Immunological resistance to L1210 leukemia induced by viable L1210/DTIC cells

Summary Permanent, drug-induced antigenic alterations, not detectable in parental cells and transmissible after the withdrawal of treatment with the drug, have been obtained in mouse lymphoma. Viable L1210/DTIC cells, because they are rejected by syngeneic animals and carry L1210-associated TAA, can elicit host resistance to a subsequent inoculum of parental L1210. Mice challenged with viable L1210/DTIC cells, following rejection, were more resistant than mice immunized with inactivated parental cells. Resistance was specific and related to the immunogenicity of the TAA of the original tumor line employed.Active immunization was potentiated by adoptive transfer of immune lymphocytes, as evidenced by marked improvement in animal survival. Also, the treatment of tumor-bearing animals with anticancer compounds in conjunction with immunological alteration may result in an improved therapeutic response. BCNU administered to immunized animals 6 days after challenge with parental tumor cells resulted in augmented host survival, possibly attributable to partial resistance of a secondary immune response to the drug and a late nadir of immunosuppression, occurring after the completion of therapeutic action. Cyclophosphamide given before immunization enhanced host survival to a subsequent challenge of L1210 leukemia, conceivably as the result of preferential inhibition of T suppressor cells.     

Characteristics of reovirus-mediated chemoimmunotherapy of murine L1210 leukemia

Summary We have previously demonstrated the ability of reovirus to function synergistically with chemotherapy in the treatment of murine EL-4 lymphoma. This study characterizes this treatment regimen in the therapy of L1210 leukemia. Animals with an estimated tumor burden of 10⁷ cells were treated with 9 mg/kg 1,3-bis(2-chloroethyl)-1-nitrosourea. Reovirus type 3, which had been quantitated either by particles or plaque-forming units (pfu), was administered 48 h after chemotherapy. Complete remission of tumor was observed in 80% of the animals which received either 10¹¹ particles or 10⁹ pfu of reovirus. Cured animals were resistant to challenge with homologous tumor, but were susceptible to challenge with heterologous tumor. Reovirus undergoes limited replication at the tumor site, and virus-specific antibody appears only after disappearance of reovirus-infected cells and virus from the ascites fluid. Reovirus appears to function therapeutically by inducing a tumor-specific cytolytic immune response.     

Selective in vivo antitumor effects of monoclonal anti-I-A antibody on B cell lymphoma

In a study of the biologic consequences of using monoclonal antibodies (mAb) with specificity for I-A for the elimination of an I-A-bearing B cell lymphoma, it was found that, despite the presence of I-A on a number of normal cell types and the propensity of anti-I-A to induce modulation of I-A and I-E on normal cells in vivo, a substantial effect on lymphoma growth could be measured in mAb-treated hosts. Unlike I-A on normal cells, tumor I-A failed to modulate in vivo, and 50% of animals could be cured of lymphoma by multiple doses of anti-I-A mAb. With a sensitive spleen tumor colonization assay, it was shown that neither T lymphocytes nor natural killer cells were involved in tumor elimination by anti-I-A mAb. In addition, C3 depletion only minimally affected the ability of anti-I-A to inhibit tumor growth, suggesting that complement-dependent lysis of tumor cells was not a major mechanism. Spleen cells from long term survivors of tumor challenge and mAb treatment functioned normally as antigen-presenting cells and in the recognition of alloantigens, and serum Ig levels were somewhat higher than in untreated mice; thus, such therapy can be carried out without compromising the immune reactivity of long term survivors.     

Suppression of cell-mediated immunity to challenge with P 815 mastocytoma in concanavalin A-treated mice

C57Bl/6 (B6) mice allogeneic to the P 815 mastocytoma tumor cell line when treated with concanavalin A prior to and at frequent intervals following challenge intraperitoneally with 10⁷ tumor cells showed a significant suppression of their cell-mediated immune response at 9–10 days when compared with untreated animals. Suppression of the immune response of mice syngeneic (DBA/2) or hybrid (BDF₁) to the tumor was also evidenced by increased mortality rates in concanavalin A-treated animals. The suppression of cell-mediated cytotoxicity observed in B6 mice treated with concanavalin A could be reversed by pretreatment with 20 mg silica injected intraperitoneally 7 days prior to challenge. These results suggest that macrophages play a significant role in the concanavalin A-induced immune suppression observed in this in vivo tumor-host system.     

Protection against gram-negative bacteremia in neutropenic mice with recombinant granulocyte-macrophage colony-stimulating factor

Granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulates production of neutrophils in bone marrow and may decrease the incidence of infection during neutropenia. We evaluated the protective role of recombinant GM-CSF against Pseudomonas aeruginosa challenge in neutropenic mice. CD-1 mice treated with cyclophosphamide on days 1 and 2 of the experiment were given GM-CSF (1, 2, or 4 micrograms/day) starting at day 4 of the experiment according to the following protocol: 1) 1 microgram of GM-CSF 2 hr and 24 hr after challenge; 2) 1 microgram 24 hr before challenge, 2 hr and 24 hr after challenge; 3) 2 micrograms injected 24 hr before and 2 hr after challenge; 4) 2 micrograms given 24 hr before and 2 micrograms given 2 hr and 24 hr after challenge; 5) 4 micrograms administered 2 hr and 24 hr after challenge; and 6) saline and bovine albumin controls. The number of blood neutrophils by days 4 and 5 was similar for GM-CSF-treated and untreated animals. Survival was significantly greater in animals given 2 micrograms of GM-CSF at 24 hr before and at 2 hr and 24 hr after challenge with Pseudomonas. Neutrophils and splenic macrophages obtained from GM-CSF-treated mice (2 micrograms/animal) produced significantly greater amounts of O2- (204 +/- 36 nmoles/10(5) cells) than controls (21 +/- 10 nmoles/10(5) cells). Additionally, neutrophils and macrophages from GM-CSF-treated mice killed significantly more bacteria (P. aeruginosa) in vitro and had a greater number of C3b and Fc receptors (78 +/- 12% and 89 +/- 8%) than did cells obtained from control animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

In vivo activity of lymphokine-activated macrophages in host defense against neoplasia

Purified splenic macrophage (M phi) from normal DBA/2J mice and mice bearing P815 tumors were examined for responsiveness to lymphokine (LK) preparations containing high concentrations of IFN-gamma. For both normal and tumor-bearing M phi, LK treatment induced morphologic changes and increased the percentage of Ia+ cells from 35 to 55%. Although neither population exhibited spontaneous cytotoxicity toward P815 targets, LK treatment induced considerable tumoricidal activity in tumor-bearing M phi (32 to 80% lysis) but only minimal activity in normal M phi (8 to 17% lysis). Subcutaneous injection of 1 X 10(6)P815 cells into DBA/2J led to progressive tumor growth and death of 100% of the recipients after 27 +/- 3 days. Injection of a 1:18 mixture of P815 with either LK-activated normal or tumor-bearing M phi caused tumor regression after 10 days, and prolonged life until 43 +/- 4 days with tumor-bearing M phi and 39 +/- 3 days with normal M phi. Untreated normal or tumor-bearing M phi were unable to cause the effect (30 +/- 2 days), and lymphocytes could not be substituted for M phi (25 +/- 3 days). In x-irradiated recipients, no effect of LK-activated M phi could be observed (control = 19 +/- 2 days; LK-activated tumor-bearing M phi = 21 +/- 3 days). In addition, administration of an admixture of LK-treated M phi and x-rayed tumor before challenge with viable P815 enabled the recipient to inhibit tumor growth and caused tumor necrosis with inflammatory cell infiltration of the tumor. These observations suggest that, in part, LK-activated M phi may interact in vivo with host-derived cellular components and enhance the immune reactivity of the host against the tumor.     

不同方式构建A20鼠B细胞淋巴瘤动物模型

目的探索多种方式构建A20鼠B细胞淋巴瘤动物模型及不同方式造模成瘤的特征。方法鼠源性B细胞淋巴瘤细胞株A20经皮下、尾静脉、脾脏和腹腔接种于同源BALB/c小鼠或先接种裸鼠成瘤后组织块移植BALB/c小鼠,观察动物成瘤时间、成瘤率、成瘤部位;取肿瘤组织和动物脏器行石蜡包埋、病理切片、HE染色观察其组织学特点。结果BALB/c鼠皮下注2×10^6组、2×10^7组和裸鼠瘤组织移植BALB/c小鼠组成瘤率皆为100%,成瘤时间分别为（15.29±3.2）d（、7.0±0.82）d和（6.29±0.49）d。BALB/c小鼠尾静脉注射2×106组、2×107组、脾脏注射组、腹腔注射组成瘤率分别为71.4%、100%、71.4%、14.3%,成瘤时间分别为（76.8±12.0）d、（26.1±7.99）d、（32.6±5.99）d和27 d。尾静脉成瘤部位播及肝脏、脾脏、胰腺、肾脏、食道、胃、肠、肠系膜、脑、淋巴结、骨、子宫、肌肉等多脏器和组织。BALB/c鼠A20成瘤组织学类似人弥漫大B细胞淋巴瘤。结论成功构建A20皮下移植瘤模型、血行播散性模型,为利用有免疫功能动物进行B淋巴瘤相关研究提供了实验平台。     

Complement activation determines the therapeutic activity of rituximab in vivo

Rituximab is an anti-CD20 chimeric mAb effective for the treatment of B-NHL. It can lyse lymphoma cells in vitro through both C- and Ab-dependent cellular cytotoxicity. The mechanism of action of rituximab in vivo is however still unclear. We have set up a new in vivo model in nonimmunodeficient mice by stable transduction of the human CD20 cDNA in the murine lymphoma line EL4. Animals injected i.v. with the EL4-CD20(+) lymphoma cells died within 30 days with evident liver, spleen, and bone marrow involvement, confirmed by immunohistochemistry and PCR analysis. A single injection of rituximab or the murine anti-CD20 Ab 1F5, given i.p. 1 day after the tumor, cured 100% of the animals. Indeed, at week 4 after tumor cell inoculation, CD20(+) cells were undetectable in all organs analyzed in rituximab-treated animals, as determined by immunohistochemistry and PCR. Rituximab had no direct effect on tumor growth in vitro. Depletion of either NK cells or neutrophils or both in tumor-injected animals did not affect the therapeutic activity of the drug. Similarly, rituximab was able to eradicate tumor cells in athymic nude mice, suggesting that its activity is T cell independent. In contrast, the protective activity of rituximab or the 1F5 Ab was completely abolished in syngeneic knockout animals lacking C1q, the first component of the classical pathway of C (C1qa(-/-)). These data demonstrate that C activation is fundamental for rituximab therapeutic activity in vivo.     

Lack of relationship of transplantation immunogenicity in C3H/He mammary carcinomas,with lymphoid hyperplasia and radiation-induced growth enhancement

Summary The therapeutic use of (a) radiation-inactivated tumor cells, (b) Bacillus Calmette-Guérin (BCG), and (c) heparinized plasma from normal mice to reduce radiation-induced impairment of existing antitumor resistance was investigated in female C3H/He hosts of syngeneic mammary carcinoma implants. The mice, which had been moderately presensitized 50 days before challenge, were given 300 rad whole-body irradiation at various times up to the day of challenge and 3 days after. Irradiated presensitized and irradiated unsensitized animals were maximally immunodepressed 1–2 weeks after exposure. The levels of resistance seen in unirradiated presensitized and in unirradiated unsensitized controls were recovered by irradiated presensitized and by irradiated unsensitized mice in about 3 and 4 weeks, respectively. Repeated injections of radiation-inactivated tumor cells were most effective in supporting the immune status of irradiated mice and in promoting an early recovery. Injections of BCG had only an insignificant effect. Injections of normal plasma was effective in reducing the immune suppression but did not promote an earlier recovery.     

Idiotypic vaccination as a treatment for a B cell lymphoma

To develop a model for the active immunotherapy of human B cell malignancy we vaccinated tumor-bearing animals with a well defined tumor associated Ag, the idiotypic Ig. The tumor used was the mouse B cell lymphoma BCL1, a highly malignant tumor in which transfer of a single tumor cell to a syngeneic mouse is capable of causing disease and eventual death. Varying doses (10(2) to 10(4] of BCL1 cells were given to mice on day 0 of the experiment, and treatment by active immunization was initiated on day 3. Immunization with purified, tumor-derived, idiotypic IgM (BCL1 IgM) coupled to keyhole limpet hemacyanin (KLH) was highly effective in treating mice challenged with 10(2) or 10(3) BCL1 cells, but less effective in mice that had received 10(4) tumor cells. Immunization with unconjugated BCL1 IgM showed no signficant therapeutic benefit. Coupling of the IgM to KLH led to higher levels of anti-idiotypic antibody after immunization; however, the higher levels were probably not responsible for the control of the malignancy as there was no correlation in healthy immunized animals between the levels of anti-idiotypic antibody, measured immediately before tumor challenge, and survival. This lack of correlation is due to the emergence of variant tumors in such protected mice. A more significant factor in the therapeutic advantage of KLH conjugation could be that immunization with BCL1 IgM-KLH led to an earlier induction of the anti-idiotypic response than immunization with BCL1 IgM and, as the BCL1, lymphoma divides rapidly, the speed of induction of the immune response may be important in outstripping tumor cell growth. Mice with BCL1 tumour showed some evidence of immunosuppression as indicated by a reduced ability to mount an immune response against KLH. Although it is not possible to model spontaneous human lymphoma accurately, the generation of a functional anti-idiotypic response capable o eliminating a malignant animal lymphoma in situ opens up the possibility of a limited trial of active immunotherapy in selected human patients.     

The effects of 50 Hz magnetic field exposure on dimethylbenz(α)anthracene induced thymic lymphoma/leukemia in mice

Several epidemiological investigations have suggested an increased incidence of lymphoma, leukemia, and brain tumor in residents living near power transmission lines. However, some observers failed to confirm such a positive correlation. To evaluate the effects of extremely low frequency (ELF) magnetic fields on leukemogenesis, an experimental animal model was used, in which thymic lymphoma/leukemia was induced by dimethylbenz(α)anthracene (DMBA) injected subcutaneously into the interscapular region of newborn mice within 24 h after birth. Beginning at the second week of age, 165 mice were exposed to 50 Hz magnetic field at 1 mT, 3 h/day, 6 days/week for 16 weeks, and 155 animals exposed to sham conditions. All surviving animals were killed by cervical dislocation at the age of 32 weeks and were examined pathologically. The results showed that the incidences of advanced thymic lymphoma, complicated with lymphomatous leukemia, were 21.8 and 23.9% in the two groups, respectively, without statistically significant differences. But dense metastatic infiltration by lymphoma cells into liver in the field exposure group greater (50%) than that in the sham-exposure group (16.2%) was observed (χ² = 9.847, P < 0.01). To determine whether ELF acts as a tumor promoter, further experiments are required. Bioelectromagnetics 18:360–364, 1997. © 1997 Wiley-Liss, Inc.     

Anti-idiotypic mechanisms involved in suppression of a mouse B cell lymphoma, BCL1

Immunization of BALB/c mice with idiotypic IgM rescued by hybridization from the syngeneic BCL1 lymphoma protects specifically against challenge with tumor cells, with 83% surviving greater than 100 days compared with controls (38 +/- 10 days). Spleens from long-term survivors (greater than 6 mo) with no macroscopically visible tumor, when examined with anti-idiotypic antibody, showed a range of apparently dormant tumor with BCL1 cells present at 2 to 50% of total. A spectrum of protection against tumor resulted from immunization, and tumor emerging in the period 53 to 173 days postpassage was investigated for expression of idiotype. It was found that cells from individual mice expressed variable amounts of idiotypic IgM at the cell surface, although it was always detectable in the intracellular compartment. Unlike typical BCL1 cells, tumor cells developing in immune spleens often secreted little idiotypic IgM either in vitro or in vivo. This modulation of expression and secretion of idiotype was detected even in the apparent absence of serum anti-idiotypic antibody. On passage of spleen cells from the long-term survivors into naive animals, BCL1 tumor developed and killed the recipients in a way indistinguishable from routine tumor passage. These tumor cells, however, both expressed and secreted IgM of the same idiotype as the original tumor. It appears therefore that tumor development in immunized mice is suppressed by a process that includes modulation but not selection of the tumor cell idiotypic determinants. Analysis of possible mechanisms of suppression revealed the presence of cytotoxic anti-idiotypic antibody at variable levels in sera of immunized mice, and splenic T cells that proliferated specifically in response to idiotypic IgM. Only low levels of cytotoxic T cells were found. Passive transfer studies demonstrated a major role for antibody in protection against tumor, with no significant enhancement by immune lymphocytes.     

Induction of effective immunity to Moloney murine sarcoma virus using monoclonal anti-idiotypic antibody as immunogen

We have isolated an anti-idiotypic mAb (RS1.1.3), which recognizes an idiotope present on several IgM mAb specific for Moloney murine leukemia virus (M-MuLV)-determined cell surface Ag. The binding of RS1.1.3 to idiotypic antibody could be inhibited by specific Ag. Intraperitoneal immunization of mice with purified RS1.1.3 antibody-induced effective immunity against Moloney murine sarcoma virus challenge. A single injection of RS1.1.3 7 days before virus challenge resulted in a 27% reduction in tumor load compared to non-immune control mice challenged with the same dose of virus, whereas multiple injections of RS1.1.3 before virus challenge resulted in a 75% reduction in tumor load. The protective effect of anti-idiotype immunization appeared to be T dependent, because immunization of athymic mice had no effect on their susceptibility to tumor virus challenge. Administration of the anti-idiotypic antibody after virus inoculation caused an increase in tumor load of nearly 50% compared to non-immune controls. BALB/c mice immunized with RS1.1.3 developed anti-anti-idiotypic antibodies, as well as M-MuLV Ag-specific antibodies. Analysis of sera from RS1.1.3-immune mice subsequently challenged with Moloney murine sarcoma virus indicated an inverse relationship between tumor load and M-MuLV-specific serum IgG titers induced by the RS1.1.3 immunization. These results indicate that anti-idiotypic mAb may be used as immunogen to induce Ag-specific antibody responses, and to cause effective immunity to a retro-virus-induced tumor.     

1,3-Bis(2-chloroethyl)-1-nitrosourea (BCNU)/interleukin-2 chemoimmunotherapy of murine L1210 leukemia

Summary We have developed a chemoimmunotherapy regimen for the treatment of L1210-cell-induced ascites tumors in mice using a combination of sub-toxic doses of interleukin-2 (IL-2) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU). BCNU is administered intraperitoneally 4 days after tumor implantation and followed 2 days later by single doses of human recombinant IL-2 for 3 consecutive days. An optimum survival of 84% was achieved using 1500 U IL-2. Reduced survival was observed when lower or higher IL-2 dosages were used. No therapy resulted when heat-inactivated IL-2 was used or when IL-2 was used without chemotherapy. Surviving animals were resistant to L1210 leukemia but not P815 mastocytoma tumor challenge suggesting the combined BCNU/IL-2 therapy stimulated tumor-specific immunity.     

Experimental immunotherapy with NK-like cells

Summary Natural killer (NK) cell activity was generated in the spleen of C3H/HeN mice by i.p. administration of poly I:C, while i.p. injection of BCG primarily promoted the generation of NK-like cells in peritoneal exudates (PE). A single injection of 10 mg of BCG 9 days before s.c. challenge with the MBT-2 murine bladder cancer was found to induce a 45% protection against tumor take. However, a single injection of 100 g poly I:C 16 h before tumor cell challenge did not protect the animals against tumor take. Intratumoral injection of either PE cells from BCG-immunized or spleen cells from poly I:C-treated mice into mice developing tumor, was capable of suppressing tumor growth in vivo. The mean tumor diameters of these two experimental groups of animals on day 40 were significantly smaller (P<0.005) than in the controls, and they survived approximately 10 days longer than the controls. Since this in vivo tumor suppressive effect by the lymphoid cell population correlated with the increase in NK-like cell activity assayed in vitro, and most of the adherent cells had been removed before injection, it is suggested that the antitumor function of the lymphoid cell population may be mostly due to the presence of activated NK or NK-like cells. These results support the concept of NK therapy for cancer.This study was supported by a grant from the Cancer Research Institute of New York     

CD4+CD25+ T regulatory cells dominate multiple immune evasion mechanisms in early but not late phases of tumor development in a B cell lymphoma model

Tumors use a complex set of direct and indirect mechanisms to evade the immune system. Naturally arising CD4(+)CD25(+)FoxP3(+) T regulatory (Treg) cells have been implicated recently in tumor immune escape mechanism, but the relative contribution of these cells to overall tumor progression compared with other immune evasion mechanisms remains to be elucidated. Using the A20 B cell lymphoma as a transplantable tumor model, we demonstrate that this tumor employs multiple direct (expression of immunoinhibitory molecule PD-L1, IDO, and IL-10, and lack of expression of CD80 costimulatory molecule) and indirect (down-regulation of APC function and induction of Treg cells) immune evasion mechanisms. Importantly, Treg cells served as the dominant immune escape mechanism early in tumor progression because the physical elimination of these cells before tumor challenge resulted in tumor-free survival in 70% of mice, whereas their depletion in animals with established tumors had no therapeutic effect. Therefore, our data suggest that Treg cells may serve as an important therapeutic target for patients with early stages of cancer and that more vigorous combinatorial approaches simultaneously targeting multiple immune evasion as well as immunosurveillance mechanisms for the generation of a productive immune response against tumor may be required for effective immunotherapy in patients with advanced disease.     

The role of the peritoneal cavity in successful treatment of a murine lymphoma with chemotherapy and non-specific immunostimulation

Summary The influence of the route of administration and treatment schedule of a yeast immunoadjuvant, Candida albicans (CA) on the degree of success achieved with an immunochemotherapy regimen in a virus-induced murine lymphoma has been evaluated. To this end, histocompatible CD2F1 mice received IP or IV inoculations of LSTRA lymphoma cells and were subjected to various treatments with inactivated CA and bis, 1, chloroethyl nitrosourea (BCNU).The results showed that CA may significantly increase the antitumor efficiency of BCNU when (a) the tumor is inoculated IP and not IV; (b) CA is administered before (on day –14) and after (on days +1 and/or day +8) LSTRA challenge; (c) CA is given IP as a post-tumor treatment.To ascertain whether the immunoadjuvant effect was anatomically restricted to the peritoneal cavity (PC), spreading of IP injected lymphoma was studied by means of LSTRA cells labeled with 3–5iodo-deoxyuridine ¹²⁵I (¹²⁵IUdR) and tumor bioassay in spleen, lung, kidney, liver, and PC of recipient mice. The results showed that IP tumor challenge led to early (1 h) generalized neoplasia in both untreated and CA-pretreated hosts.Therefore, the combined antitumor effects of chemotherapy and CA are not restricted to the PC but rather the result of systemic immunity. In conclusion, in our system the PC seems to be a preferential site for eliciting generalized antilymphoma host responses markedly amplified by selected schedules of immunoadjuvant administration.     

Feeding history and obese-prone genotype increase survival of rats exposed to a challenge of food restriction and wheel running

We hypothesized that obese-prone genotype and history of food restriction confer a survival advantage to genetically obese animals under environmental challenge. Male juvenile JCR:LA-cp rats, obese-prone and lean-prone, were exposed to 1.5 h daily meals and 22.5-h voluntary wheel running, a procedure inducing activity anorexia (AA). One week before the AA challenge, obese-prone rats were freely fed (obese-FF), or pair fed (obese-PF) to lean-prone, free-feeding rats (lean-FF). Animals were removed from protocol at 75% of initial body weight (starvation criterion) or after 14 days (survival criterion). AA challenge induced weight loss in all rats, but percent weight loss was more rapid and sustained in lean-FF rats than in obese-FF or obese-PF animals (P < 0.04). Weight loss was significantly higher in obese-FF rats than obese-PF rats, 62% of which achieved survival criterion and stabilized with zero weight loss. Obese-PF rats survived longer, on average (12.0 ± 1.1 day) than obese-FF (8.2 ± 1.1 day) and lean-FF rats (3.5 ± 0.2 day) (P < 0.02). Wheel running increased linearly in all groups; lean-FF increased more rapidly than obese-FF (P < 0.05); obese-PF increased at an intermediate rate (P < 0.02), and those rats that survived stabilized daily rates of wheel running. Prior food restriction of juvenile obese-prone rats induces a survival benefit beyond genotype, that is related to achievement of homeostasis. This metabolic adaptive process may help explain the development of human obesity in the presence of an unstable food environment which subsequently transitions to an abundant food supply.     

Growth performance and immune responses in chickens after challenge with lipopolysaccharide and modulation by dietary different oils

The study was conducted to investigate the effects of different oils on growth performance and immune responses of chickens after challenge with lipopolysaccharide (LPS). A total of 288 chickens were assigned in a 2 × 2 factorial design. Factors were dietary fat type (4.5% maize oil or 4.5% fish oil) and immunological challenge (LPS or saline). At 20 days and 27 days of age, chickens were injected intraperitoneally with either 1 mg/kg body weight of LPS or sterile saline. LPS decreased feed intake from 21 days to 28 days of age and body-weight gain from 21 days to 42 days of age. Fish oil improved feed-conversion efficiency of chickens after LPS challenge for the first time. Fish oil supplementation decreased lymphocyte proliferation (21 days: P < 0.0001; 28 days: P < 0.0001) and the ratio of CD3+CD4+/CD3+CD8+ (21 days: P = 0.0479; 28 days: P = 0.0009) after LPS challenge. LPS challenge increased the levels of interleukin-1 (IL-1) (21 days: P < 0.0001; 28 days: P = 0.0030), IL-6 (21 days: P < 0.0001; 28 days: P = 0.0001) and tumor necrosis factor-α (TNF-α) (21 days: P = 0.0008; 28 days: P = 0.0018). And fish oil alleviated the elevations in the production of IL-6 (21 days: P = 0.0359; 28 days: P = 0.0302) and TNF-α (21 days: P = 0.0055; 28 days: P = 0.0391) induced by the LPS challenge. Fish oil alleviated the mRNA abundance elevation of nuclear factor kappa B (NFκB) (21 days: P = 0.0079; 28 days: P = 0.0017) after LPS challenge. These results showed that fish oil acts as an anti-inflammatory agent, which may be associated with down-regulation of the activated immune system. The results of pro-inflammatory cytokines and mRNA abundance results suggested that fish oil might alleviate the elevation of IL-6 and TNF-α induced by LPS through down-regulating NFκB expression.     

Idiotype vaccination against murine B cell lymphoma. Inhibition of tumor immunity by free idiotype protein

A murine B cell lymphoma (38C13) was used as a model to study the induction of idiotype (Id)-specific tumor immunity. Immunization of syngeneic mice with Id protein derived from the tumor resulted in the production of anti-Id antibodies by the host and in the induction of a state of resistance to tumor growth. Tumor immunity could be established only if the Id protein was conjugated to a strongly immunogenic carrier protein such as keyhole limpet hemocyanin or thyroglobulin, and if the conjugate was administered at least 1 week prior to tumor challenge. Free Id protein, such as that present in tumor bearing animals, was found to inhibit tumor immunity in a dose-dependent manner. Although tumor immunity could be induced in animals with pre-existent serum Id protein, the expression of the immune state was inhibited by the presence of the soluble protein.