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Biomedical subjects

R W Dutton

Publications and source records attributed to R W Dutton.

At least 55 records · Page 3Linked to original sources
PubMed1986

Partial purification and characterization of a factor from a cloned thymic epithelium cell line.

The culture supernatant from a cloned line of thymic epithelium (TEPI) is shown to enhance the response of thymocytes to alloantigen as measured by cell-mediated lympholysis. The supernatant has no effect on the spleen cell response to alloantigen as measured by cell-mediated lysis and does not contain interleukin 1, interleukin 2, interleukin 3, or interferon-gamma activity. The activity is shown to have an apparent m.w. of 160,000 by Sephacryl S-200 gel permeation chromatography, to have an isoelectric point of 6.5, and to elute from DEAE-Sepharose at 0.07 M NaCl.

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PubMed1984

Evidence for two distinct activation states available to B lymphocytes.

The sites and modes of action of several B cell mitogens and interleukins were examined. Cell cycle analyses of B cell responses to several polyclonal activators including LPS, DXS, LPS plus DXS, and anti-immunoglobulin were performed. Two different states of B cell activation distinguished by RNA content, DNA content, and cell size were observed. LPS promoted transitions throughout the cell cycle, whereas DXS primarily caused exit from G0. Synergy between LPS and DXS was observed in elicitation of exit from G0. Activation by anti-immunoglobulin was found to be influenced by the antibody dose and the cell density of culture. Interleukins could influence anti-IgM-induced responses by increasing G0 exit, and by increasing commitment to DNA synthesis. A model of B cell activation in which cells are stimulated to a stage with intermediate RNA levels (G1A) by polyclonal activators is suggested. Some interleukins appear to be involved in this process. At G1A, cells are receptive to signals delivered by interleukins or some polyclonal activators that drive them to late G1 and DNA synthesis. After cell division, cells re-enter G1A in which interleukins or mitogens are necessary for a continued response.

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PubMed1984

Partial purification and characterization of a BCGFII from EL4 culture supernatants.

Two B cell growth factor activities have been previously described. One activity, present in the culture supernatants of PMA-induced EL4 is active in a co-stimulator assay with normal B cells and anti-immunoglobulin. The other activity is present in the culture supernatants of the alloreactive T cell line C.C3.11.75 and can be assayed in a co-stimulator assay with normal B cells and dextran sulfate or with BCL1 in vivo line B cell tumor. We have termed the first activity BCGFI and the second BCGFII. We have now shown that a very similar BCGFII activity can be obtained from EL4 culture supernatants induced by PMA. This (EL4)BCGFII has an apparent m.w. of 55,000, is eluted from DEAE Sephacel at 0.05 M NaCl, and has a pI of 5.5, which is clearly distinct from the properties of (EL4)BCGFI activity. (EL4)BCGFII activity is similar to but not identical to (DL)BCGFII. It differs from (DL)BCGFII in chromatographic behavior and in the kinetics of the response of BCL1 to the two factors. (EL4)BCGFII activity can be detected in 18 to 24 hr by virtue of its ability to cause in vitro proliferation of in vivo BCL1 tumor B cells.

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PubMed1983

Evidence for two distinct classes of murine B cell growth factors with activities in different functional assays.

Several previously described B cell growth factor (BCGF) activities from a number of mouse monoclonal T cell sources were compared in different functional assays. The results indicate that there are two distinct classes of BCGF defined by functional activity and source. BCGF I, whose prototype is (EL4)BCGF, synergized with anti-Ig in the proliferation of normal splenic B cells but had no activity when dextran sulfate (DXS), rather than anti-Ig, was used to costimulate the same source of B cells. BCGF I also failed to directly stimulate BCL1 tumor B cells. In contrast, BCGF II, whose prototype is (DL)BCGF, showed a reciprocal pattern of activity. BCGF II failed to synergize with anti-Ig-costimulated normal B cells to give good proliferative responses. Sources of BCGF II also directly stimulated (no anti-Ig or DXS added) B cells of the BCL1 tumor-carrying mice. These results suggest that the two BCGF may have activity on two subsets of B cells that respond differentially to induction with the two polyclonal B cell activators, anti-Ig and DXS. The possibilities that these different patterns of response occur in separate lineages of B cells and/or in B cells in different states of differentiation is discussed.

Animals↗
PubMed1983

Xenogeneic human anti-mouse T cell responses are due to the activity of the same functional T cell subsets responsible for allospecific and major histocompatibility complex-restricted responses.

Human T cells respond strongly to mouse major histocompatibility complex (MHC) antigens. The response is directed predominantly to the polymorphic determinants of the MHC antigens and there is little or no response to the nonpolymorphic determinants or to non-MHC antigens. Human cytotoxic T lymphocytes (CTL) are generated specific for the mouse class I MHC antigens and the CTL effectors are blocked by anti-Leu-2a antisera. Human interleukin 2-producing T cells are generated specific for mouse class II antigens and their induction is blocked by anti-Leu-3a antisera. These and other considerations lead us to propose a model for the T cell receptor that provides an explanation for several of the features of T cell recognition. In this model, the recognition of the "class" (I or II) of MHC antigen is separate from the recognition of the polymorphic determinants. We suggest that the initial recognition of the conserved "class" determinants positions another domain of the receptor so that it can only engage with the part of the MHC molecule carrying the polymorphic determinants.

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PubMed1983

Fetal calf serum-injected F1 mice spontaneously generate specific anti-parental cytotoxic T lymphocytes in in vitro culture.

Spleen cells from adult (BALB/c x AKR/J)F1 mice primed in vivo with fetal calf serum (FCS) can spontaneously generate anti-parental AKR/J cytotoxic T cells (CTL) in a 5-day in vitro culture containing 5% FCS. This response is distinguished by the following features: (i) it is anti-parental but not anti-self, and (ii) it has specificity for the Kk parental determinant as shown by mapping studies on a variety of targets and antiserum-blocking experiments. Although specifically elicited by FCS and mediated by FCS-induced T-helper cells, it is ascertained that this cytotoxicity is not directed against Kk components modified by absorbed FCS as shown by cold-target competition studies. Further experiments involved a comparative investigation of the patterns of lysis of allogenically induced CTL, FCS-induced CTL, and natural killer (NK) cytotoxic activities on tumor cell targets. The resistance of BW 5147 tumor targets to NK- and FCS-induced lysis was found to be dramatically overcome by treatment with mitomycin C, and provides circumstantial evidence for a functional relationship between the FCS-induced anti-parental CTL effectors and NK cells based on the observed similarity in lytic patterns of these two effector types. With reference to the work of other authors, the possibility that hybrid resistance and its possible in vitro counterpart, F1 anti-parental CTL cytotoxicity, and NK activity are mediated by similar or common effector mechanisms is discussed.

Animals↗
PubMed1983

Presence of host-reactive T cells in lymphohaematopoietic chimeras.

The presence of autoreactive lymphocytes was investigated in murine lymphohaematopoietic chimeras. In this report we demonstrate the presence of precursors of host-reactive cytotoxic effector T lymphocytes in parent leads to F1 chimeras. Lymphocytes from these chimeras display cytotoxic activity towards the non-shared major histocompatibility complex (MHC) antigens of the host following activation with the polyclonal T-cell activator concanavalin A. These host-reactive cells were found despite the apparent absence of lymphocytes demonstrating autoreactivity in other experimental systems: mixed lymphocyte reaction, cell-mediated lympholysis, positive allogeneic effect and negative allogeneic effect. Animals possessing precursors of these cytotoxic effector cells also possess precursors of cytotoxic effector cells capable of generating an MHC-restricted anti-minor histocompatibility antigen response. The results are discussed in reference to the role of the thymus in effecting self non-self discrimination.

Animals↗
PubMed1982

Production of a B cell growth-promoting activity, (DL)BCGF, from a cloned T cell line and its assay on the BCL1 B cell tumor.

Culture supernatants from a long-term alloreactive T cell line, the Dennert line C.C3.11.75 (DL) contain a B cell-growth-promoting activity. This activity can be assayed on normal B cells or on the in vivo BCL1 tumor line. We have called this activity (DL)BCGF. This activity can be distinguished from the T cell-replacing factor activity we had earlier found in DL supernates [(DL)TRF], which is required together with IL2 for the B cell plaque-forming cell response to erythrocyte antigens. The (DL)BCGF can be absorbed on untreated or glutaraldehyde-fixed BCL1. This absorption does not remove (DL)TRF activity. The production of (DL)BCGF is greatly enhanced when DL is cultured with IL2-containing supernatants. Sublines or clones of DL (DL.B10 and DL.A4) have been obtained that make large amounts of (DL)BCGF in the absence of any stimulator cells or IL2. B cells from the Xid-deficient male (DBA/2 X CBA/N)F1 mice do not respond to (DL)BCGF.

Animals↗
PubMed1982

A monoclonal T cell-replacing activity can act directly on B cells to enhance clonal expansion.

We have used a B cell cloning system in which the response of a single isolated B cell to lipopolysaccharide and dextran sulfide can be followed. We have shown that culture supernatants from the Dennert long-term alloreactive T cell line C.C3.11.75 increase the frequency of B cells stimulated to clonal expansion by mitogens. These culture supernatants are devoid of interleukin 1 and 2 but contain the T cell-replacing factor activity (DL)TRF. These experiments provide unequivocal proof that a T cell-derived factor or factors can act directly on a B lymphocyte in the absence of any other cell.

Animals↗
PubMed1982

Immunosuppressive ATS. V. Analysis of the effect of anti-thymocyte serum on T lymphocyte subsets.

The effect of anti-thymocyte serum (ATS) on functional T cell subsets within the immunoregulatory network was examined. We found that low doses of ATS depleted the IL 2-producing subset of T helper cells and higher doses of antiserum also eliminated cytotoxic precursors. It was estimated that a standard low dose of ATS, which reduced T helper cells 80-fold, depleted cytotoxic precursors only about four-fold. The data indicate that ATS acts on different T cell subsets in a dose-dependent fashion and suggest that monoclonal antibodies might be used to preferentially deplete specific T cell subpopulations. Two monoclonal rat anti-mouse Lyt sera, however, proved ineffective in inducing functional changes in vivo, although an alloantiserum to Lyt1.1 was able to reduce cell-mediated cytotoxicity in a dose-dependent fashion. The results support the feasibility of specific depletion of T cell subsets with anti-lymphoid antibodies.

Animals↗
PubMed1981

Fine specificity mapping of two allospecific T cell lines: recognition of private specificities in the H-2 IA subregion.

Two allospecific T-cell lines, C.C3.11.75 (H-2d anti-H-2k) and B6.C.7.76 (H-2b anti-H-2d) established from mixed lymphocyte cultures, were selected by continuous antigenic stimulation over several years. Both cell lines proliferated to alloantigen, provided allohelp to B cells in the humoral antibody response, and one of them showed cytolytic activity. Using spleen cells from various congenic mouse strains, the specificity of antigen recognition was examined in order to examine whether there is a correlation between T cell function and antigen recognition. Results showed that in all functional assays. This shows that there is no obligatory correlation between T cell function and antigen recognition and may suggest that the T cell receptor repertoire is biased towards recognizing private specificities.

Animals↗
PubMed1981

The Lyt phenotype of a long-term allospecific T cell line. Both helper and killer activities to IA are mediated by Ly-1 cells.

The relationship between surface antigen expression and function in the long-term allospecific T cell line C.C3.11.75 was examined by flow microfluorometry, antiserum plus complement depletion and cell sorting. T cells of the line expressed Lyt-1, but little or no Lyt-2 antigens. Proliferation to cells bearing Iak determinants, generation of T cell-replacing nonspecific helper factor in response to Iak-positive cells and the killing of Iak-positive targets were dependent only on Ly-1 cells. No obvious heterogeneity was found in this cell line despite its disparate functional activities. The fact that Lyt-2 molecules need not be present for killing directed against Ia determinants indicates that such molecules are not obligatory for the induction or delivery of killing and raises the question of what the role of Lyt molecules in T cell recognition or function might be.

Animals↗
PubMed1981

Culture supernatants of a stimulated T-cell line have helper activity that acts synergistically with interleukin 2 in the response of B cells to antigen.

Culture supernatants of an antigen-stimulated long-term alloreactive T cell line, C.C3.11.75, contain a T-cell-replacing factor (TRF) activity for the B-cell response to antigen. These same supernatants show little activity in the T-cell growth assay or the costimulator assay. TRF activity was assayed by using spleen cells that were rigorously depleted of both T cells and macrophages. In this assay preparations containing interleukin 2 and supernatants from stimulated C.C3.11.75 cells are relatively inactive if added alone but show marked synergy when added together. We conclude that the C.C3.11.75 TRF activity is not due to interleukin 1 or to interleukin 2 but to a third factor provisionally designated as (DL)TRF. This activity may be equivalent to the (late-acting) TRF described by Schimpl and Wecker. Evidence is presented suggesting that the helper activity (DL)TRF is a product of the T-cell line.

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