Induction of tumor-inhibitory macrophages with a novel synthetic immunomodulator, 3,6-bis(2-piperidinoethoxy)acridine trihydrochloride (CL 246,738)

3,6-bis(2-piperidinoethoxy)acridine trihydrochloride (CL 246,738) has been investigated for its immunomodulatory effect on murine macrophages. Incubation of macrophages harvested from the peritoneal cavities of normal mice with the compound for 48 to 72 hr rendered these cells inhibitory to the growth of tumor cells in vitro. Activation of tumor-inhibitory macrophages occurred over a range of concentrations (0.025 to 0.1 micrograms/ml) producing no direct inhibitory effects on tumor cells. Treatment of effector cells with carrageenan abrogated the effect, whereas treatment with anti-Thy-1.2 antibody and C did not, suggesting that the primary effectors were macrophages rather than T lymphocytes. These activated macrophages also manifested in vitro tumor cytolysis. In vivo studies indicated that peritoneal macrophages from mice treated with single oral doses of 100 to 400 mg/kg of the compound were also inhibitory to tumor cell growth in vitro. Effector macrophages became demonstrable in mice as early as 1 day after drug administration, reached peak activity at day 12, and disappeared by day 31, indicating a rapid onset but long-persisting effect. The tumor cytostatic activity of these macrophages was augmented by endotoxin at the dose of endotoxin that, in itself, had no effect. The addition of protease inhibitors, N-alpha-p-tosyl-L-lysine chloromethyl ketone and aprotinin, to cultures markedly diminished the cytostatic effect, suggesting that the release of neutral protease(s) could account for the inhibitory effects of the macrophages. On the other hand, hydrogen peroxide and arginase seemed excluded as the mechanism of action because the effect was not sensitive to treatment with catalase and exogenous arginine. The present findings indicate that CL 246,738 is an orally active immunopotentiator capable of inducing tumor-inhibitory macrophages both in vitro and in vivo.     

Role of natural killer cells in the modulation of primary antibody production by purine nucleosides and their analogs.

Previous results from this laboratory demonstrated that treatment of mice with the adenosine analog tubercidin (Tub) reduced natural killer (NK) cell activity while stimulating antibody production whereas the deoxyadenosine analog, 2-fluoroadenine arabinoside-5'-monophosphate (FaraAMP), produced opposite effects; i.e., it stimulated NK cell activity at doses that inhibited antibody formation (Cancer Res. 48, 4799, 1988). Since NK cells have been reported to play a suppressor role in immunoglobulin induction, it was hypothesized that the actions of Tub and FaraAMP on antibody production occurred secondary to their opposing effects on NK cells. To test this hypothesis, abilities of these nucleoside analogs to modulate primary antibody response to sheep red blood cells were evaluated in a C57BL/6 mutant mouse lacking NK cell activity (the beige mutation. C57BL/6-bg/bg). As previously found with C3H/He mice. NK cell activity was inhibited (Tub, doses 2-6 mg/kg/day for 3 days) or stimulated (FaraAMP, doses 75-250 mg/kg/day for 3 days) in heterozygous mice C57BL/6-bg/+. In support of the hypothesis, these nucleosides had no effect on primary antibody formation in the homozygous mutant mice at doses that clearly stimulated (Tub) or inhibited (FaraAMP) this immune response in heterozygous C57BL/6-bg/+ animals. This results was corroborated in C57BL/6 wild-type mice by abrogation of NK cell activity using a monoclonal antibody to the NK cell surface glycophisingolipid, ganglio-n-tetraosylceramide. We conclude that under the conditions of drug administration, modulation of primary antibody formation by Tub and FaraAMP in mice occurs indirectly via NK cells. Similar experiments using the potent ADA inhibitor, deoxycoformycin, indicated that its enhancement of primary antibody formation is independent of NK cell activity.     

Immune responsiveness and phagocytic activity of macrophages in streptozotocin (SZ)-induced diabetic mice

We succeeded in inducing different severities of diabetic state in C3H male mice by repeated intraperitoneal injections of various doses of SZ. SZ-induced diabetic mice were divided into four groups as follows: Group A, B, C and D. SZ, respectively, 3, 5 doses of 45 mg/kg, 5 doses of 60 mg/kg on consecutive days and one of a dose of 200 mg/kg BW. The degree of hyperglycemia and glycosuria were mild in group A and D. Group B was moderate and group C severe with ketonuria and loss of body weight. We investigated the immune response to anti-sheep red blood cells (SRBC) and the phagocytic activity of macrophages in the above mentioned various SZ-induced mice. Antibody forming activities (values of anti-SRBC plaque-forming cells (PFC) and serum agglutinin) were markedly depressed in all of SZ-diabetic groups. The degree of the suppression of antibody response to SRBC in SZ-diabetic mice corresponded with the severity of the diabetic state (C greater than B greater than A = D). However, the phagocytic activity of peritoneal macrophages in SZ-diabetic mice was as high as or higher than that in normal controls, using both latex beads and immune complex as test particles. Moreover, we observed that insulin treatment reversed the defect in the immune response in SZ-diabetic mice. These results indicate that the phagocytic activity of peritoneal macrophages was retained but the antibody response was impaired in the SZ-diabetic mice, and this suggested that the impaired antibody response may be a contributing cause of increased susceptibility to infections in a diabetic state.     

Antioxidant activity and low toxicity of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one

The aim of the present study was to evaluate the potential pharmacological and toxicological properties of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one (compound 1), an organoselenium compound. In vitro experiments showed that compound 1 presented a reduction in the lipid peroxidation induced by Fe2? in thiobarbituric acid-reactive species (TBARS) production, and in the generation of reactive species caused by Fe2?/malonate in DCFH-DA oxidation. The high dose (500 mg/kg) induced an increase on ALT but not on AST activity. Hepatic, but not cerebral, δ-ALA-D activity from mice treated with 500 mg/kg presented a significant inhibition. Brain catalase activity was significantly inhibited by 100 mg/kg whereas hepatic catalase activity showed a significant increase at all doses. Hepatic lipid peroxidation was diminished only at lowest dose (100 mg/kg) whereas for brain tissue, all doses induced a significant reduction in TBARS levels. Brain and liver ascorbic acid contents were increased only at highest dose of compound 1. Urea and creatinine levels were not significantly altered by treatments. This is a promising compound with antioxidant activity and low toxicity, suggesting the potential beneficial activity of compound 1 against oxidative damage in many parameters studied in rats and mice.     

Induction of interferon and activation of NK cells and macrophages in mice by oral administration of Ge-132, an organic germanium compound

After oral administration of an organic germanium compound, Ge-132 (300 mg/kg), a significant level of interferon (IFN) activity was detected in the sera of mice at 20 hr and it reached a maximum of 320 U/ml at 24 hr. This IFN activity was lost after heat- or acid-treatment, suggesting that the induced IFN is of gamma-nature. The molecular weight of this IFN was estimated to be 50,000 daltons by gel filtration. The NK activity of spleen cells was increased 24 hr after the oral administration of Ge-132, and cytotoxic macrophages were induced in the peritoneal cavity by 48 hr. In the mice receiving an intraperitoneal (ip) injection of trypan blue or carrageenan 2 days before oral administration of Ge-132, neither induction of IFN nor augmentation of NK activity occurred, and X-ray irradiation of mice also rendered the mice incapable of producing IFN, all indicating that both macrophages and lymphocytes are required for this IFN induction. Both NK and cytotoxic macrophages appeared 18 hr after ip administration of the induced IFN with a titer as low as 20 U/ml. These facts suggest that both the augmentation of NK activity and activation of macrophages in mice after oral administration of Ge-132 are mediated by the induced IFN.     

Impacts of functional oligosaccharide on intestinal immune modulation in immunosuppressive mice

In order to research the role of soybean oligosaccharides (SBOSs) on improvements in the microenvironment of intestinal flora and immune function of cyclophosphamide (CTX) immunosuppressive mice. Via giving intragastric administration of Soybean oligosaccharide (SBOS) at the low dose (50/(kg·BW)/d), the middle dose (200 mg/(kg·BW)/d) and the high dose (500 mg/(kg·BW)/d) partly once a day, which is also 28 days in a row. At the same time, (SBOS) mice in the drug group and (CG) mice in the positive control group were given intraabdominal injection of CTX (200 mg/kg/d).The immunosuppressive mouse model (CY) was established after 72 h in the model group and the positive control group (CG) was given intragastric administration of levamisole hydrochloric acid (LMS) for 3 days, with the data of 80ug/kg/d after injection of CTX (for actually 72 h). On the 8th, 15th and 22nd day, the number of Bifidobacterium, Lactobacillus, Enterococcus and Clostridium perfringens m in the feces of mice in each dose of drug group were determined. After the test resulted, the cellular immune function, humoral immune function, monocyte/macrophage function, NK cell activity and cytokine secretion (tumor necrosis factor-α, interferon-gamma and IL-4) were measured in immunosuppressive mice each group. The results showed that 200 mg/(kg BW) soybean oligosaccharide could significantly promote the proliferation and inhibit the increase of Enterococcus in immunosuppressive mice. The soybean oligosaccharide of 500 mg/(kg BW) could dramatically promote the proliferation of both Bifidobacillus and Lactobacillus, and also inhibit the increase of both Enterobacteriaceae and Enterococcus in immunosuppressive mice. The regulatory function of SBOS on intestinal flora was positive. Soybean oligosaccharide (500 mg/(kg BW) could significantly promote the proliferation of Bifidobacillus and Lactobacillus in immunosuppressive mice and inhibit the increase of Enterococcus and Enterococcus. The proliferation of spleen lymphocytes induced by ConA, LPS in immunosuppressive mice was dose-dependent. But it was still lower than that of the normal group (CG0) (p > 0.05). The serum hemolysin level of immunosuppressive mice was significantly increased in each dose group (p < 0.05), and the level of antibody forming cells in spleen cells of each dose group was significantly increased (P < 0.05), and the level of antibody forming cells in spleen cells of each dose group was significantly higher than that of low dose group (p < 0.005), and the level of serum hemolysin in immunosuppressive mice was significantly increased in each dose group (p < 0.05). In the detection of immune effector cell activity in immunosuppressive mice, the phagocytic function of macrophages in high dose group and the natural killing activity of spleen NK cells in high dose drug group were significantly increased, which were not significantly different from those in positive control group (P < 0.05), but the expression of TNF-α, INF-γ and IL-4 cytokines in serum was increased in a dose dependent manner (p < 0.05). In conclusion, soybean oligosaccharide can significantly increase the diversity of intestinal microecology, increase the number of intestinal beneficial bacteria, has a correlation with the proliferation of Bifidobacterium and Lactobacillus in the intestinal tract, and inhibit the proliferation of harmful bacteria. The results showed that SBOS had a direct effect on the proliferation of intestinal flora under immunosuppression. Based on the improvement of intestinal microenvironment in immunosuppressive mice by soybean oligosaccharide for 25 days, the results showed that compared with the positive control group, the nonspecific and specific immunity of immunosuppressive mice in the drug group had a regulatory effect, which improved the phagocytic function of monocytes/macrophages, developed the level of antibody forming cells, enhanced the standard of the killing activity of NK cells, and promoted the expression of cytokines as well. Compared with the model group, the transformation and proliferation of spleen lymphocytes in the high and middle dose groups were remarkably increased, but all of the indexes did not reach the level of the normal blank group. By studying the improvement of intestinal microenvironment in immunosuppressive mice, to some extent, it is concluded that the proliferation of intestinal flora can improve the immunomodulatory function of the body, but it still lowers the normal immune degree, which reflects the immunomodulatory effect of the body on the stimulation of continuous external intake. The results demonstrate that the immunomodulatory ability of immunosuppressive body was insensitive to SBOS and provided a theoretical basis for the study of health care function of intestinal microenvironment improvement when SBOS acted on abnormal immune function. The results also improved the practical application value of SBOS.     

Virulizin, a novel immunotherapy agent, activates NK cells through induction of IL-12 expression in macrophages

Virulizin, a novel biological response modifier, has demonstrated significant antitumor efficacy in a variety of human tumor xenograft models including melanoma, pancreatic cancer, breast cancer, ovarian cancer and prostate cancer. The significant role of macrophages and NK (Natural killer) cells was implicated in the antitumor mechanism of Virulizin where expansion as well as increased activity of macrophages and NK cells were observed in mice treated with Virulizin. Depletion of macrophages compromised Virulizin-induced NK1.1⁺ cell infiltration into xenografted tumors and was accompanied by reduced antitumor efficacy. In the present study, involvement of macrophages in NK cell activation was investigated further. We found that depletion of NK cells in CD-1 nude mice by anti-ASGM1 antibody significantly compromised the antitumor activity of Virulizin. Cytotoxicity of NK cells isolated from Virulizin-treated mice was enhanced against NK-sensitive YAC-1 cells and C8161 human melanoma cells, but not against NK-insensitive P815 cells. An increased level of IL-12 was observed in the serum of mice treated with Virulizin. IL-12 mRNA and protein levels were also increased in peritoneal macrophages isolated from Virulizin-treated mice. Moreover, Virulizin-induced cytotoxic activity of NK cells isolated from the spleen was abolished when an IL-12 neutralizing antibody was co-administered. In addition, depletion of macrophages in mice significantly impaired Virulizin-induced NK cell cytotoxicty. Taken together, the results suggest that Virulizin induces macrophage IL-12 production, which in turn stimulates NK cell-mediated antitumor activity.     

The role of natural killer cells and interferon in resistance to acute infection of mice with herpes simplex virus type 1

The relative roles of interferon (IFN) and natural killer (NK) cells in herpes simplex virus type 1 (HSV-1) infection of mice were examined. Adoptive transfer of adult mouse leukocytes into 4- to 6-day-old suckling mice protected the recipients from HSV-1 infection, as judged by viral titers in the spleen 2 days postinfection. Protection was mediated by several classes of leukocytes, including those depleted of NK cell activity by antibody to asialo GM1 and those depleted of macrophages by size separation. Mice receiving these leukocytes produced significantly higher levels of IFN 6 hr postinfection (early IFN) than did HSV-1-infected mice not receiving donor leukocytes. Antibody to IFN, under conditions that blocked early but not late IFN synthesis, greatly enhanced HSV-1 synthesis in mice receiving leukocytes and completely removed the protective effect mediated by leukocytes. High doses of anti-asialo GM1 blocked both NK cell activity and early IFN production and resulted in high titers of HSV-1. This effect on virus synthesis was not seen if mice were given antibody 1 day postinfection. Lower doses of anti-asialo GM1, which still depleted NK cell activity but had no effect on early IFN production, did not enhance HSV-1 synthesis. Depletion of NK cell activity with a low dose of antibody had no effect on the reduced HSV-1 synthesis resulting from prophylactic IFN treatment or on the enhanced HSV-1 synthesis resulting from antibody to IFN treatment. Thus, resistance to acute HSV-1 infection in mice correlates with early IFN production but not with NK cell activity, suggesting that NK cells are not major mediators of natural resistance in this model and that the antiviral effect of IFN is not mediated by NK cells.     

Modulation of the immune response to tumors by a novel synthetic compound,N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide (CL 259,763)

Summary CL 259,763, N-[4-[(4-fluorophenyl)sulfonyl]phenyl] acetamide, is an orally active compound capable of modifying the reactivity of certain lymphoid cell populations affected by the growth of a tumor. The compound augmented the response of lymphocytes from tumor-primed animals to syngeneic tumor cells, resulting in a marked increase in tumor cell destruction. Likewise, it enhanced macrophage inhibitory effects on the growth of tumor cells in vitro. These activated macrophages were detectable in peritoneal exudates of treated mice 4 to 12 days after receiving a single oral dose of CL 259,763, with peak activity being demonstrable by day 7. The compound also restored the alloreactivity of lymphocytes from immunodepressed mice bearing the Lieberman plasma cell tumor, possibly by interferring with suppressor cells. Macrophages and lymphocytes from treated mice released significantly more IL-1 and IL-2-like factors in culture than did the control counterparts. Sera from treated mice also possessed more colony stimulating factor than those from normal mice. Immunoadjuvant effects were evident when the compound was administered with an inactivated L1210 leukemia vaccine and it enhanced the effectiveness of cytotoxic chemotherapy when given to mice challenged with P388 murine leukemia. These immunomodulating effects of CL 259,763 may hopefully be exploited in efforts to augment the immune response of the host to a progressively growing tumor.     

The chemokine CX3CL1 regulates NK cell activity in vivo

In vitro, chemokines can both activate and induce migration of NK cells. However, little is known about how chemokines influence NK cell activity in vivo. We studied the role of CX(3)CL1 and its receptor, CX(3)CR1, in modulating NK cell activity in an established in vivo model of tumour cell clearance. Radiolabelled YAC-1 target cells intravenously injected into C57BL/6 mice rapidly localize to the lungs and are cleared by NK cells. In mice pre-treated with blocking anti-CX(3)CL1 or anti-CX(3)CR1 Ab, target cell clearance decreased by four- to fivefold (p<0.001). In vitro, we found no effect of anti-CX(3)CL1 or anti-CX(3)CR1 Ab on NK lysis of target cells. We further examined adhesion of NK cells to Py-4-1 endothelial cells. NK cell binding to activated endothelial monolayers was significantly inhibited by anti-CX(3)CR1 Ab or soluble CX(3)CL1 (p<0.001). These studies identify a critical role for CX(3)CL1 in modulating NK cell activity in vivo.     

西藏灵菇胞外多糖组分对小鼠免疫调节作用及机制的研究

摘要：【目的】研究数均分子量为0.1×105~3.0×105（组分1）及1.8×103（组分2）的西藏灵菇胞外多糖组分对正常小鼠免疫功能的影响,并探讨其影响机制。【方法】依据卫生部保健食品功能学评价程序和检验方法,灌胃给药,剂量分别120 mg/kg体重、80 mg/kg体重、40 mg/kg体重,检测脏器／体重比值、半数溶血值（HC50）、自然杀伤细胞（NK）活性、迟发型变态反应（DTH）、腹腔巨噬细胞吞噬功能。采用免疫印迹法,测定小鼠腹腔巨噬细胞中Erk蛋白及COX-2酶的表达量。【结果】组分1能够明     

Induction of activated macrophages by intraperitoneal injection of mitomylin C in mice

Summary The host cellular response to IP injection of mitomycin C was studied in C3H/HeN mice. As assessed by in vitro cytolysis assay using ¹²⁵I-iododeoxyuridine-labelled tumour target cells, mitomycin C-induced peritoneal macrophages showed the maximum tumouricidal activity 4 days after the IP injection. The tumouricidal activity was dependent on the dose of mitomycin C injected and it was detectable against syngeneic, allogeneic and xenogeneic tumour target cells. In addition, these tumouricidal macrophages were found to be augmented in functions of both incorporation of 2-deoxy-D-glucose and phagocytosis of sheep red blood cells. Among the other anti-cancer drugs, which were used at a dose of three-fifths of LD₅₀, only adriamycin (7.5 mg/kg) was capable of inducing activated macrophages as much as mitomycin C (3 mg/kg). Cyclophosphamide (225 mg/kg), methotrexate (60 mg/kg) and vincristin (1.5 mg/kg) were able to augment incorporation of 2-deoxy-D-glucose and phagocytosis of sheep red blood cells, but not tumouricidal actvity. Differential cytolysis assay was performed for two cell lines of P 388 tumour target cells, the mitomycin C-sensitive original cell line and the mitomycin C-resistant subline, demonstrating no significant difference in macro-phage-mediated tumour cell lysis between these cell lines. Based on these results, it was concluded that mitomycin C, when injected IP induced activated macrophages in the peritoneal cavity. A better understanding of the effect of anti-cancer drugs on macrophage tumouricidal activity may be useful in designing more effective local chemotherapy for malignant peritoneal effusions.     

Natural killer (NK) cell activity during lymphatic regeneration: early appearance of Thy-1+ NK cells and highly interleukin 2-(IL 2) receptive, Thy-1- cells

The appearance of natural killer (NK) cells, i.e., cells that can lyse tumor-derived target cells without intentional immunization, was studied during regeneration after a sublethal dose (300 mg/kg) of cyclophosphamide (Cy). It was found that NK activity started to increase in parallel with the number of cells in the spleen, reaching normal levels 8 to 9 days after Cy injection. The early appearing NK cells differed, however, from the NK cells of the normal spleen; all the activity was abolished by treatment with a monoclonal anti-Thy-1 antibody plus complement (C). The early regenerating population contained cells that could given rise in vitro, in the presence of interleukin 2 (IL 2), to higher amounts of NK-active cells than cells of a normal spleen. Pretreatment with anti-Thy-1 (plus C) did not inhibit the formation of these in vitro NK-active cells, indicating that they were not derived from these Thy-1+ NK cells. The NK cells formed in vitro expressed both the asialo GM1 and the Thy-1 antigens. These data suggest that i) the expression of the Thy-1 antigen on NK cells is connected to their stage of maturation or to the rate of proliferation, and ii) the precursors for the in vitro activated NK cells are not NK-active cells themselves.     

The effect of vitamin B6 deficiency on cytotoxic immune responses of T cells, antibodies, and natural killer cells, and phagocytosis by macrophages

The effect of vitamin B6 on cytotoxic immune responses of T cells, natural killer (NK) cells, cytotoxic antibody production, and macrophage phagocytosis was assessed in 5-week-old female C57B1/6 mice. Mice were fed 20% casein diets with pyridoxine (PN) added at 7, 1, 0.1, or 0 mg/kg diet, which represents 700, 100, 10, and 0% of requirement, respectively. Compared to mice fed 7 or 1 mg PN diet, animals fed 0 or 0.1 mg PN diet showed significantly reduced primary splenic and peritoneal T-cell-mediated cytotoxicity (CMC). Animals fed 0 mg PN diet also showed significantly depressed secondary T CMC of splenic and peritoneal lymphocytes against P815 tumor cells. Complement-dependent antibody-mediated cytotoxicity against P815 cells, phagocytosis of SRBC by macrophages, and native and interferon-induced NK cell activities against YAC cells were not affected by the level of vitamin B6 intake. The percentage of macrophages present in the peritoneal exudate cells was increased in animals fed the 0 mg PN diet. The immune responses were not enhanced or altered by the excess intake of vitamin B6 (7 mg PN). It appears that vitamin B6 is an essential nutrient for maintenance of normal T-cell function in vivo.     

植物乳杆菌P-8对小鼠免疫功能的调节作用研究

摘要 目的：不同类型的益生菌株免疫调节功能各异。本文旨在评价植物乳杆菌P-8（Lactobacillus plantarum P-8）对小鼠免疫功能的调控作用及机制。方法：C57BL/6J小鼠每日灌胃给予不同剂量的植物乳杆菌P-8（0. 25 mg/kg、0.5 mg/kg、1.5 mg/kg）,连续30天,记录小鼠一般情况。给药结束后处死动物,测定小鼠脏器/体重比;小鼠碳廓清实验、小鼠腹腔巨噬细胞吞噬鸡红细胞实验评价各组小鼠的单核-巨噬细胞功能;血清溶血素测定、抗体生成细胞实验评价各组小鼠的体液免疫功能;脾淋巴细胞转化实验、迟发型变态反应实验评价各组小鼠的细胞免疫功能;NK细胞的活性测定实验评价小鼠的NK细胞活性。结果：与对照组相比,低、中、高剂量组植物乳杆菌P-8对小鼠脏器/体重比值差异无统计学意义（P>0.05）;且植物乳杆菌P-8可显著提高小鼠的碳廓清能力、小鼠腹腔巨噬细胞吞噬鸡红细胞能力、半数溶血值、二硝基氟苯诱导的小鼠迟发型变态反应及NK细胞活力（P均<0.05）。结论：植物乳杆菌P-8可通过提高单核-巨噬细胞功能、体液免疫功能、细胞免疫功能及NK细胞活力增强小鼠的免疫功能。     

Effect of a glucan,sizofiran, on natural-killer activity of 5-fluorouracil-treated murine bone marrow cells

Summary The number of bone marrow cells in C3H/He mice was reduced 3–4 days after treatment with 130 mg/kg intraperitoneal 5-fluorouracil (5-FU). Higher rates of spontaneous proliferation and natural killer (NK) activity, accompanied by an increase in asialoGM1-positive cells, were observed in treated mice. When sizofiran at a dose of 200 µg/animal was intramuscularly injected after 5-FU treatment, the rates of proliferation and NK activity of bone marrow cells were higher than with 5-FU alone. The cell number was not influenced by sizofiran alone. These results indicate that all precursors of the various mature cell types (including NK cells) differentiate and regenerate rapidly to replace cells damaged by 5-FU treatment, and that sizofiran has the potential to assist this recovery. These results suggest that administration of sizofiran after chemotherapy may be useful in cancer patients.     

The role of NK cell activity in age-dependent resistance of mice to murine cytomegalovirus infection

The resistance of mice to cell culture passaged murine cytomegalovirus (CC-MCMV) infection developed with age. In parallel with this finding, augmentation of the splenic NK cell activity in older mice was always higher than that of younger mice. The splenic NK cell activity reached the maximum level at 6 day post infection (PI) in 2-4-week-old mice while in 6-8-week-old mice it peaked at 4 days PI. When the dose of CC-MCMV was increased, the NK cell activity was potentiated accordingly. However, it was decreased on the infection with increased doses of the salivary gland passaged MCMV (SG-MCMV). NK cells augmented by MCMV infection actually inhibited in vitro replication of MCMV when they were added to mouse embryonic fibroblast (MEF) monolayers infected with CC-MCMV. Splenic and peritoneal macrophages inhibited in vitro replication of MCMV, but their activities were less potent than those of NK cells.     

Leukemogenesis by methylnitrosourea in BDF1 mice. The origin of transplantable cells and the activity of the natural killer cells during the preleukemic period

BDF1 mice injected with methylnitrosourea (MNU, 50 mg/kg) developed T cell leukemias within 9-35 weeks (median induction time 18 weeks). Leukemic cells, determined by transplantation, were found 2-5 weeks before the death of the animals. Natural killer (NK) cell activity in the spleen and peritoneal exudate cells was studied using YAC-1 cells as targets. MNU-treated mice showed reduced lytic activity with or without stimulation by Corynebacterium parvum. NK activity was essentially the same in mice with and without transplantable leukemic cells. No correlation could be demonstrated between the degree of NK cell depression, as studied in the spleen after splenectomy, and the survival time of individual mice.     

In vitro modulation of mouse natural killer (NK) cell activity by the serum thymic factor (FTS)

Previous studies indicated that the serum thymic factor (FTS) could modulate in vivo the level of splenic natural killer (NK) cell activity in mice. The present report shows that such an effect is also observed after a short term in vitro incubation of the effector cells with FTS. The regulatory effects of FTS result in an increase or a decrease of the splenic NK cell cytotoxicity depending upon the age and the mouse strain. Furthermore, FTS is able to enhance the NK cell activity of thymus and bone marrow cells which are known to be weakly reactive in NK cytotoxicity. Depletion experiments demonstrated that the FTS-induced increase of NK cell activity was not mediated by Thy 1+ cells nor macrophages, thus suggesting a direct action of FTS on the effector cells. Comparative studies using other thymic hormones revealed similar patterns of reactivity. These results favor the hypothesis of a close relationship between the thymus and NK cells.     

Inhibition of CX3CL1 (fractalkine) improves experimental autoimmune myositis in SJL/J mice

Idiopathic inflammatory myopathy is a chronic inflammatory muscle disease characterized by mononuclear cell infiltration in the skeletal muscle. The infiltrated inflammatory cells express various cytokines and cytotoxic molecules. Chemokines are thought to contribute to the inflammatory cell migration into the muscle. We induced experimental autoimmune myositis (EAM) in SJL/J mice by immunization with rabbit myosin and CFA. In the affected muscles of EAM mice, CX3CL1 (fractalkine) was expressed on the infiltrated mononuclear cells and endothelial cells, and its corresponding receptor, CX3CR1, was expressed on the infiltrated CD4 and CD8 T cells and macrophages. Treatment of EAM mice with anti-CX3CL1 mAb significantly reduced the histopathological myositis score, the number of necrotic muscle fibers, and infiltration of CD4 and CD8 T cells and macrophages. Furthermore, treatment with anti-CX3CL1 mAb down-regulated the mRNA expression of TNF-alpha, IFN-gamma, and perforin in the muscles. Our results suggest that CX3CL1-CX3CR1 interaction plays an important role in inflammatory cell migration into the muscle tissue of EAM mice. The results also point to the potential therapeutic usefulness of CX3CL1 inhibition and/or blockade of CX3CL1-CX3CR1 interaction in idiopathic inflammatory myopathy.