Immune recognition of tumor cells in mice infected with Pichinde virus

Pichinde virus (PV), a member of the Arenaviridae family, protects mice from a lethal inoculation with the sarcoma 180 (S180) tumor cell line. Virus replication, which is required for protection, occurs primarily in the spleen and tumor. During the first 4 days, elevated natural killer (NK) cell activity parallels an increase in serum interferon in PV-infected mice. On day 7 after infection virus-specific cytotoxic T cells (CTLs) are found in the mouse. This strong response peaks on day 13 and gradually declines over the next 17 days. The tumor-specific CTL response appears more slowly and is less intense than the virus-specific response, especially in the uninfected mouse. However, CTLs from either type of mouse recognize PV-infected tissue culture S180 target cells better than uninfected ones. Even though the primary tumor-specific immune response appears weak, mice that have cleared both virus and tumor are refractory to a subsequent challenge with S180 cells and rapidly produce tumor-specific CTLs. Thus, our data indicate a number of ways in which virus infection could lead to immune elimination of tumors: (1) Virus-induced interferon stimulates NK-cell activity, which in turn could control tumor load until a specific response is mounted against the S180 cells; (2) early onset of the tumor-specific T-cell response could be brought about by viral-enhanced tumor antigen presentation to the immune system; and (3) the tumor-specific T-cell response could be augmented through a "bystander' phenomenon involving factors associated with T cells responding specifically and vigorously to the virus itself.

Coordinated therapeutic effects of immune modulators and interferon

Immune modulators injected 24 h before encephalomyocarditis virus significantly increase antiviral resistance in mice when interferon is administered 1 h after the virus. These immune modulators can be crude bacterial extracts or synthetic drugs. In some cases, the responses are additive; in others, they are clearly cooperative. To protect the mice against the development of 180 TG Crocker sarcomas, the association of bacterial extracts and interferon is highly effective under the condition that the drug concentrations and chronological order and number of injections are well defined. In contrast, the conjunction of interferon and synthetic immune modulators, in particular cimetidine, result in delayed tumor development with no significant change in the final survival rate in the experimental model described here.

Immunoactive peptides, FK-156 and FK-565. II. Restoration of host resistance to microbial infection in immunosuppressed mice

The immunoactive peptides, FK-156 and its analogue, FK-565 were evaluated in various models of mice immunosuppressed with cyclophosphamide, hydrocortisone, mitomycin C, carrageenan and tumor cells. Treatment with FK-156 (subcutaneous) and FK-565 (oral) markedly restored host defense ability against microbial infection. The therapeutic effect of ticarcillin or gentamicin alone against pseudomonal infection in cyclophosphamide- and hydrocortisone-treated mice and tumor-bearing mice was much lower than in normal mice. The therapeutic effect of these antibiotics against pseudomonal infection in immunosuppressed mice was enhanced markedly by combined use with FK-156. The killing ability of macrophages and polymorphonuclear leukocytes of the immunosuppressed mice was also markedly enhanced by dosing with FK-156.

Evolution of sarcoma 180 in mice infected with Trypanosoma cruzi

Mice infected with Trypanosoma cruzi were challenged with 2x10[raised to the power of 6] cells of sarcoma 180 (ascite tumor) by i.p. route, on day seven post infection. Tumor development was followed by evaluation of weight gain, by measurement of ascitic fluid produced and enumeration of tumor cells in ascitic fluid. Infected mice were more resitant to tumor development as demonstrated by reduction in ascites formation and by reduction in the number of tumor cells in ascitic fluid, at different time intervals after tumor challenge. The number of peritoneal cells exsudated after tumor inoculation was greater in infected mice than in controls. This increased resitance of mice infected with T. cruzi to tumor development could be due to the action of macrophages activated by the infection and by the action of endotoxins absorbed from the gut or produced by the own parasite.

Augmentation of host's immunity by combined cryodestruction of sarcoma 180 and administration of protein-bound polysaccharide, EA6, isolated from Flammulina velutipes (Curt. ex Fr.) Sing. in ICR mice

Augmentation of the host's immunity by combined in situ freeze-destruction of the tumor (cryosurgery) and administration of the antitumor active protein-bound polysaccharide, EA6, isolated from a hot water extract of an edible mushroom, Flammulina velutipes (Curt. ex Fr.) Sing., was investigated in sarcoma 180 bearing ICR mice. Oral administration (p.o.) of the EA6 stimulated anti-sheep red blood cells (SRBC) IgM antibody-producing activity of the spleen cells, and also delayed hypersensitivity (DTH) against SRBC in swelling of the foot pads of the tumor-bearing hosts. When EA6 p.o. was combined with cryosurgery, further augmentation of IgM-producing activity and DTH reaction to SRBC was recognized as compared with the EA6 single use. But the reticuloendothelial system of the mice, estimated by carbon clearance test, was not activated by EA6 p.o. or combined with cryosurgery.

Intensification of host's immunity by squalene in sarcoma 180 bearing ICR mice

Effect of highly purified squalene (HP-SQ) obtained from liver of a shark, Centrophorus atromarginative Garman, on antitumor activity and host's immune response was studied in sarcoma 180 bearing female ICR mice. HP-SQ was administered intraperitoneally (i.p.) to solid tumor-bearing or healthy mice at the dose of 0.1 ml/mouse/d for consecutive 10 d. The administration of HP-SQ exerted the host's resistance against challenging 5 x 10(4) cells of ascites sarcoma 180, and it resulted in marked prolongation of survival of the mice (ILS; 110%). Function of the reticuloendothelial system estimated by a carbon clearance test was enhanced by i.p. administration of HP-SQ in both the healthy and the tumor-bearing mice. Number of IgM antibody forming cells against sheep red blood cells (SRBC) in the spleen was counted 4 d after intravenous injection of 2 x 10(7) cells of SRBC. The number of the IgM antibody forming cell increased by HP-SQ administration in the tumor-bearing and the healthy mice. Delayed hypersensitivity reaction against SRBC measuring swelling of the foot pads of mice was also stimulated by the i.p. administration of the material.

Apparent lack of immunogenicity of estrogen-induced testicular Leydig cell tumors in BALB/c mice

Evaluating four in vivo indicators of immune response, we attempted to demonstrate immunogenic properties in transplantable malignant Leydig cell tumors (LCT) induced in BALB/c mice by chronic estrogen administration. Growing LCT failed to elicit the production either of the lymphokine migration inhibition factor by host splenocytes or of circulating antibodies detectable by indirect immunofluorescence. Delayed type hypersensitivity was evaluated in animals "sensitized" by growing tumor explants. Three to 6 weeks after complete tumor excision, 10(6) viable cells or frozen whole-cell equivalents were injected s.c. in one foot pad, and 2 days later the increase in popliteal node weight on that side was determined. Node hypertrophy of "immunized" animals in numerous experiments using many animals was no greater than that in the naive controls, and no evidence could be obtained to suggest the stimulation of T-suppressor cell activity during tumor growth. Finally, pretransplantation treatment of recipients with 400 rads total-body X-irradiation failed to increase the growth rate of four different tumor lines. Thus, although both estrogen-dependent and -independent transfer lines derived from eight different primary tumors were studied, each by several methodologies, we were unable to obtain evidence to suggest that estrogen-induced LCT in BALB/c mice evoke an immunological response while growing progressively in syngeneic hosts. These findings, plus the absence of recognizable virions in the five tumor lines studied by electron microscopy, argue against the participation of an "expressed" virus in the genesis of LCT. The apparent lack of immunogenicity is also consistent with the indefinite persistence of microscopic foci of viable, though dormant, malignant cells in estrogen-dependent LCT that have undergone complete "clinical" regression following hormone withdrawal.

[Experimental studies on antitumor effects of lysozyme-II. Effect of lysozyme on immunopotentiation]

Effects of lysozyme (LY) on immuno-responses were examined. Tumor-bearing mice were used on most of experiments and normal mice on several cases of experiments. Cytostatic activity on the Peyer's patch cells in Meth-A bearing Balb/c mice was enhanced at 6 to 12 hrs after oral administration of LY. Furthermore, LY showed to recover from the decline of blastogenic activity, which was observed on the lymph node cells and the spleen cells of tumor-bearing mice, at 8 and 14 days after tumor inoculation. In the normal ICR mice, it was not observed that LY increased the foot-pad reaction against the sheep red blood cells (SRBC). On the other hand, the decrease of the foot-pad reaction, which was observed in the tumor bearing mice at 20 days after Sarcoma-180 (S-180) inoculation, was recovered by the administration of LY. A decrease of the number of plaque-forming cells (PFC) against SRBC which was induced with tumor inoculation in the spleen cells was not observed at 20 days after S-180 inoculation, but LY caused a significant increase of PFC response in spleens on both of normal and tumor bearing mice. From these results, it was suggested that potentiation of systemic immuno-response derived from the activation of Peyer's patches brought about antitumor effects of LY.

Antigen-induced elevation of cyclic GMP level in plasma and its abolition in experimentally immunosuppressive mice

Intravenous injection of antigenic dose of sheep erythrocytes (SRBC) into mice caused a 150-200% increase in plasma cyclic GMP level within 5 min which continued for 60 min thereafter. Immunization by soluble antigens such as dextran sulfate and bovine serum albumin also elevated cyclic GMP level in plasma. The plasma cyclic GMP increased by antigen stimulation might be derived from immunocompetent cells. This assumption was supported by several lines of evidence as follows: (1) rat erythrocytes which are less antigenic for mice caused a relatively low response in terms of increase in cyclic GMP compared with SRBC, (2) this cyclic GMP response was abrogated in animals under immunosuppressive states where X-irradiated, azathioprine-treated or tumor-bearing mice were used. Mice pretreated with agents which block autonomic nervous system functions develop normal plasma cyclic GMP responses upon SRBC injection. Our observation in this report and many in vitro studies by other investigators suggested that plasma cyclic GMP elevated by antigen stimulation may be mainly derived from lymphoid cells as a consequence of the triggering of immune response.

Cooperative role of T lymphocytes and macrophages in anti-tumor activity of mice pretreated with schizophyllan (SPG)

Anti-tumor activity was studied in mice injected with Schizophyllan (SPG), a glucan produced by Schizophyllum commune Fries. SPG-injected mice rejected subcutaneously inoculated sarcoma-180 and the anti-tumor activity was shown to be mediated by host spleen and lymph node cells. The anti-tumor activity lasted as long as 60 days after the SPG administration as assessed by transfer of cells into normal recipients. Cells involved in anti-tumor activity were shown to be T lymphocytes since anti-tumor activity was diminished when lymph node cells from SPG-treated mice were treated with anti-Thy-1.2 sera plus complement, whereas cells passed through a nylon wool column retained the activity. Macrophages were also shown to be involved since administration of carrageenan or trypan blue into the host decreased the inhibition ratio of tumor growth. It was concluded that anti-tumor activity in SPG-treated mice was mediated by the cooperation of T lymphocytes and macrophages, thus the impairment of either function decreased anti-tumor activity.

Macrophage activities in sarcoma 180-bearing mice and EL4-bearing mice

Four types of macrophage activities were studied in sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice. Sarcoma 180 cells grow very slowly and do not metastasize, while EL4 cells grow very rapidly and metastasize rapidly to the liver. Chemotactic activity of macrophages was significantly reduced from an early stage in both sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice as compared with that in normal mice. Digestive activity, which was determined by following O2- production by chemiluminescence measurements was also reduced from an early stage in tumor-bearing mice, whereas no reduction of engulfment activity of microorganisms was observed until an advanced stage in both sarcoma 180-bearing mice and EL4-bearing mice. In contrast enhancement activity of macrophages in the blastogenic response of spleen lymphocytes to bacterial lipopolysaccharide was retained at the normal level at the early stage of the tumor graft and was reduced in later stages. These results suggest that activities of Ia-negative macrophages were at first depressed generally in tumor-bearing hosts and later the activities of Ia-positive macrophages were depressed by factor(s) which might be produced by tumor cells.

Enhancing effects of mini-cells prepared from Salmonella typhimurium on anti-tumor immunity in sarcoma 180-bearing mice

The enhancing effect of mini-cells of Salmonella typhimurium which do not contain chromosomal DNA on anti-tumor immunity in mice was studied. The growth of sarcoma 180 cells which were subcutaneously transplanted into ICR mice was significantly retarded in mice treated with Salmonella mini-cells at the same time or 7 days after S180 transplantation, while no or only a little growth inhibition was observed in mice treated 7 days prior to S180 transplantation. Treatment with mini-cells inoculation alone did not increase the survival time of mice that had received intraperitoneal transplants of S180 cells. However, a statistically significant increase of survival time was observed in mice treated with a combination of mini-cells and surgical resection of subcutaneous tumors when S180 cells were injected 7 days after the surgical resection. The injection of mini-cells restored macrophage chemotaxis in S180-bearing mice in which macrophage chemotaxis was greatly retarded but lymphocyte activity was not.

Immunopotentiation of tumor-bearing and toxohormone treated mice by human ceruloplasmin

Human ceruloplasmin was shown to have a restorative effect on the decrease of delayed hypersensitivity in sarcoma-180-bearing mice and of helper T-cell activity in cell-free. Ehrlich cancerous ascitic fluid-treated mice. Furthermore, it was also shown that ceruloplasmin augments the in vivo generation of alloreactive cytotoxic cell which consist of cytotoxic T-lymphocytes, cytotoxic macrophages and K cells.

Restorative effects of nandrolone decanoate on the mononuclear phagocyte system in tumor-bearing mice

The effects of nandrolone decanoate on the mononuclear phagocyte system (MPS) were examined in normal or tumor-bearing mice. Bactericidal activity against Listeria monocytogenes, carbon clearance test and leukocyte accumulation into the site of inflammation were depressed when viable cells of sarcoma-180 were inoculated subcutaneously into ddY mice 24hr before the assays. Pretreatment with nandrolone decanoate prevented such depression in tumor-bearing mice and increased MPS activities of normal or tumor-bearing mice above the level of non-treated normal mice. Nandrolone decanoate may be useful for the augmentation of antimicrobial activity in tumor-bearing hosts.

Effect of alternating administration of PS-K and carbazilquinone in tumor-bearing mice

In order to establish procedure for immunochemotherapy, the delayed hypersensitivity reaction (DHR) was investigated in tumor-bearing mice treated with an immunopotentiator, basidiomycetes polysaccharide (PS-K). DHR in the group given continuous administration of immunopotentiator was initially much stronger than that in the untreated group; however, the reactions were the same by the 4th week. The tumor-bearing group give intermittent administration of immunopotentiator retained strong DHR throughout the course, even though prolonged continuous administration failed to maintain such elevated immunoresponses. Alternating treatment with PS-K and carbazilquinone induced much higher DHR and much longer survival. The experimental results showed that continuous administration of an immunopotentiator led to decreasing immune responses in tumor-bearing mice. Intermittent administration of immunopotentiator was proved to be effective in restoring tumor suppression.

Role of delayed hypersensitivity and cytostatic macrophages in the rejection of an allo-transplantable murine tumor

Growth of an allo-transplantable tumor, sarcoma-180, was suppressed in ICR mice immunized with mitomycin C-treated tumor cells in Hanks' solution or heat-killed tumor cells mixed with complete Freund's adjuvant 7 days before subcutaneous inoculation of tumor cells. In those mice, cytotoxic lymphocytes were not detected in spleen, lymph node or peritoneal exudate cells before or after tumor inoculation. The activities of antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity were not found in sera. Cytostatic activity was detected in peritoneal glass-adherent cells, but not in glass-nonadherent cells. Such an activity was also conferred on normal peritoneal glass-adherent cells by incubation with the culture supernatant of lymph node cells from preimmune mice and tumor cells. Cytostatic macrophages mediated by lymphokine-producing lymphocytes may be at least one of the main effector mechanisms in resistance against such an allo-transplantable tumor line.

Specific and nonspecific immune resistance enhancing activity of staphage lysate

The immunopotentiating activity of staphage lysate (SPL) was evaluated in terms of its immune protection against lethal bacterial infection and its antitumor activity. Mice were pretreated weekly with 10(8) viable, Staphylococcus aureus, strain 18Z for 3 weeks (Induction), followed by intraperitoneal SPL injections (Elicitation) at various times in relation to infectious challenge or tumor implantation. Induction without elicitation, or elicitation alone failed to provide protection against Klebsiella pneumoniae infection and resulted in only 30-40% survival against homologous infection with pathogenic S. aureus type III, whereas combined induction and elicitation produced enhanced resistance induction and elicitation regimens resulted in 50% and 80-100% survival in mice inoculated with K. pneumoniae and S. aureus, respectively. SPL had no antitumor effect in mice implanted with median survival time resulting from induction and elicitation in animals implanted which Ehrlich's ascites. This enhancement of immune resistance may possibly be related to activation of thymus-modulated lymphocytes and macrophages by SPL.