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M Röllinghoff

Publications and source records attributed to M Röllinghoff.

At least 145 records · Page 8Linked to original sources
PubMed1988

Studies on the release of cell-associated interleukin 1 by paraformaldehyde-treated murine macrophages.

Experiments are presented demonstrating the release of interleukin 1 (IL1) by lipopolysaccharide-stimulated murine macrophages (M phi) after treatment of the cells with paraformaldehyde (PFA). The IL1 activity set free was completely blocked by a rabbit anti-mouse IL1 alpha antiserum. Immunoprecipitation studies revealed that the IL1 released was of Mr 33 kDa, 23 kDa and 17 kDa. Incubation of PFA-treated M phi in the presence of leupeptin reduced the amount of detectable low molecular mass (i.e. 23 kDa and 17 kDa) IL1 alpha. Addition of leupeptin to PFA-treated M phi also reduced the amount of released IL1 activity, suggesting that proteolytic modification of the IL1 alpha precursor is involved in the generation of biological active IL1 alpha. It is proposed that the cell-associated 33-kDa IL1 is released from the M phi by vesiculation of parts of the M phi cell membrane, followed by a proteolytic cleavage step.

Animals↗
PubMed1988

Plasmids of Yersinia enterocolitica and Yersinia pseudotuberculosis: analysis with restriction endonucleases.

The plasmids of Yersinia enterocolitica and Yersinia pseudotuberculosis tested differed in regard to the following aspect: there were some of a molecular size of 41 to 47 Mdal which could be correlated with autoagglutination of the host bacteria, and the others with a smaller size of 19 to 34 Mdal that lacked the capacity to code for autoagglutination. Analysis of both types of plasmids with the restriction endonucleases Bam HI, Eco RI and Hind III besides of some similarities revealed also considerable serogroup-specific differences in their DNA fragmentation pattern.

DNA Restriction Enzymes↗
PubMed1988

Immunological characterization of Yersinia enterocolitica O:9 and O:3 LPS antigens by monoclonal antibodies.

LPS-specific monoclonal antibodies induced against Y. enterocolitica serotype O:9 bacteria and against Y. enterocolitica O:3 were used in a comparative study to characterize the O:9 and O:3 LPS. Yersinia bacteria grown at 22 degrees C and 37 degrees C and LPS preparations thereof were tested. SDS-PAGE, Western blot analysis and adsorption procedures revealed that LPS of Y. enterocolitica O:9 differed from that of Y. enterocolitica O:3 in: (i) its repeating LPS O-side-chain sugar, (ii) its shorter length of the LPS O-side-chain and (iii) its failure to show temperature-dependent variation in the length of O-side-chains.

Animals↗
PubMed1988

Polyclonal B-cell stimulation by L3T4+ T cells in experimental leishmaniasis.

The well-established polyclonal B-cell stimulation in the lymphoid organs in mice infected with Leishmania major is thought to be dependent on T cells. Here we present clear experimental evidence that this is indeed the case by showing that BALB/c-derived, L3T4-positive L. major-specific T cells induce syngeneic B cells to polyclonal proliferation and immunoglobulin production.

Animals↗
PubMed1987

Murine cutaneous leishmaniasis: comparative study on the capacity of macrophages from "healer" and "non-healer" mouse strains to control L. tropica replication.

A comparison has been made between the capacity of macrophages of BALB/c "non-healer" mice and C57BL/6 "healer" mice to deal in vitro with Leishmania tropica (L. tropica) parasites in order to obtain a more detailed picture of the inherent contribution of macrophages to the susceptibility of BALB/c mice to infection with L. tropica and the resulting fatal course of the disease. In comparison to macrophages of C57BL/6 origin, BALB/c macrophages showed a higher parasite uptake and a higher infection rate; they allowed a more rapid transformation of L. tropica promastigotes into amastigotes and displayed less leishmanicidal activities. Lymphokine-rich culture supernatants induced activation of macrophages resulting in killing of L. tropica by macrophages of both, "non-healer" and "healer" mice. These supernatants also induced expression of Ia-antigens on infected "non-healer" and "healer" macrophages. The results of this study clearly point to the critical role of macrophage functions to either support a systemic leishmaniasis or to alternatively mount a protective immune response leading to a self-healing course of the disease.

Animals↗
PubMed1987

Kinetics of cell-mediated immunity developing during the course of Leishmania major infection in 'healer' and 'non-healer' mice: progressive impairment of response to and generation of interleukin-2.

Leishmania major (L. major)-infected mice of 'non-healer' (BALB/c) and 'healer' (C57BL/6) mouse-strain origin were studied with regard to the kinetics of cell-mediated immunity developing during the course of the disease. Cells obtained from lymph nodes draining L. major-infected footpads were comparatively analysed for their representation in the respective L3T4+, Lyt-2+ and sIg+ lymphocyte subsets; they were studied for their capacity to release interleukin-2 and to proliferate in response to L. major antigen and concanavalin A, including the determination of the frequencies of T cells proliferating antigen-specifically with or without an exogenous source of IL-2. The data obtained indicate L. major infection-induced long-lasting alterations in the cellular composition of the lymph node in both 'healer' and 'non-healer' mice. Moreover, they suggest that the inability of 'non-healer' mice to recover from L. major infection is associated with a progressive impairment of their lymph node T cells to release interleukin-2 in the culture supernatant and to respond to this lymphokine in vitro.

Animals↗
PubMed1986

Suppressive effect of cyclosporin A on the development of Leishmania tropica-induced lesions in genetically susceptible BALB/c mice.

The effect of cyclosporin A (CyA) application on the development of cutaneous lesions was analyzed in genetically susceptible BALB/c mice infected s.c. with Leishmania tropica promastigotes. Daily i.p. injections of CyA, beginning 2 days before or at the day of the infection, dose dependently inhibited the development of parasite-induced lesions; no effect on the lesions was observed, however, if CyA application was started 14 days after the infection. Cessation of CyA administration after having successfully suppressed the cutaneous lesions for a period of 42 days, resulted in the development of lesions within 3 days. CyA had no inhibitory effect on lesions developing in L. tropica infected hypothymic BALB/c nu/nu mice. CyA or CyA-containing mouse serum did not directly affect the viability and the growth rate of L. tropica promastigotes, suggesting that the effect of the agent was imposed on the cells participating in the formation of the cutaneous lesions. Quantitative analysis of the cell distribution in the spleens of infected mice revealed that CyA markedly suppressed the infection-associated numerical increase of splenocytes. Within the Thy-1+ lymphocyte compartment, CyA had its most pronounced effect on the Lyt-1+ T lymphocyte subset. Early in the disease, the frequency of splenic cells proliferating in response to L. tropica antigen in vitro was clearly inhibited by CyA; in the later stages of the infection, however, this effect could not be observed, indicating the presence of L. tropica-inducible T cells being relatively resistant to CyA. Taken together, our findings indicate that CyA reversibly inhibits or delays the parasite-induced expansion of Lyt-1+ splenic T lymphocytes, and thus suppresses the biological function of those T cells that are instrumental for the formation of cutaneous lesions in L. tropica-infected BALB/c mice.

Animals↗
PubMed1985

On the partial suppression of IL-2 receptor expression and the prevention of lectin-induced lymphoblast formation by cyclosporine A.

The effect of cyclosporine A (CyA) on the expression of the Tac-antigen (IL-2 receptor) on PHA-activated PBMNC was analysed by immunofluorescence. In the initial experiments we determined the number of Tac(+) cells, disregarding cell size; we found that CyA did not affect the number of cells expressing the Tac antigen after lectin stimulation (Fig. 1, Table 1). When we found that comparable numbers of Tac(+)-lymphocytes absorbed less IL-2 when grown in CyA as compared to solvent controls, we analysed in more detail the correlation between Tac-antigen expression and cell size of cell populations grown in CyA. It was found that CyA prevented a majority of PHA-activated PBMNC to undergo blastogenesis despite having expressed the IL-2 receptor. A minority of the cells, however, were refractory to the CyA-mediated suppression of blast formation. Studies analysing the Tac antigen expression semiquantitatively showed that CyA reduced the intensity of Tac antigen expression on cells of all sizes.

Cyclosporins↗
PubMed1984

Quantitative representation of all T cells committed to develop into cytotoxic effector cells and/or interleukin 2 activity-producing helper cells within murine T lymphocyte subsets.

A limiting dilution culture system based on stimulation with concanavalin A (Con A) has been used to study the quantitative distribution of helper and of cytotoxic precursor cells in Lyt-2-defined subpopulations of murine T cells. Virtually all of the selected Lyt-2+ and Lyt-2-T cells grow and expand to large clonal colonies within an 8-9-day culture period. Our data show that upon stimulation with Con A, 90% of the Lyt-2-T cells were capable to produce interleukin 2 (IL 2) activity. In addition, IL 2 activity is produced by 8-10% of Lyt-2+ T cells. However, at the clonal level, the average of the IL2 activity produced by Lyt-2+ T cells is about 8-fold less as compared to Lyt-2-T cells. Precursors of cytotoxic T cells were almost exclusively found in the Lyt-2+ population, of which about 70% displayed lytic activity in a lectin-dependent cytolysis test. For the vast majority of clones analyzed the capacity to produce IL 2 activity and the capacity to express lytic activity, was found to be mutually exclusive. A minority of clones (less than 3%) was found to simultaneously produce IL 2 activity and to express cytotoxicity. These latter cells are therefore considered as bifunctional T cells.

Animals↗
PubMed1984

Growth, interleukin-2 production, and responsiveness to IL-2 in T4-positive T Lymphocyte populations from malignant cutaneous T cell lymphoma (Sézary's syndrome): the effect of cyclosporin A.

Functional analysis and surface phenotyping using monoclonal antibodies have revealed that malignant T lymphocyte populations in the peripheral blood of patients with Sézary's syndrome resemble the T helper cell populations from normal individuals. In this article we have studied the effects of the immunosuppressive drug cyclosporine A (CsA) on growth, interleukin-2 (IL-2) production, and the induction of IL-2 responsiveness of peripheral blood monocytes (PBMs) from five patients with Sézary's syndrome in vitro, using the lectin phytohemagglutinin (PHA) and the phorbol ester phorbol myristate acetate (PMA) as stimuli. The following results were obtained: PHA-induced cell proliferation was significantly more sensitive to inhibition by CsA than that induced by PMA or a combination of PMA and PHA (P less than .005). Sézary PBMs produced only small amounts of IL-2 in response to PHA. Stimulation with PMA, however, resulted in significant IL-2 production. PMA and PHA, when given in combination, acted synergistically. The low levels of IL-2 production induced by PHA or PMA were more sensitive to CsA-mediated suppression than those induced by a combination of PHA and PMA (75% and 55% suppression, respectively). CsA-mediated growth suppression could be overcome if the cultures were supplemented with appropriate amounts of exogenous IL-2. We conclude from our data, that CsA in Sézary PBMs inhibits T cell growth indirectly as a consequence of suppression of IL-2 growth indirectly as a consequence of suppression of IL-2 production. Moreover, like normal T lymphocytes, Sézary PBMs do not express the IL-2 receptor spontaneously, but can be induced to do so. CsA does not interfere with intracellular events leading to the expression and the biologic function of the IL-2 receptor.

Cyclosporins↗
PubMed1983

Analysis of interleukin 2 receptor sites on activated T cells.

Earlier work has shown that upon polyclonal or antigen-specific activation murine T cells become susceptable to the affect of the T helper cell product Interleukin 2 (IL-2) leading to clonal expansion of activated T cells. It has been suggested that T-cells, as a result of mitogenic or antigenic triggering, express on their surface receptor sites for IL-2. The aim of the present investigation was to analyse the putative IL-2 receptors by quantitative absorption studies. The following results were obtained: activated T cells, triggered by cell antigen or Con A as well as cells of a CTL-clone, but neither LPS-activated B cells nor tumour cells absorbed IL-2; IL-2 was absorbed in a doses dependent fashion until saturation of the absorbing cells; IL-2 absorption occurred within minutes and was temperature-dependent; data comparing activated T cells versus gluteraldehyde-treated activated T cells in repeating absorptions suggested that with gluteraldehyde-treated cells only absorption of IL-2 by the exposed IL-2 receptors is measured, while metabolically active cells seem to assay, besides of the mere binding of IL-2, also an enzymatic event, which probably follows binding of IL-2 to its receptor. The capacity to absorb IL-2 was trypsin-sensitive but insensitive to treatment with neuraminidase.

Animals↗
PubMed1983

Analysis of lymphokine producing T helper cells at the clonal level.

The quantitative representation of alloreactive helper T lymphocytes (HTL) within murine Lyt 1+2- cells has been analysed by the limiting dilution approach. Using three different experimental protocols evidence is presented that the HTL limiting the overall generation of both T help and IL-2 production may be distinct from the actual HTL providing T help or producing IL-2. While the former most likely represents the T inducer cell occurring at a frequency of about 1/2000 within Lyt 1/2- cells, the frequency of the latter is estimated to be about 1/200-1/500.

Animals↗
PubMed1982

T-T cell interactions during in vitro cytotoxic T lymphocyte responses. V. Precursor frequencies and specificity of alloreactive helper T cells.

We assessed the quantitative representation and specificity of alloreactive helper T lymphocytes (HTL) within murine spleen cells by three different limiting dilution systems. For the induction of primary cytolytic T lymphocyte (CTL) responses towards alloantigens, a Lyt-1+23- HTL precursor (HTLp) could be defined, which occurred at frequencies of 1/2.000-1/50,000, depending on the alloantigen in question. The HTLp limiting for interleukin-2 (Il-2) production also expressed the Lyt-1+ phenotype and occurred in similar frequencies. This cell type was concluded to be the limiting HTLp for the overall helper activity required for the induction of primary CTL responses. HTLp reactive to Mlsa -encoded antigens occurred at higher frequencies (1/500) than those reactive towards whole allogeneic H-2 haplotypes (1/4,000-1/7,000). Within the H-2 complex, I region-encoded alloantigens activated approximately 10 times more HTLp than did H-2K or H-2D regions. When alloreactive HTL were tested for antigen specificity at the clonal level, approximately 80% of the HTL clones proved to be specific to the alloantigen used for immunization, whereas approximately 20% reacted also towards third-party alloantigens. The data are discussed with respect to putative T-T interactions within the helper T cell population and the precision of alloantigen recognition by HTL.

Animals↗
PubMed1982

Dissection of the proliferative and differentiative signals controlling murine cytotoxic T lymphocyte responses.

Evidence is presented that interleukin 2 (IL-2) is not sufficient to cause the differentiation of primary cytotoxic T lymphocytes (CTL). Sources of IL-2 were compared for their ability to cause proliferation as well as differentiation into CTL. Whereas all factors caused proliferation, only the crude Con A supernatant had cytotoxic T cell differentiation factor (CTDF) activity. Furthermore, factors absorbed with an IL-2-dependent cell line to remove IL-2 still retained CTDF activity. Thus, IL-2 functions to cause clonal expansion of CTL precursors preactivated by antigen or mitogen, but for their differentiation into CTL, an additional factor is required, here called CTDF.

Animals↗