Modulation of anti-tumour immunity and the effect of bacterial endotoxin on the growth of different syngeneic tumours from small inocula in mice.

Studies were undertaken to determine the influence of E. coli lipopolysaccharide (LPS) on the growth of various doses of two antigenically-distinct syngeneic murine fibrosarcomas designated H1 and H7. The ''weakly'' antigenic H1 tumour injected subcutaneously (s.c.) along the abdominal wall was profoundly susceptible to the growth-potentiating effects of a single intraperitoneal (i.p.) injection of 2 micrograms LPS, administered concurrently. ''Sneaking through'' effects in control mice were observed with doses of 10 and 100 H1 tumour cells. Rejection of medium-sized inocula 25 or 500 H1 tumour cells were abolished by the administration of LPS. In contrast, the ''strongly'' antigenic H7 tumour did not exhibit the ''sneaking through'' phenomenon and its growth was only temporarily affected by LPS. Studies were also performed to determine the effect of LPS on the kinetics of delayed-type hypersensitivity (DTH) induced by mitomycin C-treated (MCT) H1 or H7 tumour cells inoculated s.c. into the footpads of mice. The ''strongly'' antigenic MCT H7 tumour cells induced consecutive waves of footpad swelling of diminishing intensity and corresponded to periods of anti-tumour resistance. The specific phase of MCT H7-induced footpad swelling, maximal at day 6, was delayed in its induction if LPS was administered concurrently with MCT H7 tumour cells. In contrast, the ''weakly'' antigenic MCT H1 tumour cells induced only one specific phase of footpad swelling which was rapidly down-regulated. The induction of immunity by MCT H1 tumour cells was also delayed by the concomitant administration of LPS. Because the ''weakly'' antigenic H1 tumour was unable to sustain consecutive waves of anti-tumour immunity, the delay in the expression of such immunity by LPS allowed the H1 tumour cells to multiply to eventually overwhelm a rapidly down-regulated immune response. In contrast, the incidence of tumours arising from the ''strongly'' antigenic H7 tumour cells was not significantly affected in LPS-treated mice because the tumour cells which escaped the first encounter with delayed anti-tumour immunity, succumbed to subsequent waves of resistance in both normal and LPS-treated mice injected with fewer than 1 X 10(5) H7 tumour cells.     

Suppressive effect of bacterial endotoxin on the expression of cell-mediated anti-Listeria immunity.

Intravenous injection of bacterial endotoxin into mice at any time during ongoing infection with Listeria monocytogenes resulted in a markedly increased multiplication of this organism in the liver and spleen. Experiments designed to investigate the basis of this infection-enhancing effect revealed that endotoxin was also capable of inhibiting the expression of adoptive T-cell-mediated anti-Listeria immunity if given to normal recipient mice up to 48 h before they were infused with protective T-cells. On the other hand, endotoxin had only a marginal effect on the expression of adoptive immunity if given to donor mice before their spleen cells were harvested for adoptive transfer. Taken together, these results indicate that endotoxin probably interferes with the antibacterial function of macrophages rather than with mediator lymphocytes. The additional finding that the infection-enhancing action of endotoxin could be greatly reduced by making mice "tolerant" to endotoxin suggests that the acquisition of tolerance to this effect of endotoxin may be an important adaptive mechanism in acquired resistance to infection with gram-negative bacteria.     

Transfusions of syngeneic blood do not seem to induce suppressive effect on antitumor or transplantation immunity in mice

There was no prolongation of allogeneic heart survival or acceleration of tumor development in mice pretransfused with syngeneic blood. Analogous transfusion of donor-specific (allogeneic) blood, without additional immunosuppression, resulted in prolongation of allogeneic heart survival. These results argue against participation of some immunologically unspecific mechanisms in immunosuppressive effect of blood transfusion on transplantation immunity in this model.     

Effect of syngeneic thymocytes on proliferation of the small intestinal epithelium in mice

Bulletin of Experimental Biology and Medicine -     

Combined effect of levan and cytotoxic agents on the growth of experimental tumours in mice.

The combined effect of the polysaccharide levan (previously shown to exert a host-dependent as well as direct antitumoural activity) and the cytotoxic agents cyclophosphamide (CY), methotrexate (MTX), vincristine (VINC) and 5-fluoro-uracil (SFU) was studied in Lewis lung carcinoma and AKR lymphoma. Combined chemo- and immunotherapy was applied beginning on the day of tumour cell inoculation. Additive effects were obtained with the combined treatments, compared to single treatments, with all the combinations except MTX-levan in Lewis lung carcinoma, where the combined effect was synergistic. The additive effect was obtained with different doses and routes of chemotherapy, whether local or intraperitoneal. A 2 mg dose of CY combined with levan administered at daily doses of 10 mg, resulted in a 100% prevention of Lewis lung carcinoma growth. It is suggested that the levan may have two beneficial effects: it can exert an inhibitory effect on tumour growth and diminish the deleterious effect of cytotoxic agents on the immune system.     

Modulation of endotoxin lethality in mice by hydrazine sulfate.

Although the precise mechanism of endotoxin lethality has yet to be defined, it is well recognized that the amount of hepatic phosphoenolpyruvate carboxykinase is reproducibly and significantly reduced after challenge with endotoxin. Hydrazine has been shown to be a specific inhibitor of gluconeogenesis, causing a metabolic crossover at the step catalyzed by phosphoenolpyruvate carboxykinase. More recently, it has also been shown that hydrazine sulfate may be of potential therapeutic value against cancer cachexia. The experiments described in this paper demonstrate that treatment of CF1 mice with hydrazine sulfate 5 h prior to challenge with endotoxin from Salmonella enteritidis significantly improved survival. Furthermore, such treatment counteracted the drop in hepatic phosphoenolpyruvate carboxykinase activity in isolated cytosol otherwise evident at 6 h and 12 h after endotoxin challenge. Despite this, there was no corresponding improvement in the plasma glucose, measured at 6, 12, and 24 h following endotoxin challenge. It is suggested that the endogenous response to the metabolic crossover initiated by hydrazine may contribute to the protection. The response to hydrazine sulfate has yet to be fully elaborated but does include the increase in phosphoenolpyruvate carboxykinase activity. In contrast with the protection seen upon hydrazine sulfate pretreatment, injecting a corresponding dose of hydrazine sulfate after the endotoxin resulted in more fatalities.     

Effect of bacterial endotoxin on gastric evacuation and passive absorption of salicylate in the small intestine

Bulletin of Experimental Biology and Medicine -     

Genetic control of immunity to Trichinella spiralis in mice: capacity of cells from slow responder mice to transfer immunity in syngeneic and F1 hybrid recipients.

Mice of the C57BL/10 (B10) strain are slow responders to infection with T. spiralis in terms of ability to expel worms from the intestine. Compared with rapid-responder NIH mice, infection stimulates a slower and reduced blast cell response in the draining mesenteric lymph node (MLN). Transfer of immune cells from the MLN (MLNC) does not accelerate worm expulsion from naive B10 recipient mice, even though MLNC from this strain effectively transfer immunity to (B10 X NIH) F1 recipients. In common with other B10 background mice C57BL/10 show an infection-dose related suppression of immunity to T. spiralis. Such suppression does not appear to determine the response to MLNC, as adoptive transfer into B10 recipients was not enhanced by reducing the level of challenge infection given, and transfer into F1 recipients was unaffected by simultaneous transfer of lymphocyte populations from donors infected at a level which would induce suppression. A hypothesis is proposed which relates slow response status to (i) the inherent capacity of the intestinal inflammatory component of worm expulsion, and (ii) the outcome of infection-dose related stimulatory and suppressive influences acting on the two interacting lymphocyte components of expulsion. The relevance of H-2-linked and non-H-2 genes to the control of the response is discussed.     

Cell-mediated immune responses to syngeneic ultraviolet-induced tumours. V. Assessment of accessory and antigen-presenting cell capabilities of normal and ultraviolet-irradiated mice in the generation of anti-tumour cytotoxic effector cells in vitro.

Draining lymph nodes (DLN) from tumour immunized mice were found to contain a population of radiation resistant, Thy 1-, Ia+ antigen-presenting cells (APC) which can stimulate normal lymphocytes to differentiate into anti-tumour CTL in vitro. APC from both normal and ultraviolet (u.v.)-irradiated tumour immunized animals were compared and exhibited equivalent functional capabilities. DLN from tumour immunized u.v.-irradiated animals were also found to contain primed T cells which could differentiate into functional anti-tumour cytotoxic T lymphocytes (CTL) with the same kinetic profile as DLN cells from normal tumour immunized mice. These results indicate that u.v. irradiation does not cause a generalized depression in either the capability of APC in u.v.-irradiated mice to process and present tumour antigens, or in the ability of u.v.-exposed animals to be primed to tumour antigens. A decrease in splenic accessory cell function was detected in animals which had received 1 week of daily 30 min u.v. exposures. The decrease in splenic accessory cell function appears to be transient, however, as no decrease in this capability was found in splenic cells obtained from animals which had received daily u.v. exposures for longer periods of time (5 weeks to 5 months). Finally, the spleens of u.v.-irradiated, tumour-bearing mice were found to contain a population of cells which could impart partial protection against tumour growth in vivo. The results of the experiments presented here indicate that normal and u.v.-irradiated animals are capable of responding similarly in the afferent phases of immune responses to syngeneic tumour antigens, and suggest that u.v.-induced T-suppressor cells mediate their immunoregulatory effects at a stage late in the generation of effective anti-tumour immune responses.     

Specific cytostatic effect of lymph node cells from normal and T cell-deficient mice on syngeneic tumor target cells in vitro and its specific abrogation by body fluids from syngeneic tumor-bearing mice

Lymphoid cells from tumor-bearing animals were shown to be cytostatic for syngeneic tumor target cells in vitro using a post labeling radioactive assay. The specific decrease or removal of this cytostatic activity was possible using a “blocking” serum or ascitic fluid from syngeneic tumor-bearing animals. Further lymphoid cells from chronically irradiated, thymectomized mice, which were shown to be extensively deprived of T cells by reduced PHA responsiveness and anti-θ cytotoxicity tests, were also found to cause cytostasis of target tumor cells and to a greater extent than with nondeprived lymphoid cells.     

Protective effect of cinnamicaldehyde in endotoxin poisoning mice

Context: Several pharmacological studies have shown that cinnamicaldehyde (CA) has anti-inflammatory and anti-tumor effects, but no data show the effects of CA on the endotoxin poisoning.

Objective: In this work, the protective effect of CA in LPS-induced endotoxin poisoning mice was investigated.

Materials and methods: Mice were randomly divided into normal, LPS, LPS +5?mg/kg dexamethasone (DEX), LPS +0.132?g/kg CA, and LPS +0.264?g/kg CA group. Pretreated with CA (0.132 and 0.264?g/kg/day, respectively) for 5 consecutive days before LPS injection. Except the normal group, the other animals were intraperitoneally injected with LPS (15?mg/kg).

Results: Twelve hours after LPS injection, CA significantly reduced the production of pro-inflammatory cytokines (interleukin-18, interleukin-1β, and interleukin-5) and chemokines (macrophage colony stimulating factor, macrophage inflammatory protein-1β) in serum. In addition, the histopathological study indicated that CA attenuates lung injury induced by LPS. Moreover, the numbers of neutrophils were significant decreased and the NF-κB (p65) mRNA level was reduced in lung after treated with CA.

Conclusion: The present data suggest that cinnamicaldehyde can be considered as potential therapeutic candidates for the endotoxin-poisoning-related diseases such as sepsis via its anti-inflammation effects.     

Enhancement of T-cell-mediated anti-tumour immunity via the ectopically expressed glucocorticoid-induced tumour necrosis factor receptor-related receptor ligand (GITRL) on tumours

Glucocorticoid-induced tumour necrosis factor receptor-related receptor (GITR) costimulates functions of both effector and regulatory T cells. The administration of agonistic anti-GITR monoclonal antibodies efficiently enhances various T-cell-mediated immune responses; however, it is unknown to what extent the ligand of GITR (GITRL) contributes to T-cell responses. We investigated the involvement of endogenously expressed GITRL on dendritic cells and ectopically expressed GITRL on tumours in T-cell-mediated immunity. Expression of GITRL on dendritic cells in secondary lymphoid organs was limited, and treatment with anti-GITRL monoclonal antibodies did not substantially affect T-cell-mediated immunity to alloantigens, a specific protein antigen (ovalbumin), or tumour antigens. The introduction of GITRL promoted anti-tumour immunity in four tumour models. Tumour-associated GITRL greatly augmented the effector function of CD8⁺ T cells and enhanced the contribution of CD8⁺ T cells. These events reduced the crucial contribution of CD25⁺ CD4⁺ regulatory T cells, which were found to inhibit immunity against tumours lacking GITRL. Peritumoral injection of GITRL tumour vaccine efficiently inhibited the growth of established tumours. Our results suggest that the ectopic expression of GITRL in tumour cells enhances anti-tumour immunity at peripheral tumour sites. Consequently, the combined use of a GITRL tumour vaccine with methods aimed at enhancing the activation of host antigen-presenting cells in secondary lymphoid tissues may be a promising strategy for tumour immunotherapy.     

The effects of endotoxin pretreatment on subsequent challenge of mice with cycloheximide and a small dose of endotoxin

Mice treated with 15.0 micrograms of S. enteritidis endotoxin are completely protected against the coagulopathic effects, but only partially protected against the fatal glucocorticoid deficiency which follow an otherwise lethal challenge with cycloheximide and 5.0 micrograms of the same endotoxin given 3 days later. Hydrocortisone treatment results in survival of all such tolerant, challenged animals. The protection conferred against occlusion of glomerular capillaries by fibrin coagula is abolished by EACA, suggesting that tolerance has induced high levels of fibrinolytic activity by the time of challenge, and evidence indicates that this protective degree of fibrinolytic activity persists for more than 24 h after cycloheximide and endotoxin challenge.     

Histological modifications of the lymph nodes in mice bearing syngeneic grafts of tumours induced by methylcholanthrene.

Light and electron microscopical studies demonstrate that regional but also non-regional lymph nodes of C57BL mice grafted by tumours, induced by methylcholanthrene, are able to elicit a complex immunological response of the cellular, as well as of the humoral types. No significant difference was found according to the growth rate and the immunogenicity of the six tumours investigated. The cellular immunization is predominant during the two first weeks. It is mainly characterized by the appearance in the paracortical area of numerous immunoblasts which are in close connexions with'dendritic' macrophages showing multiple long cytoplasmic expansions. During the same period of time, the reticulum cells become hyperplasic in the sinus. From the 15th day to the death of the animals, the cellular immunizaiton progressively regresses while a humoral immunity develops. It shows itself as an hypertrophy of the lymph follicles and an increase in the number of medullary cord plasma cells.