacked mature lymphocytes and serum Ig. However, homozygosity for the B2m(null) allele also resulted in the absence of MHC class I expression, loss of NK cell activity, accumulation of iron in the liver, and rapid clearance of human IgG1. NOD/LtSz-scid/scid B2m(null) mice supported markedly elevated levels of human T cell engraftment, compared with NOD/LtSz-scid/scid control animals, following injection with human PBMC. The increased engraftment was associated with a major increase in the number of human CD4+ T cells. Following injection with 20 million human PBMC, levels of human CD4+ T cells in the peripheral blood and spleen of NOD/ LtSz-scid/scid B2m(null) mice were 6- to 7-fold higher than those in NOD/LtSz-scid/scid mice and >50-fold higher than those in C.B-17-scid/scid mice. The resulting normalization of CD4+/CD8+ ratios in NOD/LtSz-scid/scid B2m(null) mice is in sharp contrast to that observed in NOD/LtSz-scid/scid mice or in C.B-17-scid/scid mice. Circulating human IgG was cleared 6-fold more rapidly in NOD/LtSz-scid/scid B2m(null) mice than in NOD/LtSz-scid/scid mice. This rapid IgG clearance suggested a failure of the engrafted human lymphoid cells to maintain high circulating levels of human IgG. The higher levels of human CD4+ T cells and the normalization of the CD4:CD8 ratio that are observed in human PBMC-engrafted NOD/LtSz-scid/scid B2m(null) mice suggest that this system may be an excellent model for studies of HIV pathogenesis.

Animals↗
PubMed1997

Characterization of mouse Rt6.1 NAD:arginine ADP-ribosyltransferase.

Rat RT6 proteins, and perhaps mouse Rt6, identify a set of immunoregulatory T lymphocytes. Rat RT6.1 (RT6.1) and rat RT6.2 (RT6. 2) are NAD glycohydrolases, which catalyze auto-ADP-ribosylation, but not ADP-ribosylation of exogenous proteins. Mouse Rt6.1 (mRt6.1) also catalyzes auto-ADP-ribosylation. The activity of mouse cytotoxic T lymphocytes is reportedly inhibited by ADP-ribosylation of surface proteins, raising the possibility that mRt6 may participate in this process. The reactions catalyzed by mRt6, would, however, need to be more diverse than those of the rat homologues and include the ADP-ribosylation of acceptors other than itself. To test this hypothesis, mRt6.1 and rat RT6.2 were synthesized in Sf9 insect cells and rat mammary adenocarcinoma (NMU) cells. mRt6.1, but not rat RT6.2, catalyzed the ADP-ribosylation of guanidino-containing compounds (e.g. agmatine). Unlike RT6.2, mRt6.1 was a weak NAD glycohydrolase. In the presence of agmatine, however, the ratio of [adenine-14C]ADP-ribosylagmatine formation from [adenine-14C]NAD to [carbonyl-14C]nicotinamide formation from [carbonyl-14C]NAD was approximately 1.0, demonstrating that mRt6.1 is primarily a transferase. ADP-ribosylarginine hydrolase, which preferentially hydrolyzes the alpha-anomer of ADP-ribosylarginine, released [U-14C]arginine from ADP-ribosyl[U-14C]arginine synthesized by mRT6.1, consistent with the conclusion that mRt6.1 catalyzes a stereospecific Sn2-like reaction. Thus, mRt6.1 is an NAD:arginine ADP-ribosyltransferase capable of catalyzing a multiple turnover, stereospecific Sn2-like reaction.

ADP Ribose Transferases↗
PubMed1997

Severe defects in immunity and hematopoiesis caused by SHP-1 protein-tyrosine-phosphatase deficiency.

Spontaneous mouse mutations that cause severe immunodeficiency or autoimmunity are invaluable tools with which to investigate the mammalian immune system. Mutations at the 'motheaten' locus result in severe immunological dysfunction due to disruption of the structural gene encoding Src-homology 2-domain phosphatase-1 (SHP-1). This natural model for a specific protein-tyrosine-phosphatase deficiency is being widely utilized to determine the role of SHP-1 in the negative regulation of multiple signaling pathways in a number of hematopoietic lineages.

Animals↗
PubMed1997

Dietary cow's milk protein does not alter the frequency of diabetes in the BB rat.

One theory of the pathogenesis of IDDM proposes that exposure to cow's milk proteins triggers the disease in genetically susceptible individuals. We tested this hypothesis in the BB/Wor rat model of human IDDM. Diabetes-prone (DP) BB/Wor rats spontaneously develop IDDM. Coisogenic diabetes-resistant (DR) BB/Wor rats do not develop diabetes spontaneously, but IDDM can readily be induced by treatment with polyinosinic:polycytidylic acid and depletion of RT6+ T-cells. Pregnant BB/Wor rats were fed one of four experimental diets or a standard Purina commercial rat chow (5010) that was certified to be free of cow's milk protein. Offspring were maintained on the maternal diet after weaning. DP-BB/Wor rats, fed either of two experimental diets based on hydrolyzed casein and free of intact milk protein (Nutramigen or D11236), developed diabetes at only half the rate of animals fed Purina 5010 chow. Neither the addition of bovine serum albumin (BSA) to Nutramigen nor the substitution of total milk protein for the hydrolyzed casein in the D11236 diet increased the frequency of spontaneous diabetes. In contrast, there was no relationship between diet and susceptibility of DR-BB/Wor rats to IDDM induction. However, the methods used to induce IDDM in DR-BB/Wor animals were found to induce antibodies against BSA. We conclude the following: 1) Dietary modification can reduce spontaneous IDDM expression in DP-BB/Wor rats, but the agent of protection is not elimination of cow's milk protein. 2) The addition of BSA or intact milk protein does not abrogate the effectiveness of a protective diet. 3) The genetic susceptibility of the DR-BB/Wor rat to autoimmune diabetes is unaffected by any of the tested diets, but a role of anti-BSA-like autoreactivity in IDDM expression cannot be excluded.

Animals↗
PubMed1997

Effects of HgCl2 on the expression of autoimmune responses and disease in diabetes-prone (DP) BB rats.

Repeated exposure of Brown Norway (BN) rats to relatively low doses of HgCl2 induces autoantibodies to renal antigens (e.g., laminin) and a membranous glomerulonephropathy characterized by proteinuria. In contrast, Lewis (LEW) rats are "resistant" to the autoimmune effects of mercury and, when exposed to this metal, are protected against experimental autoimmune encephalomyelitis (EAE) and Heymann's nephritis. To date, there is no information on "suppressive" effects of mercury in naturally occurring (so-called "spontaneous") rat models of autoimmune disease. Therefore, we have administered HgCl2 to diabetes-prone (DP) BB rats, animals that spontaneously develop both insulin-dependent diabetes mellitus (IDDM) and thyroiditis. We found that DP rats treated with mercury or water for a period of 40-125 days developed autoantibodies to thyroglobulin, with a higher incidence in HgCl2-injected animals (92% vs. 56% in H2O-injected controls). A novel finding of our study was the detection of autoantibodies to laminin in the same rats, again with an increased incidence after HgCl2 treatment (83% vs. 44%). IgG2a was the most frequently detected isotype of antibodies to laminin, followed by IgG1, IgG2b and IgG2c. The IgG isotype profile suggests that treatment with HgCl2 may activate both Th1 and Th2 lymphocytes in BB rats. In spite of these stimulatory effects on autoantibody responses, we found that there was no difference in the incidence of IDDM and thyroiditis between HgCl2-treated and control animals. We conclude that the suppressive effects of mercury previously observed in EAE and Heymann's nephritis of LEW rats do not occur in "spontaneous" autoimmune IDDM and thyroiditis of BB rats. Therefore, immune suppression caused by HgCl2 cannot be considered a common phenomenon, but may be a genetically determined characteristic of LEW rats, possibly related to a specific or unique cytokine profile of this particular rat strain. In contrast, while mercury does not seem to recruit, induce or rescue regulatory T cell function in DP rats, it does stimulate autoantibody responses in these animals.

Adrenal Glands↗
PubMed1996

Role of natural killer cells on engraftment of human lymphoid cells and on metastasis of human T-lymphoblastoid leukemia cells in C57BL/6J-scid mice and in C57BL/6J-scid bg mice.

The severe combined immunodeficiency (scid) mutation was backcrossed onto the C57BL/6J strain background in order to study the role of natural killer (NK) cells in rejection of normal and malignant human lymphohematopoietic cells. C57BL/6J-scid/scid mice showed severe loss of mature T and B cells accompanied by increased percentages of NK1.1+ cells and myeloid cells. Although little or no serum immunoglobulin was detectable prior to 2 months of age, all mice tested had circulating immunoglobulin by 7.5 months of age. C57BL/6J-scid/scid mice had markedly elevated levels of both hemolytic complement activity and NK cell activity compared with C57BL/6J - (+/+) controls. Weekly injections with anti-NK1.1 antibody resulted in elimination of NK cell activity in C57BL/6J-scid/scid mice throughout 8 weeks of treatment. Although human CEM-C7 T lymphoblastoid tumor cells grew slowly in unmanipulated C57BL/6J-scid/scid mice, anti-NK1.1 treatment resulted in increased growth accompanied by metastasis of human lymphoma cells to the brain, liver, and kidney. In contrast to T lymphoblastoid tumor cells, nonmalignant human peripheral blood mononuclear cells engrafted at low levels in anti-NK1.1-treated as well as in unmanipulated C57BL/6-scid/scid mice. Backcrossing of the beige (bgJ) mutation onto the C57BL/6-scid/scid genetic stock caused decreased NK cell activity accompanied by granulocyte defects. C57BL/6-scid/scid bgJ)/bgJ) mice showed metastasis of human CEM-C7 cells to the brain and other organs but supported only low levels of engraftment with human peripheral blood mononuclear cells. These results demonstrate that NK cells, in the absence of an adaptive immune system, function in resistance to metastasis of human lymphomas and suggest that innate immune factors in addition to NK cell function mediate resistance to engraftment of normal human peripheral blood leukocytes.

Animals↗
PubMed1996

Rat RT6.2 and mouse Rt6 locus 1 are NAD+: arginine ADP ribosyltransferases with auto-ADP ribosylation activity.

RT6 is a glycosylphosphatidylinositol-linked protein found on the surface of mature rat T lymphocytes. Cells that express RT6 have an immunoregulatory function and modulate the expression of autoimmune diabetes mellitus in the BioBreeding rat. A homologue of the rat RT6 gene, designated Rt6, has been identified in the mouse, but expression of mouse Rt6 protein has not been documented. Rat RT6 is known to be a nicotinamide adenine dinucleotide (NAD+) glycohydrolase. We now report that rat RT6.2 and recombinant mouse Rt6 locus 1 proteins possess auto-ADP ribosylation activity. In addition, mouse Rt6 but not rat RT6, catalyzes the ADP ribosylation of exogenous acceptors such as histones. The ADP-ribosyl-protein bonds in auto-ADP-ribosylated rat RT6.2, auto-ADP-ribosylated mouse Rt6, and ADP-ribosylhistone synthesized by Rt6 were stable to HgCl2 and HCl, but labile to NH2OH, consistent with ADP ribosylarginine linkages. To determine if these enzymatic activities could affect the function of rat T cells, the effect of substrate availability on lymphocyte proliferation was examined. An inverse correlation was observed between NAD+ concentration in the medium and the ability of rat T cells to respond to anti-CD3, ConA, and PMA plus ionomycin. The data suggest that lymphocyte surface ADP ribosyltransferases could be involved in signaling and immunoregulatory processes.

ADP Ribose Transferases↗
PubMed1996

Sumatriptan use in a large group-model health maintenance organization.

The outcomes of sumatriptan use at a health maintenance organization (HMO) were studied. The study was conducted during one year beginning immediately after sumatriptan was added to the formulary of a large group-model HMO. Subjects were included on the basis of drug-use evaluation criteria, a positive response to the first dose of sumatriptan (administered at the HMO by a nurse), and ability to participate in a telephone survey. Responders to the first dose were eligible to receive up to six doses of sumatriptan for home use. The telephone survey was designed to assess sumatriptan's effects on migraine headache and to capture data on quality of life, perceived problems with sumatriptan, and patient satisfaction. Patients who received sumatriptan between April and September 1993 were interviewed in late September 1993; patients who received sumatriptan between September and April 1994 were interviewed in late April 1994. Of 180 patients surveyed, 160 (89%) had evaluable responses. Migraine headache improved in two thirds of the patients. Sumatriptan was more effective than previously used agents in three fourths. The mean number of migraine headaches per patient per month decreased from 7.4 to 4.2. Quality-of-life indicators, such as time spent with friends, improved in three fourths. Eighty-three percent reported missing fewer days from work. Ninety percent said they would continue to take the drug, despite a 44% incidence of drug-related problems. There were no unexpected problems. A retrospective review showed that utilization of the HMO's resources was reduced with sumatriptan. Placing sumatriptan on an HMO's formulary led to favorable effects on the frequency and severity of migraine headache, patient quality-of-life indicators and productivity, and resource utilization by the organization.

Adolescent↗
PubMed1996

Cytokine gene expression in islets and thyroids of BB rats. IFN-gamma and IL-12p40 mRNA increase with age in both diabetic and insulin-treated nondiabetic BB rats.

Inflammatory cytokines, particularly those produced by Th1 type lymphocytes, are hypothesized to play a major role in the pathogenesis of autoimmune diseases. The present studies investigated this hypothesis in the BB rat. Diabetes-prone (DP) BB rats develop spontaneous hyperglycemia and thyroiditis. Coisogenic diabetes-resistant (DR) BB rats do not develop either disorder spontaneously, but both diseases are induced by depletion of RT6+ T cells. Reverse transcriptase-PCR was used to measure mRNA encoding type 1 and type 2 cytokines. In both DP and RT6-depleted DR rats, IFN-gamma mRNA was present in islets before and during disease onset. IL-2 and IL-4 mRNAs were minimal or undetectable in infiltrated islets but present in activated peripheral T cells. IL-10 mRNA was present at low abundance in infiltrating T cells. These observations suggested a Th1 type inflammatory response, and consistent with this interpretation, we observed that mRNA encoding the p40 chain of IL-12 was also present before and during disease onset. Similar cytokine mRNA profiles were observed in the thyroids of RT6-depleted DR rats and in the islets of DP rats treated with prophylactic parenteral insulin to prevent diabetes. We conclude that IFN-gamma and IL-12 may play a major role in the expression of insulitis and thyroiditis in the BB rat, that Th1 lymphocytes may predominate over Th2 lymphocytes in these inflammatory lesions, and that prevention of diabetes by insulin is not associated with an alteration in the cytokine gene profile of islet infiltrating cells.

Aging↗
PubMed1996

The rat T-cell surface protein RT6 is associated with src family tyrosine kinases and generates an activation signal.

RT6 is a glycosyl-phosphatidylinositol-linked surface molecule present on most mature rat T-cells. RT6+ T-cells can prevent the expression of autoimmune diabetes in the BB rat, but the mechanism is unknown. Because cross-linking of other glycosyl-phosphatidylinositol-linked T-cell proteins is known to activate T-cells, we investigated the signaling properties of RT6. Antibody cross-linking of RT6 enhanced expression of the alpha subunit of the interleukin-2 (IL-2) receptor and potentiated the proliferation of rat T-cells cultured in the presence of phorbol ester plus recombinant IL-2 (rIL-2) and/or rIL-4. RT6 was found to coimmunoprecipitate with five tyrosine phosphorylated proteins including p60fyn and p56lck, members of the src tyrosine kinase family. Pretreatment of T-cells with phorbol ester increased the phosphorylation of proteins that coimmunoprecipitated with RT6, altered the electrophoretic mobility of several of these coimmunoprecipitated phosphoproteins, and increased the amount of p60fyn and p56lck coimmunoprecipitated with RT6. These data indicate that RT6-mediated signaling events may prime T-cells to respond to exogenous cytokines, suggesting a possible mechanism by which surface RT6 may influence T-cell function.

ADP Ribose Transferases↗
PubMed1996

Thymus atrophy and changes in thymocyte subpopulations of BN rats with mercury-induced renal autoimmune disease.

Administration of low doses of mercury induces autoantibodies to laminin and autoimmune glomerulonephropathy in BN, MAXX and DZB rats as well as in (BN x LEW)F1 hybrids. LEW strain rats are resistant to these immunotoxic effects. Susceptible rats also show lymphoid hyperplasia in spleen and lymph nodes and severe thymic atrophy. It is still uncertain whether these mercury-induced changes have any role in the induction of autoimmune responses to laminin. In the present study, we have examined the effects of mercury on the thymus of susceptible and resistant rats. Histological analysis of thymuses from BN rats revealed extensive disorganization within 15 days following mercury treatment, with loss of demarcation between cortex and medulla. Numbers of thymus cells were significantly decreased in both BN and (BN x LEW)F1 hybrid rats injected with HgCl2. There was no apparent increase in apoptotic cells in the thymus of these animals. By flow cytometry we detected a relative and absolute loss of double-positive CD4+ CD8+ thymocytes in BN (but not in LEW rats) within 15 days of mercury treatment. There was a corresponding increase in the relative proportion of single-positive (CD4+ or CD8+) and double-negative CD4- CD8- thymocytes in mercury-treated BN rats. Absolute increases in the number of CD4+ single-positive thymocytes were also observed. In contrast, mercury-treated LEW rats had no changes in thymus architecture or significant decreases in cell numbers. Since the thymus is important in both position and negative selection of developing thymocytes, immunotoxic effects of mercury on its structure and thymocyte subpopulations may have multiple consequences. Alternatively, we suggest the hypothesis that autoimmunity (and in particular autoantibodies to laminin) may be responsible for the changes observed in the thymus.

Animals↗