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R Benner

Publications and source records attributed to R Benner.

At least 145 records · Page 8Linked to original sources
PubMed1984

Suppression of antigraft immunity by preimmunization. II. Characterization of the suppressor cells.

Immunization of mice with irradiated (20 Gy) or non-irradiated allogeneic spleen cells i.v. induces delayed-type hypersensitivity (DTH)-reactive T cells, as well as suppressor T cells, against histocompatibility antigens. The suppressor T cells are unable to suppress the induction and functional activity of the simultaneously activated DTH-reactive T cells. However, the suppressor T cells do suppress the generation of DTH-reactive T cells after subsequent s.c. immunization of the same mice, and after transfer into secondary recipients. Systemic transfer of suppressor T cells is effective the first few days after their induction, and affects the afferent limb of the DTH response. The population of suppressor T cells, which is essential for the systemic transfer of suppression, appeared to be Lyt-1+2+. Splenectomy experiments showed that the spleen is not essential for induction of the suppressor T cells. The precursors of the suppressor T cells belong to the pool of recirculating T lymphocytes; they are insensitive to adult thymectomy and can be depleted by antithymocyte serum treatment.

Animals↗
PubMed1984

Preparation, characterization, and microbial degradation of specifically radiolabeled [C]lignocelluloses from marine and freshwater macrophytes.

Specifically radiolabeled [C-lignin]lignocelluloses were prepared from the aquatic macrophytes Spartina alterniflora, Juncus roemerianus, Rhizophora mangle, and Carex walteriana by using [C]phenylalanine, [C]tyrosine, and [C]cinnamic acid as precursors. Specifically radiolabeled [C-polysaccharide]lignocelluloses were prepared by using [C]glucose as precursor. The rates of microbial degradation varied among [C-lignin]lignocelluloses labeled with different lignin precursors within the same plant species. To determine the causes of these differential rates, [C-lignin]lignocelluloses were thoroughly characterized for the distribution of radioactivity in nonlignin contaminants and within the lignin macromolecule. In herbaceous plants, significant amounts (8 to 24%) of radioactivity from [C]phenylalanine and [C]tyrosine were found associated with protein, although very little (3%) radioactivity from [C]cinnamic acid was associated with protein. Microbial degradation of radiolabeled protein resulted in overestimation of lignin degradation rates in lignocelluloses derived from herbaceous aquatic plants. Other differences in degradation rates among [C-lignin]lignocelluloses from the same plant species were attributable to differences in the amount of label being associated with ester-linked subunits of peripheral lignin. After acid hydrolysis of [C-polysaccharide]lignocelluloses, radioactivity was detected in several sugars, although most of the radioactivity was distributed between glucose and xylose. After 576 h of incubation with salt marsh sediments, 38% of the polysaccharide component and between 6 and 16% of the lignin component (depending on the precursor) of J. roemerianus lignocellulose was mineralized to CO(2); during the same incubation period, 30% of the polysaccharide component and between 12 and 18% of the lignin component of S. alterniflora lignocellulose was mineralized.

Journal Article↗
PubMed1984

Anaerobic biodegradation of the lignin and polysaccharide components of lignocellulose and synthetic lignin by sediment microflora.

Specifically radiolabeled [C-lignin]lignocelluloses and [C-polysaccharide]lignocelluloses were prepared from a variety of marine and freshwater wetland plants including a grass, a sedge, a rush, and a hardwood. These [C]lignocellulose preparations and synthetic [C]lignin were incubated anaerobically with anoxic sediments collected from a salt marsh, a freshwater marsh, and a mangrove swamp. During long-term incubations lasting up to 300 days, the lignin and polysaccharide components of the lignocelluloses were slowly degraded anaerobically to CO(2) and CH(4). Lignocelluloses derived from herbaceous plants were degraded more rapidly than lignocellulose derived from the hardwood. After 294 days, 16.9% of the lignin component and 30.0% of the polysaccharide component of lignocellulose derived from the grass used (Spartina alterniflora) were degraded to gaseous end products. In contrast, after 246 days, only 1.5% of the lignin component and 4.1% of the polysaccharide component of lignocellulose derived from the hardwood used (Rhizophora mangle) were degraded to gaseous end products. Synthetic [C]lignin was degraded anaerobically faster than the lignin component of the hardwood lignocellulose; after 276 days, 3.7% of the synthetic lignin was degraded to gaseous end products. Contrary to previous reports, these results demonstrate that lignin and lignified plant tissues are biodegradable in the absence of oxygen. Although lignocelluloses are recalcitrant to anaerobic biodegradation, rates of degradation measured in aquatic sediments are significant and have important implications for the biospheric cycling of carbon from these abundant biopolymers.

Journal Article↗
PubMed1984

Relative contributions of bacteria and fungi to rates of degradation of lignocellulosic detritus in salt-marsh sediments.

Specifically radiolabeled [C-lignin]lignocellulose and [C-polysaccharide]lignocellulose from the salt-marsh cordgrass Spartina alterniflora were incubated with an intact salt-marsh sediment microbial assemblage, with a mixed (size-fractionated) bacterial assemblage, and with each of three marine fungi, Buergenerula spartinae, Phaeosphaeria typharum, and Leptosphaeria obiones, isolated from decaying S. alterniflora. The bacterial assemblage alone mineralized the lignin and polysaccharide components of S. alterniflora lignocellulose at approximately the same rate as did intact salt-marsh sediment inocula. The polysaccharide component was mineralized twice as fast as the lignin component; after 23 days of incubation, ca. 10% of the lignin component and 20% of the polysaccharide component of S. alterniflora lignocellulose were mineralized. Relative to the total sediment and bacterial inocula, the three species of fungi mediated only very slow mineralization of the lignin and polysaccharide components of S. alterniflora lignocellulose. Experiments with uniformly C-labeled S. alterniflora material indicated that the three fungi and the bacterial assemblage were capable of degrading the non-lignocellulosic fraction of S. alterniflora material, but only the bacterial assemblage significantly degraded the lignocellulosic fraction. Our results suggest that bacteria are the predominant degraders of lignocellulosic detritus in salt-marsh sediments.

Journal Article↗
PubMed1984

Influence of 2'-deoxyguanosine upon the development of DTH effector T cells and suppressor T cells in vivo.

Subcutaneous (s.c.) immunization of mice with allogeneic spleen cells can induce delayed-type hypersensitivity (DTH) to both major and minor histocompatibility antigens. Intravenous immunization with allogeneic spleen cells, however, induces a poor state of DTH. Furthermore, i.v. immunization with allogeneic spleen cells, especially if they have been irradiated, induces suppressor T lymphocytes. These suppressor T cells are capable of suppressing the host-vs-graft (HvG) DTH reactivity that normally arises after s.c. immunization. Moreover, they can suppress the development of anti-host DTH effector T cells during graft-vs-host (GvH) reactions. These models for HvG and GvH DTH reactivity were used to study the influence of 2'-deoxyguanosine (dGuo) and guanosine (Guo) on the generation of DTH-reactive T cells and suppressor T cells in vivo. It was found that daily i.p. administration of 0.01 mg dGuo to mice immunized i.v. partially prevented the generation of suppressor T cell activity, whereas daily administration of 0.1 or 1 mg dGuo resulted in a complete abolition. Administration of dGuo has no effect on the anti-host DTH reactivity by spleen cells from nonsuppressed donors except for when a daily dose of 10 mg is administered. This dose proved to be toxic for precursors of DTH effector T cells. Daily i.p. injection of Guo had no effect on the generation of suppressor T cells nor on the generation of DTH effector T cells. The effect of dGuo was found to be due to a direct effect on suppressor T cells and not to the induction of contrasuppressor cells. These data suggest a differential sensitivity of DTH-reactive T cells and suppressor T cells for dGuo. Because suppressor T cells and DTH-reactive T cells require proliferation for expressing maximal functional activity in the systems used, both cell types probably have different enzyme activities involved in the purine metabolism and similar deoxycytidine kinase activities, but have different nucleotidase (5'NT) activities, those in suppressor T cells being the lowest. If so, suppressor T cells will accumulate deoxyguanosine triphosphate, which causes an inhibition of the ribonucleotide reductase activity and thus of the DNA synthesis by these cells.

Animals↗
PubMed1984

Frequencies of background cytoplasmic Ig-containing cells in various lymphoid organs of athymic and euthymic mice as a function of age and immune status.

The distribution of background Ig-secreting cells, measured as cells containing cytoplasmic immunoglobulin (C-Ig cells), over spleen, bone marrow, lymph nodes and Peyer's patches was studied in congenitally athymic (nude) mice and heterozygous euthymic mice as a function of age and immune status (germ-free (GF) vs specific pathogen-free (SPF]. In young athymic as well as in young euthymic mice, the spleen was found to contain the great part of all C-Ig cells, irrespective of whether the mice were GF or SPF. The number of C-Ig cells in the spleen was found to be rather constant over the life span, while the number of C-Ig cells in the bone marrow of all groups of mice greatly increased with age. This indicates that the relative shift of C-Ig cells to the bone marrow is neither dependent on the presence of the thymus, nor on the microbiological status of the mice. However, at young and intermediate age the microbiological status of the mice did affect the total number of C-Ig cells per mouse. This was mainly due to the effect upon the bone marrow, mesenteric lymph nodes and Peyer's patches. At these ages the background Ig synthesis in these organs appeared to be mainly dependent on external antigenic stimulation, in contrast to the spleen, where the Ig synthesis appeared to be mainly due to endogenous stimulation. The Ig (sub)class distribution of the C-Ig cells was different for all different organs tested. Hardly or no difference in percentage distribution was found between the GF nude and GF heterozygous mice. Most C-Ig cells in spleen, bone marrow and lymph nodes of the GF mice were of the IgM isotype. C-IgG and C-IgA cells occurred in substantial percentages only in bone marrow and lymph nodes. In the lymph nodes of GF nude mice a remarkably high percentage of C-IgA cells was found.

Aging↗
PubMed1984

T-lymphocyte subpopulations in patients with various courses after hepatitis B virus infection.

The course of a hepatitis B virus infection is probably determined by the cellular immune response of the host, which is partly regulated by the T helper and T suppressor cells. We therefore counted immunoregulatory T-cell subsets in the peripheral blood of 97 patients with various courses of hepatitis B virus infection: 23 of these patients were asymptomatic HBsAg carriers without detectable liver disease, 13 had chronic persistent hepatitis B, 19 had chronic active hepatitis B (11 HBeAg, 8 anti-HBe), 7 had chronic active hepatitis with anti-HBs or anti-HBc, and 35 were healthy controls with anti-HBs after recovery from acute hepatitis B. Peripheral blood mononuclear cells were specifically labelled with monoclonal Leu-1 (T cells), Leu-2a (T suppressor/cytotoxic cells), and Leu-3a (T helper cells) antisera and analyzed by flow cytometry. Leu-3a/Leu-2a ratios for patients with persistent virus infection did not differ from those found for patients who cleared the hepatitis virus antigens. There was, however, evidence that the number of T suppressor cells in the subgroup of patients with ongoing chronic active hepatitis and anti-HBe had decreased. These findings suggest that elimination of hepatitis B virus is unlikely to be related to the relative number of peripheral T-cell subsets. The few patients who develop chronic active hepatitis after partial clearance of the virus probably have an enhanced immunoreactivity compared with those with the commoner courses of this disease.

Antibodies, Monoclonal↗
PubMed1983

Suppression of delayed-type hypersensitivity to third party "bystander" alloantigens by antigen-specific suppressor T cells.

Delayed-type hypersensitivity (DTH) against alloantigens can be induced by sc immunization with allogeneic cells. The induction of DTH can be suppressed by iv preimmunization of the mice with similar allogeneic spleen cells, provided the cells are irradiated before injection. This suppression is mediated by T cells. The suppressor activity can be induced not only by H-2-and non-H-2-coded antigens, but also by H-2 subregion-coded antigens. Suppression induced by K, I, or D subregion-coded antigens is specific for that particular subregion as well as for its haplotype. I-J-coded alloantigens were found to not be necessary for the induction of antigen-specific suppressor T cells. After restimulation of suppressor T cells by the "specific" alloantigens, the DTH to simultaneously administered third-party alloantigens becomes suppressed as well. This nonspecific suppression of DTH to third party "bystander" alloantigens also occurs when the specific and the third-party antigens are presented on separate cells, provided that both cell types are administered together at the same site. The simultaneous presentation of both sets of alloantigens during the induction phase of DTH only is sufficient to prevent the normal development of DTH to the third-party antigens.

Animals↗
PubMed1983

The effect of corticosteroids upon the number and organ distribution of "background" immunoglobulin-secreting cells in mice.

The influence of the synthetic corticosteroid dexamethasone sodium phosphate (DEXA) upon the immunoglobulin (Ig)-secreting cells was studied in not intentionally immunized BALB/c mice. This was done for IgM-, IgG-, and IgA-secreting cells in spleen, mesenteric lymph nodes (MLN), and bone marrow (BM). A single injection of DEXA (16 to 144 mg/kg body wt) markedly reduced the number of Ig-secreting cells in spleen and MLN within 1 day, but hardly affected their number in the BM. The decrease was immediately followed by a recovery and, at the highest doses and especially in MLN, by an overshoot. Two weeks after the initial decrease a second decrease was found. When mice were subjected to daily treatment with DEXA during 1 week, initially a recovery pattern was found in spleen and MLN similar to that found after a single injection of a high dose. In this case, however, the effects were less dose dependent, and the overshoot reaction was followed by a period of subnormal numbers of Ig-secreting cells which lasted at least 1 week. This late effect of DEXA not only occurred in spleen and MLN, but also in the BM. The most prominent effect of daily treatment with DEXA was the long-lasting decrease of the number of IgG-secreting cells starting 1 week after withdrawal of treatment. This decrease was associated with a severely decreased serum IgG level.

Animals↗
PubMed1983

Comparison of the sensitivity of the protein A plaque assay and the immunofluorescence assay for detection of immunoglobulin producing cells.

This paper reports a comparative study on the sensitivity of the protein A plaque assay and the cytoplasmic immunofluorescence assay for detection of immunoglobulin (Ig) producing cells in cell suspensions of murine lymphoid organs. The protein A plaque assay was found to detect as many or several times more Ig producing cells than the immunofluorescence assay, depending on the age and antigenic load of the mice, and upon the Ig class and organ studied.

Aging↗
PubMed1983

Secondary delayed-type hypersensitivity to sheep red blood cells and minor histocompatibility antigens in mice: transfer of memory by recirculating thoracic duct lymphocytes.

Secondary delayed-type hypersensitivity (DTH) in mice to sheep red blood cells (SRBC) and minor histocompatibility (H) antigens is dependent on long-lived memory T cells. In this paper we investigated whether these memory T cells recirculate. It was shown that late phase "immune' thoracic duct lymphocytes (TDL) from mice which were immunized with SRBC or non-H-2-incompatible spleen cells several weeks previously could adoptively transfer secondary DTH to these antigens. Passing the immune TDL through intermediate recipients demonstrated that these SRBC- or minor H-antigen-reactive memory T cells recirculate from blood to lymph. In contrast to mice immunized with minor H antigens, no secondary type DTH reactivity could be demonstrated in mice immunized with H-2-incompatible spleen cells. Also, after adoptive transfer of TDL from mice immunized with H-2-alloantigens, it was impossible to demonstrate an accelerated DTH reactivity.

Animals↗
PubMed1983

Specific and nonspecific T-cell-mediated suppression of antihost immune reactivity in graft-versus-host reaction.

Intravenous immunization of mice with irradiated (2000 rads) allogeneic lymphoid cells induces the generation of suppressor T cells. Such suppressor T cells are capable of suppressing the antihost immune reactivity during acute and delayed graft-versus-host reactions. These suppressor T cells are strictly antigen-specific as far as their activation is concerned, but also suppress the reaction against unrelated antigens presented by the irradiated host.

Animals↗
PubMed1983

Isolation of a bacterium capable of degrading peanut hull lignin.

Thirty-seven bacterial strains capable of degrading peanut hull lignin were isolated by using four types of lignin preparations and hot-water-extracted peanut hulls. One of the isolates, tentatively identified as Arthrobacter sp., was capable of utilizing all four lignin preparations as well as extracted peanut hulls as a sole source of carbon. The bacterium was also capable of degrading specifically labeled [C]lignin-labeled lignocellulose and [C]cellulose-labeled lignocellulose from the cordgrass Spartina alterniflora and could also degrade [C]Kraft lignin from slash pine. After 10 days of incubation with [C]cellulose-labeled lignocellulose or [C]lignin-labeled lignocellulose from S. alterniflora, the bacterium mineralized 6.5% of the polysaccharide component and 2.9% of the lignin component.

Journal Article↗
PubMed1983

Increased incidence of transient homogeneous immunoglobulins in irradiated and reconstituted C57BL/KaLwRij mice treated with 2'-deoxyguanosine.

Prolonged administration of micromolar amounts of 2'-deoxyguanosine (dGuo) to lethally irradiated and reconstituted mice led to an increased incidence of transient homogeneous immunoglobulins (H-Ig) in their sera. Analysis of the heavy and light chain isotype distribution among the H-Ig revealed more of the IgG2b and IgG3 isotypes and less of the IgM isotype and the lambda light chain containing H-Ig in the dGuo-treated group as compared to the control group. The increased incidence of H-Ig was preceded by a decreased suppressor T cell generation and activation in the dGuo treated group. These data indicate that deficient suppressor T cell activity plays an important role in the development of transient H-Ig.

Animals↗
PubMed1983

Frequency analysis of functional immunoglobulin C and V gene expression in murine B cells at various ages.

The frequencies of lipopolysaccharide- (LPS) reactive B cells and their antibody specificity repertoire have been determined in the spleen and bone marrow (BM) of mice at different ages. A limiting dilution culture system was employed that allows the growth and development of every LPS-reactive B cell into a clone an IgM-secreting cells that are capable of switching to other Ig heavy chain isotypes (C gene expression). The secretion of IgM and IgG1 was assessed in the protein A plaque assay, whereas specific IgM antibody-secreting cells (V gene expression) were detected with the use of plaque assays specific for various heterologous erythrocytes and sheep red blood cells (SRBC) coupled with a number of different haptens. The frequencies of LPS-reactive B cells in the spleen and BM of C3H/Tif, C57BL/Ka, BALB/c, and CBA/Rij mice appeared to be similar in 6- to 12- and 100-wk-old animals, as was the switch frequency to IgG1 secretion in three strains tested. Moreover, no age-related changes were observed in the frequencies of antigen-specific B cells within the pool of LPS-reactive B cells in the spleen and BM of C57BL/Ka mice. The frequencies ranged from 1 in 10 to 1 in 20 for NIP4- and NNP2-SRBC, from 1 in 50 to 1 in 100 for TNP30-SRBC, and from 1 in 1000 to 1 in 4000 for SRBC, HRBC, and GRBC. The specificity repertoire of the "spontaneously" occurring ("background") IgM-secreting cells in the spleen and BM, on the other hand, did differ between young and old C57BL/Ka mice. During aging the frequencies of the tested specificities decreased in the spleen but increased in the BM. Our data indicate that in unintentionally immunized mice the clonal selection of B lineage cells by antigen takes place at the level of the mature, antigen-reactive B cell.

Aging↗
PubMed1982

The proliferative activity of antibody forming cells in the mouse bone marrow.

The proliferative activity of antibody-forming cells was studied in the bone marrow of mice immunized with either sheep erythrocytes (SRBC), TNP-LPS or DNP-Ficoll. Peak proliferative activity was found during the first few days of the response. Elimination of the proliferating cells in this period caused a profound and longlasting suppression of the antibody formation in the marrow.

Animals↗
PubMed1982

Nonspecific suppression of anti-graft immunity by antigen-specific T suppressor cells.

The specificity of T suppressor cells induced by intravenous administration of irradiated allogeneic spleen cells was studied in mice by means of a delayed type hypersensitivity (DTH) assay. T suppressor cells induced by either H-2K, H-2I or H-2D incompatible cells were found to be specific for the inducing alloantigen. Such antigen specific T suppressor cells can suppress the response to another H-2 alloantigen, provided it is administered together with the alloantigen that had induced the T suppressor cells. Similarly, T suppressor cells induced by non-H-2 alloantigens can suppress the response to H-2 alloantigens if administered simultaneously.

Animals↗