A comparison of the Antileukaemic Effects of Recombinant Human Tumour Necrosis Factor-alpha and its Muteins on Leukaemia L1210 and Leukaemia P388 in Mice

We investigated the influence of recombinant human tumour necrosis factor alpha (TNF-alpha) and its derivatives termed muteins III, V, VI-in which the first 3 to 7 amino acids of native TNF-alpha have been replaced-on the survival time of mice inoculated with leukaemia L1210 or leukaemia P338. TNF-alpha prolonged the survival of mice with leukaemia L1210 but did not have any therapeutic activity in leukaemia P388-bearing mice. Muteins-treated mice with leukaemia P388 lived longer than animals receiving TNF-alpha, while those inoculated with leukaemia L1210 did not show any significant prolongation of life compared with the TNF-alpha treated group. The results presented in this report indicate that the antileukaemic activity of TNF-alpha is governed at least in part by the nature of the N-terminal amino acids.     

Non-cytotoxic activity of pyran copolymer-induced macrophages associated with potentiation of tumour vaccine in recipient mice

Summary Mice inoculated with both L1210 murine tumour vaccine and pyran copolymer were more resistant to L1210 than those inoculated with either of these agents alone. Rabbit anti-mouse thymocyte globulin and silica reduced the augmented resistance of these mice, suggesting the involvement of activated anti-tumour T cells and macrophages in the augmented resistance. We studied the activation of these two cells separately and examined the possible contribution of pyran copolymer-induced peritoneal cells to the augmented resistance to an inoculation of live tumour. Pyran copolymer-induced peritoneal cells endowed the tumour vaccine-primed mice, but not unprimed mice, with resistance to implanted L1210 and, among those peritoneal cell populations, macrophages but not T cells were responsible for this effect since the activity was associated with a cell population which was (1) adherent to nylon wool columns, (2) sensitive to silica and (3) insensitive to anti-Thy 1.2 antibody plus complement. The pyran copolymer-induced peritoneal cells had very little antiproliferative activity when tested against L1210 in vitro and mice inoculated with these peritoneal cells did not survive a challenge of live L1210 cells much longer (<1 day) than L1210 inoculated control mice. Furthermore, the survival of L1210 vaccine-primed mice inoculated with one-tenth the amount of live L1210 (10²) was still much shorter than that of mice primed with L1210 vaccine plus pyran copolymer and challenged with ten times as many (10³) live L1210 cells. Therefore, direct tumouricidal activity was probably not a major factor in the in vivo immunological augmenting activity of the pyran copolymer-induced macrophages.     

Factors responsible for immune resistance to L1210 murine leukemia in hyperimmune mice

Summary The serum of mice hyperimmune to L1210 leukemia was cytotoxic to L1210 cells and, to a much lesser extent, to P388 cells in the presence of complement. However, it did not suppress in vitro growth of L1210 cells, nor did it endow a recipient mouse with immunity to inoculated L1210 cells. This indicates that the serum did not play a significant role, if any, in immune protection of hyperimmune mice.Spleen and peritoneal exudate cells of hyperimmune mice suppressed the in vitro growth of L1210 but not of P388 cells. This is consistent with the fact that hyperimmune mice did not survive the inoculation of P388 cells. The immunocytes failed to suppress the in vitro growth of L1210 cells when preincubated with anti-Thy-1.2 antisera and complement. This, together with the finding that cell populations not adherent to a plastic dish suppressed in vitro growth of L1210 cells, indicates that T cells of immune spleen and peritoneal exudate cell populations were the effectors that suppressed in vitro growth of L1210 cells. Hyperimmune mice lost their immune protection in vivo following the administration of anti-thymocyte antisera, but not with carrageenan or silica, which resulted in the lethal growth of the inoculated L1210 cells. This indicates that T cells were in vivo effectors in immune protection.Hyperimmune spleen T cells endowed a recipient with immunity to L1210 leukemia when transferred in vivo. This confirmed the above results and suggests the applicability of immune cells in an adoptive immunotherapy approach.     

Thymosin α1 restores NK-cell activity and prevents tumor progression in mice immunosuppressed by cytostatics or X-rays

The effect of thymosin against tumor progression was examined in mice immunosuppressed by cytostatics or X-ray irradiation. When pretreated with cytostatic agents, such as 5-fluorouracil (5-FU) or BCNU, or by X-ray, and then inoculated with P388 or L1210 leukemias, mice died rapidly within a few days. In these systems, thymosin alpha 1 given concomitantly with the cytostatic agents or after X-irradiation prevented rapid death and extended survival, although the mice eventually died with leukemia like normal mice inoculated with cells of the same tumor. Rapid death in the 5-FU-treated mice was also prevented by adoptive transfer of spleen cells from the donor mice if these had been treated with 5-FU plus thymosin alpha 1, but not if they had received 5-FU alone. However, the restorative activity of the donor spleen cells was abrogated by treatment with anti-asialo GM1, but not by treatment with anti-Thy 1 or anti-mouse Ig serum, suggesting that the effector cells in the spleen are NK cells. In fact, thymosin alpha 1, when given concomitantly with 5-FU or after X-irradiation, maintained the NK activity of spleen, which was damaged by treatment with 5-FU or X-irradiation alone. The present study indicates that thymosin alpha 1 exerts a preventive activity against progression of leukemias at least in part through an effect on NK cells or their progenitor cells.     

Efficacy and toxicity elicited by recombinant interferons alpha and gamma when administered in combination to tumor-bearing mice

Administration of rHuIFN-alpha A/D and rMuIFN-gamma as single agents to tumor-bearing mice resulted in a dose-related antitumor effect in each of the six models studied. When the IFNs were given in combination, the effects varied between the tumor systems. No increase in efficacy was seen in mice bearing B16-F10 melanoma or M5076 reticulum cell sarcoma while additive antitumor activity was shown in the KA31 fibrosarcoma and P388 leukemia systems. Mice inoculated with L1210 lymphoma or colon 38 carcinoma, however, revealed enhanced efficacy which was greater than additive. The data also reveal that combination of IFNs alpha and gamma administered to normal and tumor-bearing mice resulted in toxicity which was not predicted by the appropriate doses of the single agents. These studies suggest that combination of IFNs alpha and gamma may provide greater therapeutic utility than the single agents and underscore the need for additional, carefully designed preclinical and clinical efforts.     

Structure-antitumour activity relationships for new platinum complexes

Fourteen platinum (Pt) coordination complexes with different ligands, which include both Pt(II) and Pt(IV) complexes, were prepared, characterized and tested for their in vitro cytotoxic effects on KB cells and for their antitumour activity against some tumour systems (L1210 and P388 leukaemia, ADJ/PC6A plasma cell tumour and Yoshida sarcoma).The majority of the ligands were derivatives of aniline or pyridine, but complexes with tranylcypromine, guanethidine and octodrine were also synthetized.Depending on cytotoxicity the Pt-compounds could be divided into 3 groups. The compounds with a high cytotoxicity (ED₅₀ = 0.1–1 μg/ml) were also active against L1210 and P-388 leukaemia; a correlation between cytotoxicity and antitumour activity was not always observed.In these complexes the oxidation state of the Pt appears to be critical for their activity.     

In vivo growth kinetics of P388 and L1210 leukemias

The P388 lymphocytic leukemia and the L1210 lymphoid leukemia are used as test systems for putative cytotoxic drugs. These leukemias are also used to investigate the perturbation of cell cycle progression of various chemical compounds in more detail. There is little information on the normal growth kinetics in vivo of these leukemias. In the present report we therefore present the results from growth kinetic studies of P388 and L1210 leukemic cells growing in ascites form in mice. We used 3H-TdR autoradiography, DNA flow cytometry and the stathmokinetic method. During exponential growth both leukemias showed a growth fraction of unity. Whereas no significant cell loss was observed during the early growth phase of P388 cells, cell loss was indicated by a discrepancy between potential and actual doubling times during exponential growth of L1210 cells. During the phase of growth retardation, the proportion of G1 and G2 cells increased at the expence of a reduced S phase fraction in the P388 leukemia, whereas only small changes in cell cycle distributions were seen with time after inoculation of L1210 cells. An increasing discrepancy in the reduction of the S phase fraction and the 3H-TdRLI was seen in the P388 cells with time after inoculation. Thus, a majority of P388 cells with S phase DNA content were unlabelled during the late phase of growth restriction, indicating resting cells in S phase. A good correlation was found between the 3H-TdR LI and S phase fraction throughout the life history of L1210 cells, revealing considerable differences in in vivo growth kinetics between the two leukemias. Such differences should be considered when evaluating test results.     

Antitumor effect of lysine-isopeptides

Isopeptides (ε-peptides) of lysine, with a given Mw and low polydispersity (10–400 units), were synthesized to study the relationship between their chemical structure and biological effect. The designed compounds were of high purity, low polydispersity and high stereochemical purity. The effect of the compounds was tested on a human erythroleukemia cell line (K-562) and on four transplantable mouse tumors (L1210 lymphoid leukemia, P38 macrophage derived tumor, Ehrlich ascites carcinoma, Lewis lung tumor /LLT/). In case of the L1210 and P388 tumors and the Ehrlich carcinoma, survival of the animals was used as an indicator of the effect. In case of the Lewis lung tumor, the number and size of metastases in the lung and/or liver of treated and untreated mice were used as indicators. The polymers of polymerisation degree 80–120 (Mw 10.2–15.4 KD) showed the strongest antiproliferative effect both on K562 cells and the tumors growing in vivo. This effect was manifest with a significantly higher survival rate as compared to the control (L1210, P38, Ehrlich ascites), furthermore, by a decrease in the number and size of liver and lung metastases (LLT).     

Antitumor activity of equinatoxin.

Equinatoxin, a highly basic protein extracted from Actinia equina, causes an increase in the survival time of mice bearing the ascitic form of Ehrlich carcinoma, whereas it has no effect on L1210 leukaemia. When tested for in vitro cytotoxicity by the dye exclusion test, it shows a potent activity on both tumour cell lines, with ED50 of a few ng/ml. Higher concentrations produce an extensive lysis of the cells. The cytotoxic effects of Equinatoxin are inhibited by phospholipids, thus suggesting that its mechanism of action may be related to interactions with lipids or other charged components of cell membrane. The observed lack of in vivo activity against L1210 leukaemia presumably is due to poor systemic absorption of the protein and/or neutralization by serum factors.     

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.     

Ricin A-chain conjugated with monoclonal anti-L1210 antibody

Summary In studies of antitumor antibody-cytotoxic agent conjugates as potential antitumor agents with improved tumor specificity, the toxic subunit A-chain of ricin was conjugated with a monoclonal antibody to a tumor-associated antigen expressed weakly on murine leukemia L1210 cells and strongly on L1210/GZL cells, a guanazole-resistant subline of L1210, employing N-succinimidyl 3-(2-pyridyldithio)propionate as cross-linking agent. The conjugate (anti-L1210 conjugate) exhibited a potent concentration-dependent cytotoxicity against cultured L1210/GZL cells, and inhibited cell growth at concentrations over 0.8 g/ml. The conjugate killed all L1210/GZL cells at a concentration of 100 g/ml. Neither nonimmune conjugate similarly prepared from mouse nonimmune IgG nor unconjugated anti-L1210 IgG alone showed cytotoxicity against L1210/GZL cells. When (BALB/c×DBA/2)F₁ mice inoculated with 1 × 10⁵ L1210/GZL cells were treated with IP injections of 27 g anti-L1210 conjugate 1 h and 5 days after tumor cell inoculation, a life-prolonging effect was observed. [Lifespan in treated animals as percentage of that in controls (T/C)=146%]. However, when the dose per injection was increased to 50 g per mouse, survival was the same as in the control group. Postmortem examination of mice that had been treated with 50 g anti-L1210 conjugate revealed lesions with necrosis and hemorrhage in the liver parenchyma and the intestinal epithelium, respectively. A similar toxic effect on the host mice was also observed with nonimmune conjugate.     

Preparation of dihydrocarminomycin and a comparison of its antitumor activity with the activity of carminomycin]

A dihydro derivative of karminomycin was prepared using chemical reduction with potassium boron hydride. When dihydrokarminomycin was administered intravenously to healthy albino mice in a single dose it practically showed the same toxicity as karminomycin. However, unlike the latter dihydrokarminomycin induced the death of the animals at later periods of time. Studies on mice with transplantable tumours showed high antitumor activity of dihydrokarminomycin against lymphosarcoma L10-1, sarcoma 180, Garding-Passy melanoma, lymphoid leukosis L-1210 and lymphocytal leukosis P-388. In treatment of the mice with leukosis L-1210 and Garding-Passy melanoma dihydrokapminomycin was much inferior by its efficiency than karminomycin.     

Effect of levamisole on cytotoxic T-cell-mediated immune resistance to L1210 murine leukemia in hyperimmune mice

Summary The effect of levamisole (LMS) on T-cell-mediated antitumor immunity was examined in adult and aged mice hyperimmune to L1210 leukemia. The immune resistance of aged mice was depressed compared with that of adult mice, which almost completely rejected 5×10⁷ L1210 cells inoculated IP. A significant level of tumor-specific cytotoxicity was detected in the spleen cells of adult hyperimmune mice by the ⁵¹Cr-release assay after in vitro sensitization with mitomycin C-treated L1210 cells. This was mediated by cytotoxic T cells, since in vivo administration of antithymocyte serum or in vitro treatment of the spleen cells with anti-Thy 1.2 antibody and complement abrogated the cytotoxicity completely. In aged mice, however, cytotoxic T-cell activity was lower although the animals were immune to L1210.Administration of LMS (0.38 mg/kg) restored the depressed cytotoxicity of aged mice to the level seen in adult mice. Furthermore, in adult hyperimmune mice LMS augmented T-cell-mediated cytotoxic activity and restored the reduced cytotoxicity caused by in vivo administration of antithymocyte serum. These results indicate that LMS was effective in augmenting T-cell-mediated tumor immunity in immunologically competent or deficient hosts.     

软骨多糖对L1210白血病小鼠生长抑制作用的研究

目的:研究软骨多糖对L1210白血病小鼠的生长抑制作用,并探讨其抑瘤作用机理。方法:建立DBA/2小鼠L1210腹水瘤模型,将小鼠分为对照组、低剂量组、中剂量组和高剂量组进行实验,通过腹腔注射软骨多糖治疗,每天称重并记录小鼠的生存时间,计算生命延长率。于0h、24h、48h、72h抽取治疗组小鼠的腹水瘤细胞进行细胞周期的分析;采用常规HE染色观察细胞形态学变化;应用免疫荧光方法检测BCL-2和BAD蛋白表达变化,以进一步探讨软骨多糖的抑瘤机制。结果:软骨多糖可以明显提高DBA/2小鼠的生存率;细胞形态学观察可见细胞出现细胞浆浓缩、核固缩及凋亡小体等现象;软骨多糖作用后的L1210细胞,其细胞周期被阻遏于Go/G1期,24h-48h凋亡率迅速上升;Bad蛋白的表达水平于给药24h-72h后升高,抗凋亡基因Bcl-2表达下降。结论:软骨多糖可能通过影响肿瘤细胞周期和Bad、Bcl-2蛋白的表达来诱导L1210细胞凋亡,并显著抑制肿瘤细胞的生长,延长DBA/2小鼠的生存时间,是一种新型的抑癌活性物质。     

Synergistic effects of Actinobacillus suis cells in combination with 5-fluorouracil on mice bearing murine L1210 leukemia cells

 The mean survival rates of female BDF₁ mice transplanted intravenously (i.v.) with murine L1210 leukemia cells were significantly prolonged by intraperitoneal (i.p.) pretreatment (before i.v. transplantation) or by i.p. pre- and post-treatment (before and after the i.v. transplantation) with heat-killed Actinobacillus suis cells ATCC 15557 (AS 15557) alone, as compared with untreated L1210-leukemia-cell-bearing control mice. However, significant prolongation of the mean survival rates was not elicited by the i.p. post-treatment with AS 15557 alone. When 5-fluorouracil (5-FU) was applied i.p. to mice receiving post-treatment with AS 15557 alone, the mean survival rates of the L1210-leukemia-cell-bearing mice were significantly prolonged. The antileukemic action of AS 15557, alone or in combination with 5-FU, against L1210 leukemia was superior to that of a streptococcal preparation (OK-432) and was almost the same as of bacillus Calmette-Guérin with or without 5-FU. The results suggest the possibility that the synergism of AS 15557 in combination with 5-FU may be dependent on the relationship between the indirect immunological function of AS 15557 and the direct cytotoxic action of 5-FU on L1210 leukemia cells. Received: 5 December 1996 / Accepted: 28 March 1997     

Synthesis and Biologic Evaluation of 8-Substituted Derivatives of Nebularine (9-β-D-Ribofuranosylpurine)

Abstract

A series of 8-substituted purine ribonucleosides were prepared from 2′, 3′, 5′-tri-O-acetyl-8-bromoadenosine and evaluated for cytotoxicity and antiviral activity. Four of these nucleosides (6b-9b) were significantly toxic to both HEp-2 and L1210 cells in culture but the most cytotoxic one (9b) was inactive against the P388 leukemia in mice. None of these nucleosides showed significant antiviral activity against Herpes Simplex 1 or 2, vaccinia, or influenza A.     

Antitumoral cyclic peptide analogues of chlamydocin

A series of cyclic tetrapeptides bearing the bioactive alkylating group on an ε-amino-lysyl function have been examined for their antitumoral activity on L1210 and P388 murine leukemia cell lines. One analogue belonging to the chlamydocin family and bearing a β-chloroethylnitrosourea group was found to be potent at inhibiting L1210 cell proliferation and had a higher therapeutic index than the reference compound bis-β-chloroethylnitrosourea (BCNU) on the in vivo P388-induced leukemia model.     

Development of host-dependent high-grade tumor-specific immunity through a novel mechanism triggered by the Lyt-2+ tumor-specific T cell clone (K7L) that induces temporal growth of L1210 leukemia-K7L-variant

When a murine leukemia L1210-specific Lyt-2+ T cell clone, K7L, was injected i.p. into CD2F1 mice together with L1210, the normal growth of L1210 in the peritoneal cavity of the mice at the early stage (days 0 to 5) was strongly inhibited, but L1210 grew progressively at the middle-stage (days 5 to 10), and then was rejected at the late stage (days 10 to 20). The mice thus survived for long times (more than 60 days), whereas the normal control injected with L1210 alone died within 14 days. The L1210 that grew at the middle stage in mice initially inoculated with L1210 together with K7L was a K7L-insensitive (K7L-) variant. All of eight tumor clones established from L1210-K7L- by limiting dilution was insensitive to the antitumor activity of K7L, and this property of tumor clones was stable after repeated in vitro passage. The initial depression of the L1210 growth by K7L followed by growth and rejection of the variant L1210-K7L- by the host T cell activity was then found to prepare a strong, long-lasting (more than 3 mo) immunity to protect mice against the high-dose (10(7) cells per mouse) challenge of original L1210. Corresponding to this result, definite tumor (L1210)-specific cytotoxic T lymphocyte (CTL) activity against both variant and original L1210 targets was developed by antigen (L1210) restimulation in the culture of spleen cells from these mice, but was not increased to a detectable level before L1210-K7L- variant started to grow. It was suggested that the 1210-K7L- variant and the original L1210 should have the common tumor-specific antigen that was independent of the K7L-reactive antigen, and that original L1210, whose growth was retarded by K7L, primed the host with the common antigen to be enormously boosted by the subsequently growing L1210-K7L- variant.     

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.     

Influence of 60-hertz magnetic fields on leukemia

Female DBA/2 mice at 8 weeks of age were implanted with P388 leukemia cells in groups of ten mice and exposed to a 60-Hz 1.4-μT, 200-μT, or 500-μT magnetic field 2-3 hours after the implant for 6 hours daily, 5 days/week until all the exposed P388-treated and nontreated mice died. Parallel exposed groups of non-P388-treated mice and P388-treated mice exposed at 0 μT were included for study. No statistically significant differences (P > .05) in survival, spleen weight, or body weight resulted between P388-treated or nontreated mice from exposure to the magnetic field. No effect on the incidence or progression of P388 leukemia was apparent.