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J Van Snick

Publications and source records attributed to J Van Snick.

At least 73 records · Page 4Linked to original sources
PubMed1990

Accessory factors involved in murine T cell activation. Distinct roles of interleukin 6, interleukin 1 and tumor necrosis factor.

Interleukin (IL) 6 was compared to other macrophage-derived products for its capacity to support the proliferation of accessory cell-depleted T cells. Monoclonal anti-IL6 antibodies were found to inhibit completely the "accessory activity" of macrophage supernatants, thus demonstrating the central role played by IL6 in T cell activation. IL6 was apparently more critical for initiating than in maintaining T cell proliferation because anti-IL6 antibodies lost all inhibitory activity when added late to the culture. Moreover, IL6 was not the only accessory factor required for optimal T cell proliferation. Using low-density cultures to minimize the number of contaminating accessory cells, we found that significant proliferation of CD4 cells was obtained only in the presence of both IL6 and IL1. In contrast, with CD8 cells substantial proliferation was obtained with IL6 alone. This response could, however, be enhanced by IL1. Tumor necrosis factor (TNF) and granulocyte/macrophage colony-stimulating factor showed no activity in these assays. The concentrations of IL1 and of IL6 required to support optimal proliferation were 10 pg/ml and 1 ng/ml, respectively. Analysis of the mechanisms underlying T cell activation by IL1 and IL6 indicated that both cytokines were required for optimal production of IL2 but that IL6 alone was sufficient to confer IL2 responsiveness. For CD8 cells, this effect was observed with doses of IL6 about 100 times lower than those required for the induction of IL2 secretion (0.001 vs. 0.1 ng/ml). TNF, which was not capable of inducing IL2 secretion, was also found to induce IL2 responsiveness but only at a concentration approximately equal to 1000 times higher than that of IL6. In accordance with these observations, IL6 and to a lesser extent TNF were found to enhance IL2R expression by CD8 cells. Interestingly, this enhancing effect was totally dependent on the presence of IL2.

Animals↗
PubMed1990

Mast cell growth-enhancing activity (MEA) is structurally related and functionally identical to the novel mouse T cell growth factor P40/TCGFIII (interleukin 9).

We have previously shown that certain bone marrow-derived mast cell (BMMC) lines proliferate in response to a mast cell growth-enhancing activity (MEA) that is distinct from interleukin (IL) 3 and IL 4. Here we provide evidence that MEA is identical with the recently cloned mouse T cell growth factor P40. The evidence is as follows: (a) recombinant P40 displayed all the biological activities ascribed to MEA: it supported the growth of MEA-sensitive BMMC lines, it induced IL 6 secretion by these cells, and it enhanced survival of primary mast cell cultures; (b) highly purified MEA stimulated the growth of P40-dependent cell lines; (c) a rabbit monospecific antiserum directed against P40 specifically inhibited the action of MEA on BMMC; (d) specific binding sites for P40 were detected on BMMC and (e) MEA competed with P40 for binding to P40-dependent T cells, indicating that the two molecules interact with the same receptor. These observations further extend the range of biological activities ascribed to P40 and warrant its proposed designation as IL9.

Animals↗
PubMed1990

IL9 maps to mouse chromosome 13 and human chromosome 5.

Mouse and human cDNA clones encoding the T-cell and mast cell growth factor P40, now designated IL-9, were used to identify DNA restriction fragment length polymorphisms (RFLPs) in sets of somatic cell hybrids and between inbred strains of mice and interspecific backcross progeny. Segregation of mouse and human chromosomes among somatic cell hybrids indicated a location on mouse chromosome 13 and human chromosome 5. RFLPs were identified among inbred strains of mice. Analysis of chromosome 13 alleles for Tcrg, Dhfr, and Il-9 in an interspecific cross between Mus musculus and NFS/N or C58/J mice indicates that IL9 is distal to Tcrg and proximal to Dhfr.

Alleles↗
PubMed1990

Cloning and expression of a cDNA for the human homolog of mouse T cell and mast cell growth factor P40.

A cDNA encoding the human homolog of mouse T-cell and mast cell growth factor P40 was derived from peripheral blood mononuclear cells (PBMC) stimulated with phytohemagglutinin and phorbol myristate acetate. Sequence analysis of the cDNA predicted a precursor protein of 144 amino acids including a signal peptide of 18 residues, a structure identical with that of mouse P40. The homology between the mouse and human proteins is 55% with a perfect conservation of the 10 cysteine residues present in the mature polypeptide. Expression of the cDNA for human P40 in a baculovirus vector yielded a protein capable of enhancing in vitro survival of human T cell lines.

Amino Acid Sequence↗
PubMed1989

T cell derived IL-6 is differentially required for antigen-specific antibody secretion by primary and secondary B cells.

IL-6 (formerly PCTGF, HP-1, BSF-2, HGF, IFN-beta 2, 26 kDa) is a recently defined lymphokine demonstrating activity on multiple cell types, including hepatocytes, thymocytes, T cells, plasmacytomas, and B cells. The biologic effects of IL-6 on lymphocytes, particularly B cells, suggest this factor may be involved in the regulation of normal immune responses. Accordingly, we have investigated the role of IL-6 in Ag-specific responses of B cells from both naive and Ag-primed mice. When Ag-primed splenic T cells were used as a source of help, naive (primary) B cell responses specific for the hemagglutinin molecule of the influenza A virus (PR8) were fully inhibited by the addition of an anti-IL-6 antiserum, and are thus IL-6 dependent. In contrast, secondary B cell responses were essentially IL-6 independent, being unaffected by this antiserum even at concentrations 10-fold higher than required to completely inhibit primary responses. This differential IL-6 requirement was further investigated by using a panel of hemagglutinin molecule-specific Th clones. Consistent with the above findings, a Th1 clone secreting biologically active IL-6 enables antibody secretion by both primary and secondary B cells, whereas Th1 clones that do not produce IL-6 support secondary responses, but fail to help primary B cell responses unless exogenous IL-6 is added. These results provide the first instance of differential lymphokine requirements among primary vs secondary B cell responses, and suggest T cell-derived IL-6 plays a critical role during the regulation of humoral immune responses. Moreover, functionally distinct Th1 clones were identified that differed in IL-6 secretion and their corresponding ability to induce Ig secretion by primary and secondary B cells.

Animals↗
PubMed1989

Distinct roles of IL-1 and IL-6 in human T cell activation.

We have examined the mechanisms underlying the activation of human T cells by IL-1 and IL-6. We report that PHA-stimulated accessory cell-depleted tonsillar T cells fractionated on the basis of their density show a high degree of heterogeneity in their proliferative response to these cytokines, inasmuch as small dense lymphocytes essentially fail to respond whereas large cells proliferate extensively. This differential response could be ascribed to the fact that only the large cells produced IL-2 under these circumstances, thus providing unequivocal evidence for the existence of an IL-2-mediated step in the activation of human T cells by IL-1 and IL-6. The synergy between IL-1 and IL-6 was found to result from their complementary effects on the production of and response to IL-2, with IL-1 playing a preponderant role in the induction of IL-2, and IL-6 being required, in addition to IL-1, for optimal IL-2-responsiveness. Using small tonsillar T cells, it was possible to show that, concomitant with the enhanced response to IL-2, IL-6 induced a marked increase in cell size and in protein synthesis. In the absence of other factors, this activation was not followed by entry into S phase, suggesting that the essential role of IL-6 in T cell activation is to induce the cells to move from G0 to G1, where they become more responsive to the small amounts of IL-2 induced by IL-1.

Animals↗
PubMed1989

Accessory signals in murine cytolytic T cell responses. Dual requirement for IL-1 and IL-6.

We have examined the nature of the accessory factors required for the development of primary murine CTL in accessory cell-depleted allogeneic mixed lymphocyte cultures. None of the known macrophage-derived factors was active by itself but the combination of IL-1 and IL-6 induced cytolytic responses equivalent to those of unfractionated cultures. Experiments with purified T cell subsets and antibodies blocking the action of IL-2 and IL-4 demonstrated that IL-1 and IL-6 acted directly on CD8+ cells capable of growth factor production. Analysis of the respective roles of IL-1 and IL-6 indicated that IL-6 acts before IL-1 and is capable apparently by itself to induce responsiveness to IL-2. By contrast, production of IL-2 required the additional presence of IL-1.

Animals↗
PubMed1989

Complete amino acid sequence of a new murine T-cell growth factor P40.

A new murine T-cell growth factor, designated P40, which supports growth of helper T-cells in the absence of interleukin-2, interleukin-4 and antigen has been isolated from helper T-cell lines in sufficient quantities (100 micrograms) to permit its complete amino acid sequence determination. This was achieved by a combination of sensitive peptide mapping using microbore reversed-phase high performance liquid chromatography and automated microsequence analysis. Attempts to obtain N-terminal sequence data on P40 were unsuccessful due to N-terminal blockage of the native molecule. The nature of this N-terminal blocking was established using a combination of amino acid analysis, fast-atom-bombardment mass spectrometry and peptide synthesis. The P40 molecule, a single polypeptide chain comprising 126 amino acid residues, is structurally distinct from other known T-cell growth factors. No similarity was revealed when the amino acid sequence of P40 was compared with other proteins whose biochemical structure is known. The protein sequence data reported here predict four N-linked glycosylation sites in the P40 molecule.

Amino Acid Sequence↗
PubMed1989

Cloning and characterization of a cDNA for a new mouse T cell growth factor (P40).

Recently, we described a murine helper T cell-derived molecule with T cell growth factor activity that is functionally and structurally distinct from IL-2, IL-4, and other known growth factors. This molecule, designated P40, was identified as a glycoprotein capable of supporting antigen-independent growth of certain helper T cell clones. Here, we report the cloning and expression of a cDNA for this new growth factor. The predicted mature protein is a cationic cysteine-rich polypeptide of 14 kD without significant homology to previously sequenced proteins.

Amino Acid Sequence↗
PubMed1989

Inhibition of cryoprecipitation of murine IgG3 anti-dinitrophenyl (DNP) monoclonal antibodies by anionic DNP-amino acid conjugates.

Previously we have demonstrated that eight out of nine IgG3 monoclonal antibodies (mAb) obtained from autoimmune MRL-lpr/lpr mice were able to self-associate and to precipitate in the cold (Gyotoku et al., J. Immunol. 1987. 138:3785). To determine whether the cryoprecipitation of IgG3 mAb is enhanced or inhibited in the presence of specific ligand, we have established eight IgG3 mAb reactive with 2,4-dinitrophenol (DNP) hapten: four mAb were obtained from fusion of spleen cells of C57BL/6 mice immunized with 2,4,6-trinitrophenylated keyhole limpet hemocyanin, three from 129/Sv and one from BALB/c immunized with DNP-lipopolysaccharide. Five of them induced cryoglobulins composed exclusively of the IgG3 mAb. The binding of negatively charged monomeric DNP-amino acid conjugates completely inhibited the cryoprecipitation of all the five cryoprecipitating anti-DNP IgG3 mAb, while the incubation with positively charged or neutral DNP-amino acid conjugates had variable effects: increase, inhibition or no change of the cryoprecipitation. In addition, positively charged DNP-amino acid conjugates were able to induce the cryoprecipitation of one of the non-cryoprecipitating anti-DNP IgG3 mAb. Our data showed that (a) IgG3 mAb derived from non-autoimmune strains of mice, similar to IgG3 mAb derived from an autoimmune MRL-lpr/lpr strain, possessed the unique property to self-associate and were able to form cryoglobulins in most cases; (b) although the Fc-Fc interactions of IgG3 mAb play a decisive role in IgG3 cold solubility, IgG3 cryoprecipitation was markedly influenced after interacting with their specific ligand, depending on the charge of the hapten-amino acid conjugate. This suggested that even minor interferences with the electrostatic equilibrium of the IgG3 by the binding of charged hapten molecules induced dramatic changes in the solubility of the IgG3 mAb at low temperature.

Amino Acids↗
PubMed1989

High- and low-affinity receptors for murine interleukin 6. Distinct distribution on B and T cells.

The distribution of the murine receptor for interleukin (IL) 6 was examined on a variety of cells. Binding sites for IL 6 were found on many cell lines including fibroblasts and bone marrow-derived macrophages. The highest density of binding sites was found on B cell hybridomas and plasmacytomas, irrespective of their IL 6 dependence for growth. Scatchard analysis carried out with these cells identified about 1000 high-affinity sites (Kd = 25 pM) and 10,000 low-affinity sites (Kd = 2.5 nM). The binding was specific for IL 6 and led to the internalization of the ligand. Receptors for IL 6 were also present on other B cell lines, but binding on normal resting or activated B cells was below the limit of detection (less than 3 molecules/cell). In contrast, receptors were found on mature thymocytes and on peripheral T cells. However, unlike plasmacytomas and hybridomas, T cells expressed only high-affinity binding sites. The difference in the relative numbers of high- and low-affinity receptors on different cells suggests that IL 6 interacts with several proteins, the expression of which varies from one cell type to another.

Animals↗
PubMed1989

TCGF III/P40 is produced by naive murine CD4+ T cells but is not a general T cell growth factor.

Several antigen-specific T cell lines were found to secrete a lymphokine upon activation by antigen or lectin that was provisionally termed T cell growth factor III (TCGF III) because it induced the proliferation of a CD4+ T cell clone independently from IL2 and IL4. Amino acid sequence analysis (and the functional properties of TCGF III) revealed that TCGF III was identical with a recently identified lymphokine termed P40. TCGF III/P40 was not only produced by long-term cultured T cell lines but also upon stimulation of freshly isolated Mlsa-reactive T cells. In addition, naive CD4+ T cells secreted TCGF III/P40 upon activation by lectin or allo-major histocompatibility complex structures. However, in spite of its growth-promoting activity for a CD4+ T cell clone this lymphokine does not appear to function as a general growth factor for T cells.

Amino Acid Sequence↗
PubMed1989

Interleukin 3 mediates interleukin 6 production in murine interleukin 3-dependent hemopoietic cells.

A series of murine interleukin 3 (IL-3)-dependent hemopoietic cell lines was studied for the capacity to produce interleukin 6 (IL-6) in vitro. These included a bone marrow-derived mast cell line (L138.8A) and several early myeloid cell lines described in the literature (DA-1, DA-3, NFS-60, NFS-78, FDC-P1, FDC-P2, FDC-PmixA4, and 32Dcl.23). All of these cell lines produced growth factor activity for IL-6-dependent hybridoma cells (7TD1), which was completely neutralized by the monoclonal anti-IL-6-antibody 6B4. IL-6 expression was also evident at the mRNA level using a murine IL-6-specific cDNA probe. In 32Dcl.23 cells (2 x 10(5)/ml) stimulated for 24 hr with serial dilutions of purified murine IL-3, a positive correlation was found between the IL-3 dose and the amount of IL-6 measured in the conditioned media. At 24 hr this correlation was not evident at the mRNA level. However, prolonged exposure of 32Dcl.23 cells (up to 72 hr) to either a high (60 U/ml) or a low IL-3 concentration (1 U/ml) revealed a time-dependent increase and decrease, respectively, of IL-6 mRNA levels. At both IL-3 concentrations 32Dcl.23 cells remained in a fully viable and proliferative state. The influence of IL-3 on IL-6 release could be specifically counteracted by anti-IL-3-antiserum. IL-6 added alone or in concert with IL-3 did not stimulate 32Dcl.23 proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Mouse IL-6. A hybridoma growth factor with multiple effects on normal B and T cells.

The effects of IL-6 on plasmacytomas and on normal B and T cells were examined. Evidence was presented to indicate that, in the mouse, IL-6 not only supports the growth of plasmacytomas in vitro, but also that it significantly enhances tumor progression in vivo. Analysis of the response of normal mouse B cells to IL-6 revealed the existence of a unique synergy between IL-6 and IL-1. The results obtained with T cells also highlighted the remarkable effects of the IL-1-IL-6 combination. In several experimental systems, including the generation of allogeneic cytolytic T cell responses, it appeared that accessory cells could be completely replaced by IL-1 and IL-6, whereas either cytokine used by itself was completely inactive. Analysis of the mode of action of IL-6 in T cell activation demonstrated the existence of two distinct mechanisms: induction of IL-2 biosynthesis and enhancement of T cell responsiveness to IL-2 and IL-4. Finally, it was reported that IL-6 is essential only during the early phases of T cell activation, thus indicating as far as T cells are concerned that IL-6 must be considered as a competence factor.

Animals↗
PubMed1989

Mouse bone marrow-derived IL-3-dependent mast cells and autonomous sublines produce IL-6.

This study deals with the question of whether mouse bone marrow-derived mast cells are able to produce interleukin-6 (IL-6) in vitro. For this purpose, a panel of primary mast cell clones from limiting-dilution microcultures, of permanent IL-3-dependent mast cell lines and autonomous malignant sublines, was screened. All of these lines were found to produce growth factor activity for IL-6-dependent mouse hybridoma cells (7TD1), which could be completely neutralized by the monoclonal anti-IL-6-antibody 6B4. Transcriptional activity of the IL-6 gene was demonstrated in both IL-3-dependent mast cells and autonomous sublines using a mouse IL-6-specific cDNA probe.

Animals↗