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G Strassmann

Publications and source records attributed to G Strassmann.

At least 73 records · Page 4Linked to original sources
PubMed1989

Effect of platelet-derived transforming growth factor (TGF) type beta 1 on murine inflammatory mononuclear phagocytes: increased fibronectin production.

The effect of transforming growth factor type beta 1 (TGF-beta 1) on mononuclear phagocytes (macrophages), cells which play an important role in the inflammatory response resulting from tissue wounding, was investigated. We found that fibronectin production by murine inflammatory macrophages is significantly enhanced by highly purified human TGF-beta 1 in a time- and dose-dependent manner. Specifically, 2 pM TGF-beta 1 was sufficient to cause significant elevation of fibronectin levels, which peaked between 24 and 48 hr of incubation. Both TGF-beta 1-induced and basal levels of fibronectin were completely abolished by cycloheximide, suggesting that protein synthesis was required. Furthermore, fibronectin mRNA levels were significantly enhanced in TGF-beta 1-treated macrophages. The inductive capacity of TGF-beta 1 appeared specific since other agents such as phorbol myristate acetate and endotoxin failed to induce fibronectin production. Since macrophages have been recently shown to secrete an inactive form of TGF-beta 1, the ability of this precursor molecule to induce fibronectin production was tested. It was found that partially purified human platelet latent TGF-beta 1 could not induce fibronectin synthesis, whereas acid treatment of the same preparation which releases mature TGF-beta 1 enhanced fibronectin production. Taken together, results presented here suggest that inflammatory macrophages can directly contribute to the formation of extracellular matrix upon interaction with TGF-beta 1 and that these cells lack the ability to augment fibronectin production in response to a platelet-derived latent form of TGF-beta 1.

Animals↗
PubMed1988

Regulation of colony-stimulating factor 1-dependent macrophage precursor proliferation by type beta transforming growth factor.

Transforming growth factor (TGF) type beta, a potent growth modulator, has recently been shown to inhibit the proliferation and function of several types of immune cells. This report investigates the effect of human platelet purified TGF-beta on CSF-1-induced proliferation in liquid cultures. We used two cell types to study TGF-beta effects, bone marrow precursors and a c-myc partially transformed CSF-1-dependent macrophage cell line designated BMM-8. We found that CSF-1-dependent proliferation of both cell types was strongly inhibited by TGF-beta in a dose-dependent manner. Approximately 1.6 and 8 pM TGF-beta inhibited 50% of CSF-1 proliferation of the bone marrow precursors and BMM-8, respectively. Inhibition appeared to be reversible, as bone marrow and BMM-8 cells proliferated in response to CSF-1 after preincubation of the cells in TGF-beta. Interestingly, inhibition of hematopoietic cells was observed only after a lag period of 24 to 48 h after onset of cultures. TGF-beta inhibition was partially diminished when increasing amounts of CSF-1 were added to the cultures. TGF-beta inhibition did not involve secondary inhibitory factors such as IFN or PG, both of which have been previously shown to suppress CSF responsiveness. Finally, flow cytometric analysis of the cell cycle indicated that within 48 h, TGF-beta-treated BMM-8 cells were prevented from entering S phase. These results suggest that TGF-beta may play an important role in the negative regulation of macrophage production.

Animals↗
PubMed1986

Mechanisms of tumor cell capture by activated macrophages: evidence for involvement of lymphocyte function-associated (LFA)-1 antigen.

The lymphocyte function-associated (LFA)-1 molecule is expressed on certain populations of macrophages that have an augmented capacity to capture tumor cells. Accordingly, we analyzed the role of LFA-1 in the establishment of such cell-cell interactions. F(ab')2 fragments of the M17/4, anti-LFA-1 monoclonal antibody (MAb) inhibited the interaction between activated macrophages and tumor cells by up to 80% in a dose-dependent manner. The anti-LFA-1 MAb reduced (between 55 to 79%) the number of P815, LSTRA, or EL-4 tumor cells bound to trypsin-sensitive structures on bacillus Calmette Guerin activated macrophages. The inhibition appeared selective, because a F(ab')2 fragment of anti-Mac-1 did not inhibit such binding. Inhibition of tumor cell capture could be observed as soon as 15 min after the onset of the cell-cell interaction between activated macrophages and tumor cells. Optimal inhibition occurred when both tumor targets and macrophages were precoated with the MAb. Although P815, LSTRA, EL-4, and BW5147 tumor cells all expressed LFA-1, only the first three but not BW5147 cells were bound by activated macrophages. Furthermore, endotoxin-pulsed macrophages elicited by thioglycollate broth expressed the LFA-1 antigen but did not exhibit selective tumor cell capture. Finally, anti-LFA-1 inhibited the development of weak into strong binding. Taken together, the results suggest that LFA-1 molecules can participate in the interaction between activated macrophages and neoplastic cells.

Animals↗
PubMed1986

Biochemical models of interferon-gamma-mediated macrophage activation: independent regulation of lymphocyte function associated antigen (LFA)-1 and I-A antigen on murine peritoneal macrophages.

IFN-gamma can induce the expression of both class II histocompatibility antigens (Ia) and the lymphocyte function associated (LFA)-1 antigen on murine peritoneal macrophages. We have examined the molecular changes which lead to altered expression of these two cell surface proteins to determine whether they are regulated by similar or independent mechanisms. While I-A antigen expression can be induced or enhanced by treatment of macrophages with either phorbol diesters and/or the Ca2+ ionophore A23187, these agents had no effect upon expression of LFA-1 under similar conditions. Macrophages from the A/J strain mouse exhibit a deficiency in their sensitivity to IFN-gamma which is seen in our studies as an inability of IFN-gamma to elevate I-A antigen expression. However, expression of I-A could be modulated in these cells by treatment with either phorbol diesters or A23187. In contrast, IFN-gamma could induce LFA-1 antigen on A/J derived macrophages and this was not affected by either phorbol or A23187. Thus these two antigens, despite coordinate expression in response to IFN-gamma in normal mouse strains, are clearly regulated independently. These results suggest that IFN-gamma generates at least two independent molecular events in macrophages which ultimately modulate the expression of cell surface proteins important to the performance of activated functions.

Animals↗
PubMed1985

Antigens associated with the activation of murine mononuclear phagocytes in vivo: differential expression of lymphocyte function-associated antigen in the several stages of development.

Two well-characterized antigens [Mac-1 and lymphocyte-function-associated antigen (LFA-1)], expressed on a variety of leukocytes, are members of a family of surface proteins associated with multiple recognition functions. To analyze expression of these proteins during macrophage development, we utilized both radioimmunoassay and flow cytometry. As previously reported, Mac-1 is expressed on murine macrophages in all stages of development. We found LFA-1 to be present on murine mononuclear phagocytes but only in certain stages of their development. Specifically, we found LFA-1 was expressed on murine tissue macrophages but only on those activated in vivo by bacillus Calmette Guerin (BCG) or, to a lesser extent, primed by pyran copolymer. Although LFA-1 was absent on inflammatory (responsive) and resident tissue macrophages it was also present on blood-borne monocytes. Activated macrophages also selectively expressed the H-11 and Ly-6 antigens. Thus, these data indicate that LFA-1 is selectively expressed on mononuclear phagocytes of the tissues but only on those in the primed and activated stages of development.

Animals↗
PubMed1985

Inhibition of anti-class I cytotoxicity by anti-class II monoclonal antibodies (MoAb). I. Blocking of bulk non-DR and non-DQ-directed cytotoxic T cells by MoAb against DR, DQ, and DP.

We previously demonstrated that although human cytotoxic T lymphocytes (CTL) generated against a lymphoblastoid cell line (LCL) mutant that had lost DR and DQ (formerly known as MB) expression were directed primarily at class I antigens, the lytic activity of such CTL could be inhibited by monoclonal antibodies (MoAb) against monomorphic determinants on DR molecules. Furthermore, the inhibitory effect was found to occur by binding of the MoAb to the target cell, not the effector cell, because lysis of LCL target cells not expressing DR was not inhibited. In this paper we extend this phenomenon to show (i) that MoAbs directed against DQ and DP class II gene products also inhibit the lysis of LCL target cells by CTLs recognizing class I antigens; and (ii) that not all DR-specific MoAbs blocked target cell lysis by non-DR specific CTLs. In addition, when PBLs were used to stimulate the generation of CTLs in mixed leukocyte culture (MLC), inhibition using anti-class II (DR, DQ, and DP) MoAb occurred only when LCLs but not PHA blasts were used as targets. This might be explained by elevated expression of class II molecules on LCLs compared to PHA blasts.

Antibodies, Monoclonal↗
PubMed1985

Inhibition of anti-class I cytotoxicity by anti-class II monoclonal antibodies (MoAb). II. Blocking of anti-class I CTL clones by anti-DR MoAb.

Monoclonal antibodies directed at monomorphic determinants on A,B,C (w6/32) or DR (L243, S4/24, S8/8) HLA antigens were used to inhibit the cytotoxic activity of class I- or class II-reactive CTL clones. Anti-class I (HLA-Bw62) cytotoxic T lymphocyte CTL clones were inhibited by w6/32, but not by L243, when tested on PHA blasts and LCL as targets. Interestingly, S4/24 and S8/8 demonstrated a differential blocking ability of class I reactive clones; these two monoclonal antibodies could not block Bw62-directed CTL clones when using PHA blasts as targets but strongly inhibited the cytotoxic activity of the same clones on LCLs as targets.

Antibodies, Monoclonal↗
PubMed1985

Analysis of human class II antigens by cloned cytolytic T cell reagents: a study using HLA loss mutant lymphoblastoid cell lines and monoclonal antibodies detecting the HLA-DP product(s).

We have utilized cloned T cell reagents and ionizing radiation-induced mutants of an HLA heterozygous lymphoblastoid cell line (LCL) to investigate the determinants detected by the cell-mediated lympholysis (CML) assay. Cells of an LCL clone, 721.501, an HLA haplotype loss mutant expressing the HLA-A2-Cw1-Bw51-DR1-Dw1-DQw1-DPw2-GLO haplotype were used as sensitizing cells for responder cells in vitro. "Cloned" reagents were generated by single-cell deposition of cells of a bulk reagent primed against 721.501 cells. Those clones were screened for cytolytic activity against HLA loss mutant targets (derived from LCL 721) of four different categories; HLA-A2 loss only, A2-Cw1-Bw51 loss, A2-Cw1-Bw51-DR1-DQw1 loss, and the entire HLA haplotype loss. Of 196 clones tested, 36 were cytolytic, including three anti-A2, five anti-Bw51/Cw1, 12 anti-DR1/DQw1, 13 anti-DP region associated with DPw2, and three of undetermined specificity, based on cytolytic patterns against the HLA loss mutant targets. Of 25 anti-HLA class II lytic clones, 23 (92%) fitted the characteristics of helper cell-independent cytolytic T cells (HITc), whereas only two of eight (25%) anti-class I clones were HITc. The 13 anti-DP region clones were divided into three subgroups defined by blocking by anti-FA and not Tü39 monoclonal antibodies (MoAb), by Tü39 and not anti-FA, and by both MoAbs.

Antibodies, Monoclonal↗
PubMed1985

HLA-DR expression on cytotoxic T lymphocytes.

A DR-null and DQ-null mutant lymphoblastoid cell line (LCL) was used to generate cytotoxic T cells (CTL) to investigate DR expression on CTL. Effector T cells generated in human allogeneic mixed lymphocyte culture (MLC) were separated on a fluorescence-activated cell sorter (FACS) into DR-positive and DR-negative subsets. The great majority of detectable cytolytic activity, anti-class I and anti-class II (presumably anti-DP) CTL, as well as natural killer (NK)-like activity, resided within the DR-positive population.

Antibodies, Monoclonal↗
PubMed1985

Studies on antigens associated with the activation of murine mononuclear phagocytes: kinetics of and requirements for induction of lymphocyte function-associated (LFA)-1 antigen in vitro.

Macrophages activated and primed in vivo, although not resident or responsive macrophages, express the lymphocyte function associated (LFA)-1 antigen. By contrast, the biochemically related Mac-1 antigen is expressed on all populations of macrophages. In the present paper, we studied regulation of the LFA-1 antigen in vitro. LFA-1 could be induced in vitro on thioglycollate (TG)-elicited but not on proteose peptone (PP)-elicited or resident macrophages. Specifically, macrophage-activating factor (MAF), interferon-gamma (IFN-gamma), or picogram amounts of endotoxin (LPS) induced LFA-1 on TG-elicited macrophages following overnight incubation. Interferon, -alpha or -beta, fucoidin, and colony-stimulating factor were not effective. While some levels of LFA-1 could be detected as soon as 10 hr, peak expression was observed after 16 to 32 hr of incubation. The induction could be completely abrogated by cycloheximide, suggesting that protein synthesis was required. These results indicate that the induction of LFA-1 on mononuclear phagocytes is closely regulated and that the requirements for such induction are distinct from but share certain similarities with induction of cytotoxic functions and expression of Ia antigen.

Animals↗
PubMed1984

The phenotype of antigen-specific suppressor T cells generated in human mixed leucocyte culture depends on the nature of the major histocompatibility regions recognized.

Following secondary stimulation of mixed leucocyte culture (MLC) populations with a class I plus II HLA difference, antigen-specific suppressor-effector cells of the OKT8+4- phenotype are generated. On the other hand, stimulation with a class II HLA genetic difference only gave rise to OKT4+ suppressor T cells. These effector cell populations which were maintained as "lines" by the addition of exogenous T cell growth factor (TCGF) and feeder cells, mediated antigen-specific suppression over a 6-8 week period during which they were assayed. The data reported here demonstrate that the phenotype of suppressor cells, generated in allogenic MLC, depends on the nature of the class of HLA antigen recognized as disparities in the suppressor-generating MLC. Moreover, both OKT8+4- and OKT4+ suppressors, obtained following stimulation with class I plus II or class II genetic disparities, respectively, appear to be specific for DR (or related class II product) antigens.

Antibodies, Monoclonal↗
PubMed1983

Depletion of human NK cells with monoclonal antibodies allows the generation of cytotoxic T lymphocytes without NK-like cells in mixed cultures.

In vitro stimulation of human mononuclear cells with x-irradiated autologous lymphoblastoid cell line (LCL) or allogeneic normal cells in mixed leukocyte cultures (MLC) was previously shown to result in the generation of OKT3+ OKT8+ cytotoxic T lymphocytes (CTL) lytic for allogeneic and autologous LCLs and also of natural killer- (NK) like cells that are OKT3- and primarily OKT8- and are lytic for HLA- NK-sensitive K562 cells. The origin of the NK-like cells was not previously known because, although the majority of fresh human NK cells react with monoclonal antibodies OKM1 and B73.1, lymphocytes bearing these markers are not detected several days after the onset of MLC, when NK-like cells are present. In this study, experiments were undertaken to determine whether NK-like cells generated after stimulation with x-irradiated pooled allogeneic normal cells (poolx) or with autologous LCL are derived from cells expressing antigens reactive with monoclonal antibodies OKM1 or B73.1, which react with fresh NK cells. Mononuclear cells, depleted of monocytes, were stained with OKM1 or B73.1 and fluorescein-labeled goat anti-mouse IgG. Lymphocytes depleted of OKM1+ or B73.1+ cells, by fluorescence-activated cell sorting, and lymphocytes that were stained but not sorted were stimulated for 7 days with either poolx or autologous LCL. The generation of NK-like activity was decreased at least 90% after depletion of cells reactive with OKM1 or B73.1, whereas the generation of CTL against autologous and allogeneic LCL was minimally affected. These findings show that NK-like cells generated in MLC are derived from cells that express the phenotype of fresh NK cells (OKM1+ or B73.1+) and that CTL can be generated in cultures in which relatively little NK-like activity is concomitantly detected, by depleting NK cells with monoclonal antibodies before stimulation.

Animals↗
PubMed1982

Helper cell-independent cytotoxic clones in man.

We report here a class of helper cell-independent cytotoxic T cell (HITc) clones in man that can proliferate in response to antigenic stimulation as well as mediate cytotoxicity. HITc appear to be rare among clones derived from primary in vitro allosensitized culture, but constitute the majority of clones derived from cells sensitized to autologous Epstein-Barr virus-transformed lymphoblastoid cell lines. The implications of the derivation and function of HITc clones are discussed.

Cell Line↗
PubMed1982

Cellular analysis of specificity of antibodies and of delayed type hypersensitivity responses toward some structurally related synthetic antigens: boosting is determined by specificity of T cells.

The crossreactivity between the random synthetic polypeptide antigen poly(Tyr,Glu)-poly(DLAla)--poly(Lys) [(T,G)-A--L] and its ordered-sequence analogs (Tyr-Tyr-Glu-Glu)-poly(DLAla)--poly(Lys) [(T-T-G-G)-A--L] and (Tyr-Glu-Tyr-Glu)-poly(DLAla)--poly(Lys) [(T-G-T-G)-A--L] at the level of humoral and cellular responses was studied. For delayed type hypersensitivity responses, (T,G)-A--L-activated T cells could be challenged with the homologous antigen as well as with the ordered analogs. T cells activated by (T-T-G-G)-A--L could be challenged with either the homologous antigen or with (T,G)-A--L but not with (T-G-T-G)-A--L. Similarly, no cross stimulation was observed between (T-G-T-G)-A--L-activated cells and (T-T-G-G)-A--L, whereas (T,G)-A--L could challenge the latter cells to mediate significant responses. Similar but not identical cross reactions were observed when primed spleen cells or lymph nodes were transferred to irradiated recipients that were boosted for the production of antibodies. In contrast to observations at the level of cellular responses, (T-G-T-G)-A--L-primed spleen or lymph node cells could not be boosted with (T,G)-A--L for the production of detectable amounts of antibodies, although boosting with the homologous antigen resulted in significant levels of (T-G-T-G)-A--L-specific antibodies. Transfer experiments in which mixtures of T and B cells, each primed to a different ordered polypeptide antigen, were injected into irradiated recipients showed that successful cooperation occurs provided that the boost is given with the T-cell-specific antigen. The antibodies produced were specific to the antigen used for B-cell priming. The T-cell-B-cell collaboration probably occurs through specific determinants that are shared between the two antigens in which the ordered peptides are attached to the same multichain polymer and that are recognized by both the T and the B cells.

Amino Acid Sequence↗
PubMed1980

Elicitation of delayed-type hypersensitivity responses to poly(L-Tyr,LGlu)-poly(DLAla)--poly(LLys) by anti-idiotypic antibodies.

The in vivo effect of murine anti-idiotypic serum against C3H.SW anti-poly(LTyr,LGlu)-poly(DLAla)-(LLys) [(T,G)-A--L] antibodies on delayed type hypersensitivity responses to (T,G)-A--L was studied. Anti-idiotypic serum could challenge DTH responses in C3H.SW mice transferred with antigen-sensitized T cells. The elicitation activity was shown to be antigen and strain specific. With H-2-compatible (but allotype different) strain combinations of (T,G)-A--L-educated T cells and recipients, we were able to show that the biological effect of the anti-idiotypic serum is expressed on the first antigen-sensitized idiotype-positive radioresistant T cell, but not on the proliferating normal cells of recipient origin that participate in the efferent phase of delayed-type hypersensitivity responses to (T,G)-A--L.

Animals↗
PubMed1980

Genetic regulation of delayed-type hypersensitivity responses to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys). II. Evidence for a T-T-cell collaboration in delayed-type hypersensitivity responses and for a T-cell defect at the efferent phase in nonresponder H-2k mice.

The intercellular interactions and the site of the genetic defect in delayed-type hypersensitivity (DTH) response to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys) [(T,G)-A--L] has been studied in a system where the T-cell education phase was separated from the efferent phase. In the cellular response, T-T-cell collaboration is required, because T cell-depleted mice were unable to manifest DTH responses after they were transferred with educated and irradiated T cells. Reconstitution of adult thymectomized mice that were irradiated and supplemented with bone marrow cells after treatment with anti-Thy-1.2 serum and complement, with T cells but not with accessory cells gave rise to significant responses. Educated, radioresistant cells required the presence of normal radiosensitive T cells for successful DTH responses to (T,G)-A--L. The genetic defect of nonresponder H-2k and H-2a mice has been located in the above-mentioned, second T-cell population that participates in the efferent phase of this immune reaction. Further characterization revealed that the educated cells are of the Lyt1+ phenotype and that the second normal T cells are expressing the Lyt 1+,2+,3+ phenotype. Thus, the genetic defect of H-2k and H-2a mice in the DTH response to (T,G)-A--L is expressed on the non-antigen-stimulated Lyt 1+,2+,3+ T cells.

Animals↗