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Cytotoxic T cell responses to a syngeneic tumour: conditions for primary activation in vitro.

Primary cytotoxic responses of DBA/2 lymph node cells to a syngeneic tumour (the mastocytoma P815) have been generated in vitro. The development of these responses is dependent on the addition of a soluble factor (CSCS) which is produced by concanavalin A-activated spleen cells. The response is mediated by T lymphocytes, can be detected at low effector to target cell ratios and is directed against P815 tumour-associated antigens.

Animals↗

Metabolism of macromolecular heparin in mouse neoplastic mast cells.

1. Polysaccharide in a heparin-producing mouse mastocytoma was pulse-labelled in vivo with [35S] sulphate, and after various periods of time was isolated from subcellular fractions. Such fractions were recovered from tissue homogenates by consecutive centrifugations at 1000g for 10min, 20000g for 20min and 100000g for 1h. Initially the 35S-labelled polysaccharide formed occurred principally in the second centrifugal fraction (20000g precipitate), with small amounts in the first (granular) and third (microsomal) fractions. Analysis for glycosyltransferase activity confirmed that glycosaminoglycans were formed chiefly in particles sedimenting at 20000g. Molecules of this newly synthesized polysaccharide were considerably larger than those of commercially available heparin, as judged from gel chromatography. 2. Within the first hour after injection of [35S]sulphate, most of the labelled polysaccharide was redistributed from the second to the first centrifugal fraction. During, and possibly also after, this shift, the macromolecular polysaccharide was degraded, ultimately to the size of commercial heparin. The degradation process appeared complete 6h after injection of [35S]sulphate. 3. Particulate subcellular fractions were incubated with macromolecular [35S]heparin and the products were analysed by gel chromatography. Significant degradation of the substrate occurred only with the second centrifugal fraction. Further characterization of this fraction, by density-gradient centrifugation in iso-osmotic colloidal silica, revealed a single visible band of particles, at approximately the same density at lysosomes. This band contained all the beta-glucuronidase, 35S-labelled endogenous polysacchride and heparin-degrading enzyme present in the second fraction.

Animals↗

[Toxoplasmosis transmission by blood transfusion? (author's transl)].

T-cells of the chicken tumour HPRS-1, mouse mastocytoma cells, Friend virus-transformed erythroleukaemia cells as well as normal human, mouse and chick erythrocytes were tested for their receptivity to toxoplasma infection. The studies indicate that T-cells and mastocytoma cells, which may be counted as part of the white blood cell series, have the highest invasion rate after incubation with toxoplasma. Friend-erythroleukaemia cells were less often affected; mature human, mouse and chick erythrocytes were refractory. The results suggest that cells of the white blood cell series are receptive to toxoplasma infection but that nucleated precursors of the red series may also be so, while mature erythrocytes cannot be infected. The possibility of transmission of toxoplasmosis by blood transfusion can no longer be doubted.

Animals↗

Comparison between macrophage activation and enhancement of nonspecific resistance to tumors by mycobacterial immunoadjuvants.

It has repeatedly been observed that various bacterial preparations could increase the host's resistance to tumors. It has also been shown that after nonspecific activation by BCG (bacillus Calmette-Guérin), peritoneal macrophages could inhibit in vitro the growth of neoplastic target cells. In the present study a fraction extracted from Myobacterium smegmatis and referred to as interphase material was tested in view of measuring its ability to activate macrophages in vitro and in vivo. This preparation was previously shown to protect mice against a syngeneic leukemia and to increase the immune response of the guinea pig. Other water-soluble adjuvants devoid of demonstrable antitumor activity in vivo were also assayed. The results argue in favor of a correlation between adjuvant activity and the capacity of activating macrophages. Moreover, interphase material administered in vivo consistently induced stronger and more persistent stimulations of macrophages than the other preparations assayed.

Adjuvants, Immunologic↗

Development of tumor cell resistance to syngeneic cell-mediated cytotoxicity during growth of ascitic mastocytoma P815Y.

The immune reactivity to tumor cells within a progressively growing tumor mass in the syngeneic host has been analyzed by studying the cell-mediated cytolytic response of DBA/2 mice to the ascitic mastocytoma P815Y. Peritoneal cells from P815Y tumor-bearing hosts were fractionated by velocity sedimentation at unit gravity. Cell-mediated cytotoxicity of fractionated and unfractionated cells was measured by 51Cr-release from tumor target cells. The cell separation procedure revealed significant levels of specific cell-mediated cytotoxicity to P815Y within peritoneal cell populations at 8-16 days after tumor cell inoculation. Tumor cells purified from the peritoneal cell populations of mice injected with 10(3) tumor cells 10 days previously were as susceptible to syngeneic and allogeneic cell-mediated cytotoxicity as P815Y grown in vitro. However, tumor cells obtained from mice 16 days after tumor inoculation were resistant to cytolysis by syngeneic, but not allogeneic, effector cells. In addition, day 16 tumor cells did not inhibit syngeneic cell-mediated cytotoxicity against P815Y grown in vitro. Immunoglobulin was not detected on day 16 tumor cells and no circulating antibody to P815Y was found in the ascitic fluid of day 16 tumor-bearing mice. These results indicate that tumor cells may escape immune attack by loss of expression of cell surface tumor-associated antigens in the absence of circulating antibody against tumor.

Animals↗

Synthesis and activation of mitotic Ca2+-adenosinetriphosphatase during the cell cycle of mouse mastocytoma cells.

The activity of a Ca2+-adenosinetriphosphatase (ATP phosphohydrolase, EC 3.6.1.3) increases during the mitotic phase of synchronized mouse mastocytoma P-815X2 cells. The enzyme is synchronized mouse mastocytoma P-815X2 cells. The enzyme is synthesized mainly during a distinct period of the interphase and is activated at mitosis. It is thought to regulate the formation of the mitotic apparatus by controlling the concentration of Ca2+ ions at the site of formation of the mitotic spindle.

Adenosine Triphosphatases↗

Dimeric immunoglobulin E serves as a unit signal for mast cell degranulation.

Rat immunoglobulin E (IgE) was treated with a crosslinking reagent, dimethyl suberimidate, and fractionated by gel filtration into monomers, dimers, trimers, and higher polymers. The fractions retained substantial ability to bind specifically to mast cells. About one-third of the cell-bound dimers appeared to bind bivalently. The fractions were assayed in vivo by passive cutaneous anaphylaxis in rats, and for histamine or serotonin release in vitro using normal or tumor mouse mast cells. The monomers showed no activity, while the dimers and higher polymers gave excellent and approximately equivalent responses. We conclude that IgE that has been crosslinked to form dimers prior to the addition to mast cells can serve as a unit signal for triggering IgE-mediated exocytosis.

Animals↗

Induction of spectrin in erythroleukemic cells transformed by Friend virus.

The presence and accumulation in murine erythroleukemic cells transformed by Friend virus of the erythrocyte membrane-associated protein spectrin has been investigated. Spectrin was present in the uninduced cells and was induced 10- to 20-fold in dimethyl sulfoxide-treated differentiating cells. The intracellular concentration of spectrin reached a peak on the third day of dimethyl sulfoxide treatment, after which it fell to levels found in mouse erythrocytes. We also found that the small subunit of spectrin was phosphorylated in the cells.

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Target-effector interaction in the natural killer cell system: isolation of target structures.

A sensitive target binding assay has recently been shown to detect natural killer (NK) cells in the mouse. Preincubation of NK cells with detergent-solubilized cell-surface proteins of YAC lymphoma cells prevented subsequent binding to intact YAC targets. The NK target structures (NK-TS) consisted of three molecular species tentatively assigned molecular weights of 130,000, 160,000, and 240,000 based on electrophoretic mobility in sodium dodecyl sulfate/polyacrylamide gels. Moloney cell surface antigen (MCSA), gp71, p30, H-2, and NK-TS were localized in distinct fractions of gels. The NK-TS bound to concanavalin A-Sepharose columns and could be eluted with the specific sugar, suggesting that the target structures may be glycosylated. NK-TS molecules could not be detected in gels of NK-insensitive target cells such as P815, A9HT, YWA, or EL-4. The quantity obtained from the gels varied directly with the NK sensitivity of YAC which is more sensitive when grown in vitro than when grown in vivo. The NK-TS molecules specifically inhibited the binding of NK cells but not alloimmune T cells to their appropriate targets. Additional NK-sensitive tumor cells also expressed some or all of the target molecules exhibited by YAC. Some of these structures shared specificities in the case of MPC-11 or were unique in the case of Molt-4 and K562, as shown by cross-inhibition studies. These results suggest that NK-sensitive cell lines express distinct target structures with possible relevance to natural tumor resistance.

Animals↗

Immunosuppression by a mouse tumor resembles antigenic competition.

The intraperitoneal injection of gamma-radiated, UV-radiated, or unradiated P-815 tumor cells into syngeneic or allogeneic mice suppressed the immune response to a subsequent intraperitoneal injection of sheep erythrocytes in a manner similar to the suppression caused by the injection of manner similar to the suppression caused by the injection of horse erythrocytes and termed antigenic competition. In both cases, the greatest suppression occurred when the sheep erythrocytes were injected at the same site (intraperitoneal) as the tumor or antigen several days after the tumor or antigen and in a dose of 10(8) erythrocytes or less.

Animals↗

Leukotriene C: a slow-reacting substance from murine mastocytoma cells.

Murine mastocytoma cells treated with calcium ionophore A23187 produced a slow-reacting substance (SRS) that caused guinea pig ileum to contract. The response was reversed by the SRS antagonist FPL 55712. On the basis of isotope incorporation experiments, spectroscopy, and chemical degradations, the SRS was identified as a cysteine-containing derivative of 5-hydroxy-7,9,11,14-icosatetraenoic acid. This amino acid was attached in thioether linkage at C-6. The SRS is structurally related to previously identified epoxy and dihydroxy metabolites of arachidonic acid in leukocytes. A common feature is the presence of a conjugated triene, and the name "leukotriene" has been introduced to designate these compounds. Leukotriene A (5,6-epoxy-7,9,11,14-icosatetraenoic acid) is an intermediate in the formation of leukotriene B (5,12-dihydroxy-6,8,10,14-icosatetraenoic acid) and is proposed to be a precursor also of leukotriene C, which is the SRS identified here.

Animals↗

Proteoglycans of soluble fraction of mouse mastocytoma.

Proteoglycans have been isolated from a high speed supernatant fraction of a mouse mastocytoma by procedures which should minimize alteration of the native protein-polysaccharide molecule. The methods used include in vivo labeling proteoglycans with 35S-sulfate, 3H-leucine and 3H-lysine, centrifugation of the tumor homogenate at 105,000 g, cetylpyridinium fractionation of the supernatant, and further purification of some of the fractions obtained by DEAE-cellulose column chromatography, gel filtration on Sepharose 4B and cellulose acetate electrophoresis. Two major sulfated proteoglycans were obtained, one containing keratan sulfate-like material (KSP-S), the other a heparin-like polymer (HP-S). The presence in HP-S of a compound similar to heparin was confirmed by its digestibility with flavobacterium heparinase. HP-S contained about 4 per cent protein. Glycine was the predominant amino acid, and serine did not appear to be involved in the peptide-carbohydrate linkage. The proteoglycan present in HP-S appeared to be homogeneous when examined using cellulose acetate electrophoresis. KSP-S was found to contain sialic acid and its protein content was significantly higher than that of HP-S. Glutamic and aspartic acids were the most abundant amino acids in KSP-S.

Amino Acids↗

Isolation and characterization of glycosaminoglycans from the Furth murine mastocytoma.

New methods for isolation and fractionation by partition are described and compared with existing techniques. Substantially purer products were isolated by partition as compared to precipitation with hexadecylpyridinium chloride. The glycosaminoglycans isolated fron Furth murine mastocytoma tumor were found to consist of 78-80% heparin, 12-13% chondroitin sulfate, and 8-9% hyaluronate. Dermatan sulfate was not detected. Two heparin-like glycosaminoglycans could be isolated by partition fractionation in the phase system 1-butanol/aqueous NaCl containing hexadecylpyridinium chloride. The composition of one was typical of heparins. However, the other glycosaminoglycan contained only 0.47 moles N-sulfate/mole uronate, but had electrophoretic and partition properties characteristic of heparin.

Animals↗

Correlation between movement of concanavalin A membrane receptors and cytolysis. A scanning electron microscopy study.

The present study was undertaken to test whether cytolysis induced by Concanavalin A (Con A) requires lateral mobility of membranal lectin receptor sites into caps. Treatment of interphase murine mastocytoma cells with 10(-4) M colchicine promoted cap formation by Con A in about 30% of the cells, followed by cytolysis. Pretreatment of the cells with NaN3, low temperature, or glutaraldehyde decreased the degree of capping and, to the same extent, the degree of cytolysis. The addition of antibodies to cells bound with Con A increased the appearance of capping and cytolysis. A linear relationship with a high correlation coefficient exists between the degree of capping and cytolysis, suggesting that lateral mobility of membrane Con A receptors is required for cytolysis by the lectin. The process of cap formation by Con A up to the stage of cytolysis was followed by scanning electron microscopy.

Animals↗

Association of immunity and tolerance to host H-2 determinants in irradiated F1 hybrid mice reconstituted with bone marrow cells from one parental strain.

Semiallogenetic radiation chimeras were prepared by injecting heavily irradiated F1 hybrid mice with bone marrow cells from one parental strain; the bone marrow cells were treated with anti-theta serum and complement to remove T cells and injected in large numbers (2 times 10-7 cells). The mice survived in excellent health until sacrifice 6 mo later. Thoracic duct cannulation at this stage showed that the mice possessed normal numbers of recirculating lymphocytes. Close to 100% of thoracic duct lymphocytes and lymph node cells were shown to be of donor strain origin. The capacity of lymphocytes from the chimeras to respond to host-type determinants was tested in mixed leukocyte culture and in an assay for cell-mediated lympholysis (CML). Mixed leukocyte reactions (MLR) were measured both in vitro and in vivo; tumor cells and phytohemmaglutinin-stimulated blast cells were used as target cells for measuring CML. While responding normally to third party determinants, cells from the chimeras gave a definite, though reduced MLR when exposed to host-type determinants. However, this proliferative response to host-type determinants, unlike that to third party determinants, was not associated with differentiation into cytotoxic lymphocytes. No evidence could be found that unresponsiveness in this situation was due to blocking serum factors or suppressor T cells. It is argued that the results support the concept that lymphocytes responsive in mixed leukocyte culture have a different specificity to those exerting cell-mediated lympholysis.

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Inhibition of T-lymphocyte-mediated tumor-specific lysis by alloantisera directed against the H-2 serological specificities of the tumor.

After appropriate in vivo or in vitro immunization, cytotoxic T lymphocytes (CTL) are generated which efficiently kill cells bearing particular membrane antigens in common with the immunizing cell (reviewed in reference 1). Such CTL have been most thoroughly studied in mice, employing alloimmunization with cells differing at the major histocompatibility locus, H-2. in such cases, the predominant cell surface antigens recognized by the CTL appear to be the molecules carrying the serologically defined H-2 specificities, coded for by the K and D regions of the H-2 complex (2). In other syngeneic models of cell-mediated specific cytolysis, involving lymphocyte chariomeningitis (LCM) virus- or ectromelia virus-infected cells or TNP-modified lymphoid cells, thymus-derived cells also constitute the main effector cell type. The CTL generated in these latter systems function most efficiently when virus-infected or TNP-modified target cells share identitites at the H-2K or H-2D loci with the effector CTL and stimulator cells (3-5). Another set of experimental systems in which CTL are generated and play a significant biological role is that of immunity to tumor-associated antigens (TAA) (6). The nature of the TAA which the CTL recognize is only beginning to be understood. Several recent reports indicated the existence of physiochemical and/or antigenic relationships between TAA and H-2 antigens (7,8). These relationships, together with the genetic restrictions cited above in the generation of CTL involving products of the H-2K or H-2D loci suggested the possibility that in certain tumor systems, the TAA which are able to most effectively stimulate CTL responses might be structurally similar to, or linked with, the H-2K or H- 2D molecules on the tumor surface. It has been previously demonstrated in allogenic models that antisera specific for the appropriate H-2K or H-2D products present on a target cell could specifically block CTL-mediated lysis (1,9). This report demonstrates that certain anti-H-2 alloantisera specific for the target tumor cells can block lysis of those target cells mediated by syngeneic tumor-specific CTL effector cells.

Animals↗

Effect of bacille Calmette-Guérin on the immune response of BALB/c mice to a tumor allograft.

The effect of dosage and route of inoculation of bacille Calmette-Guérin (BCG) on immune response to allogeneic tumor cells was investigated. BALB/c mice were tested 14 and 21 days after injection of EL-4 lymphoma for spleen-cell cytotoxicity against EL-4 cells in vitro and for complement-dependent, antibody-mediated lysis of tumor cells. BCG treatment had no measurable effect on the antibody-mediated lysis of tumor cells, but spleen-cell cytotoxicity was significantly increased in mice treated with 10(4) or 10(8) BCG by the intraperitoneal route; no such increase occurred when BCG was given by the oral or subcutaneous routes. The cytotoxic effector cells were primarily thymus-derived, since treatment of spleens with rabbit antiserum to mouse brain serum decreased cytotoxicity titers by approximately 90%. Within the framework of these experiments, the intraperitoneal route of BCG inoculation resulted in a more effective immune stimulation than the oral or subcutaneous routes.

Animals↗