Model for mediastinal lymph node metastasis produced by orthotopic intrapulmonary implantation of lung cancer cells in mice

This study is designed to establish a pulmonary tumor model to investigate the biology and therapy of lung cancer in mice. Current methods for forming a solitary intrapulmonary nodule and subsequent metastasis to mediastinal lymph nodes are not well defined. Lewis lung carcinoma cell (LLC) suspensions were orthotopically introduced into the lung parenchyma of C57/BL6 mice via a limited skin incision without thoracotomy followed by direct puncture through the intercostal space. The implantation process was performed within approximately 50 sec per mouse, and the operative mortality was less than 5%. Single pulmonary nodules developed at the implanted site in 93% of animals and subsequent mediastinal lymph nodes metastasis were observed in all mice that were succeeded to form a lung nodule after intrapulmonary implantation. The size of tumor nodule and the weight of mediastinal lymph node increased in a time-dependent manner. The mean survival time of mice implanted successfully with LLC cells was 21 +/- 2 days (range; 19-24 days). Histopathological analysis revealed that no metastatic tumor was detectable in the mediastinal lymph nodes on day 11, but metastatic foci at mediastinal lymph nodes were clearly observed on days 17 and 21 after implantation. Other metastases in distant organs or lymph nodes were not observed at 21 days after the implantation. Comparative studies with intrapleural and intravenous injections of LLC cells suggest that the mediastinal lymph node metastasis by intrapulmonary implantation is due to the release of tumor cells from the primary nodule, and not due to extrapulmonary leakage of cells. An intravenous administration of CDDP on day 1 after tumor implantation tended to suppress the primary tumor nodule and significantly inhibited the lymph node metastasis. Thus, a solitary pulmonary tumor nodule model with lymph node metastasis approximates clinical lung cancer, and may provide a useful basis for lung cancer research.     

Antibacterial activity of wine phenolic compounds and oenological extracts against potential respiratory pathogens

Aims: To investigate the effect of seven wine phenolic compounds and six oenological phenolic extracts on the growth of pathogenic bacteria associated with respiratory diseases (Pseudomonas aeruginosa, Staphylococcus aureus, Moraxella catarrhalis, Enterococcus faecalis, Streptococcus sp Group F, Streptococcus agalactiae and Streptococcus pneumoniae). Methods and Results: Antimicrobial activity was determined using a microdilution method and quantified as IC₅₀. Mor. catarrhalis was the most susceptible specie to phenolic compounds and extracts. Gallic acid and ethyl gallate were the compounds that showed the greatest antimicrobial activity. Regarding phenolic extracts, GSE (grape seed extract) and GSE‐O (oligomeric‐rich fraction from GSE) were the ones that displayed the strongest antimicrobial effects. Conclusions: Results highlight the antimicrobial properties of wine phenolic compounds and oenological extracts against potential respiratory pathogens. The antimicrobial activity of wine phenolic compounds was influenced by the type of phenolic compounds. Gram‐negative bacteria were more susceptible than Gram‐positive bacteria to the action of phenolic compounds and extracts; however, the effect was species‐dependent. Significance and Impact of Study: The ability to inhibit the growth of respiratory pathogenic bacteria as shown by several wine phenolic compounds and oenological extracts warrants further investigations to explore the use of grape and wine preparations in oral hygiene.     

Protective effect of Montilla-Moriles appellation red wine on oxidative stress induced by streptozotocin in the rat

This study evaluated the protective effect of Montilla-Moriles appellation red wine (Cordoba, Spain) on oxidative stress, course and intensity of symptoms in experimental diabetes induced by the injection of streptozotocin in male Wistar rats. The rats were injected with a single dose of streptozotocin (60 mg/kg i.p.) and given water and red wine separately. After 4 weeks of treatment, blood samples were obtained to determine sugar and fructosamine concentrations in blood plasma, serum insulin concentration, and percentage of glycosylated hemoglobin in blood. The kidney, liver, and pancreas were removed to determine lipid peroxidation levels, reduced glutathione content, and antioxidative enzyme activity. A significant increase of glucose concentration in urine was found in the rats after injecting the streptozotocin. The administration of red wine before streptozotocin elevated reduced glutathione content and antioxidative enzyme activity, while lowering the lipid peroxidation level. Moreover, the red wine induced decreased levels of glycemia, plasma fructosamine and percentage of glycosylated hemoglobin, while increasing levels of insulin. These data suggest that red wine has a protective effect against oxidative stress and diabetes induced by streptozotocin.     

Red wine polyphenolics suppress the secretion and the synthesis of Apo B48 from human intestinal CaCo-2 cells

Epidemiological studies suggest that the red wine consumption may reduce the risk factor of cardiovascular disease. However, the mechanisms of how the red wine phenolic components reduce the risk of cardiovascular disease is currently unknown. Our previous study demonstrated that red wine polyphenolics suppress the secretion of pro-atherogenic lipoproteins (very low density lipoproteins) from human hepatic HepG2 cells. Therefore, in this study we hypothesize that red wine polyphenolics will also attenuate the production and secretion of another pro-atherogenic lipoprotein (chylomicrons) from human intestinal CaCo-2 cells. Cultured CaCo-2 cells were incubated in the presence of dealcoholized red wine, alcoholized red wine and atorvastatin for 24 h. The apo B48 protein (marker of intestinal chylomicrons) was quantified on Western blotting and the enhanced chemiluminescence. Apo B48 levels in the cells and that secreted into the media were significantly reduced by 29% in the cells incubated with dealcoholized red wine compared with control cells. Also the similar effect was shown in the cells incubated with alcoholized red wine. The cells incubated with atorvastatin shown the significant reduction of apo B48 production compared to control cells. Collectively, this study suggests that red wine polyphenolics down regulate the production of chylomicron in intestinal CaCo-2 cells.     

Resveratrol,a red wine constituent polyphenol,prevents superoxide-dependent inflammatory responses induced by ischemia/reperfusion,platelet-activating factor,or oxidants

Moderate consumption of red wine has been shown to exert cardioprotection against ischemia/reperfusion. Because oxidant-dependent leukocyte infiltration plays a critical role in ischemia/reperfusion-induced tissue injury, we hypothesized that resveratrol, a red wine constituent polyphenol would attenuate postischemic leukocyte recruitment and subsequent endothelial dysfunction. Intravital microscopic approaches were used to quantify leukocyte/endothelial cell interactions and venular protein leakage in rat mesenteries exposed to either 20 min ischemia and 60 min reperfusion (I/R), oxidants generated by the reaction of hypoxanthine and xanthine oxidase (HX/XO), platelet-activating factor (PAF), or leukotriene B4 (LTB4). I/R or HX/HX produced marked increases in the number of adherent (LA) and emigrated (LE) leukocytes, which were associated with significant increases in venular albumin leakage (VAL). Intravenous administration of resveratrol or superoxide dismutase (SOD) attenuated these increases in LA, LE, and VAL. Superfusion of the mesentery with PAF or LTB4 also markedly increased LA, LE, and VAL. While resveratrol attenuated the proinflammatory effects of PAF, LTB4-induced changes were not affected by resveratrol. Resveratrol prevents leukocyte recruitment and endothelial barrier disruption induced by a number of superoxide-dependent proinflammatory stimuli, including I/R, HX/XO, or PAF. These salutary effects appear to be related to the antioxidant properties of resveratrol and contribute to the cardioprotective actions associated with consumption of red wine.     

Resveratrol improves cognitive function in mice by increasing production of insulin-like growth factor-I in the hippocampus

We examined whether resveratrol increases insulin-like growth factor-I (IGF-I) production in the hippocampus by stimulating sensory neurons in the gastrointestinal tract, thereby improving cognitive function in mice. Resveratrol increased calcitonin gene-related peptide (CGRP) release from dorsal root ganglion (DRG) neurons isolated from wild-type (WT) mice. Increases in tissue levels of CGRP, IGF-I, and IGF-I mRNA and immunohistochemical expression of IGF-I were observed in the hippocampus at 3 weeks after oral administration of resveratrol in WT mice. Significant enhancement of angiogenesis and neurogenesis was observed in the dentate gyrus of the hippocampus in these animals (P<.01). Improvement of spatial learning in the Morris water maze was observed in WT mice after administration of resveratrol. None of the effects of resveratrol observed in WT mice were seen after resveratrol administration in CGRP-knockout (CGRP^−/−) mice. Although red wine containing 20 mg/L of resveratrol produced effects similar to those of resveratrol administrationl in WT mice, neither red wine containing 3.1 mg/L of resveratrol nor white wine exhibited such effects in WT mice. Resveratrol was undetectable in the hippocampus of WT mice administered resveratrol and red wine containing 20 mg/L of resveratrol. These observations strongly suggest that resveratrol increases hippocampal IGF-I production via sensory neuron stimulation in the gastrointestinal tract, thereby improving cognitive function in mice.     

Influence of several Styrian wines on bovine coronary artery contractions induced by endogenous agents

In the current study, seven Styrian white wine varieties, as well as their corresponding grape skin extracts (GSE), were tested for possible antagonistic effects on several endogenous vasoconstrictors known to be involved in the pathogenesis of cardiovascular diseases via tissue contraction experiments. Results were compared to those of Zweigelt, the most cultivated Styrian red wine. Bovine coronary artery strips were attached to a force transducer connected to a bridge amplifier, and isometric force was recorded on a multipen recorder. Preincubation of the vessels with the dealcoholized wines (DAW; 330 microl/ml) inhibited the constrictions to histamine and serotonin (5-HT) NO-dependently in the range of 5-80% and 30-90%, respectively (Zweigelt 47% and 90%, respectively). The corresponding GSE (20 mg/ml) inhibited the coronary constrictions to histamine in the range of 40% to 80% (Zweigelt 80%). Additionally, all DAW antagonized the contractile responses to the thromboxane-mimetic U46619 and the isoprostane 8-iso-PGF2alpha, indicating a nonspecific inhibition. To characterize the vasoactive component(s), the Traminer GSE was separated representatively using ultrafiltration, solid phase extraction (SPE) on Isolute C18(EC), and Isolute SCX-2, as well as column chromatography (CC) on polyamide. The resulting fractions were subsequently bioassayed for vasorelaxing activity. Preliminary results refer to a very hydrophilic, nonpolyphenolic basic compound with a MW<1000 Da. Our findings demonstrate that certain Styrian wines have remarkable antagonistic effects on several endogenous agonists in vitro, and that also nonpolyphenolic components in grapes may contribute to cardiovascular protection. Further separation steps as well as phytochemical and pharmacological investigations are in progress.     

Effect of red wine on oxidative stress and hypercholesterolemia induced by feeding a high-cholesterol diet in rat

The effect of red wine on oxidative stress and hypercholesterolemia induced by feeding a high-cholesterol diet (supplemented with 1.65% of cholesterol (w/w) for 4 weeks) to female Wistar rats was examined. When red wine was simultaneously supplemented to high-cholesterol diet, total cholesterol, triglycerides, atherogenic index and lipid peroxidation products significantly decreased compared with the high-cholesterol diet alone, while GSH content and antioxidative enzymes activities were enhanced. In the hypercholesterolemic rat the excretion of fecal bile acids, as well as their plasma and hepatic concentrations were increased significantly. Administration of red wine enhanced these values, indicating an increase in the cholesterol degradation. These results suggest that red wine may have a protective effect against oxidative stress, hypercholesterolemia and atherogenic index induced by high-cholesterol diet.     

Enhancement of transglutaminase activity and polyamine depletion in B16-F10 melanoma cells by flavonoids naringenin and hesperitin correlate to reduction of the <Emphasis Type="Italic">in vivo</Emphasis> metastatic potential

Summary. The in vitro and in vivo effects of two flavonons, naringenin (NG) and hesperitin (HP) on the proliferation rate of highly metastatic murine B16-F10 melanoma cell were investigated. NG or HP treatment of melanoma cells produced a remarkable reduction of cell proliferation, paralleled with both the lowering of the intracellular levels of polyamine, spermidine and spermine and the enhancement of transglutaminase (TGase, EC 2.3.2.13) activity. Orally administered NG or HP in C57BL6/N mice inoculated with B16-F10 cells affected the pulmonary invasion of melanoma cells in an in vivo metastatic assay. The number of lung metastases detected by a computerized image analyzer was reduced, compared to untreated animals, by about 69% in NG-treated mice and by about 36% in HP-treated mice. Survival studies showed that 50% of the NG-treated animals died 38 ± 3.1 days after tumor cell injection (control group: 18 ± 1.5 days) and HP-treated mice died 27 ± 2.3 days after cell inoculation. Taken together, these findings provide further evidences for the potential anticancer properties of dietary flavonoids as chemopreventive agents against malignant melanoma.     

Modulation of cytochrome P450 activity in the kidney of rats following long-term red wine exposure

Cytochrome P450 (CYP)-dependent oxidation of lauric acid, p-nitrophenol and ethanol by microsomal fractions of kidney were studied in control rats and in animals given either ethanol, red wine, or alcohol-free red wine for 10 weeks. Ethanol increased the total CYP content and specifically CYP 2E1, as well as p-nitrophenol and ethanol oxidation. The effects of ethanol treatment on the content and activity of CYP 2E1 were attenuated when red wine was administered, while the alcohol-free red wine values were similar to those of the control group. Although lauric acid hydroxylation was decreased by red wine treatment, the content of CYP 4A1 was not influenced by drinking fluids. We conclude that red wine administration attenuates the ethanol-induced enhancement of microsomal activities dependent on CYP 2E1 of rat kidney. Our results suggest that the non-alcoholic constituents of red wine could account for this modulation.     

Pharmacological analysis of wine-stimulated gastric acid secretion in dogs

Wine apparently stimulates gastric acid secretion both in man and animals, yet the underlying mechanism remains unclear. The present study was attempted to clarify the pharmacological properties involved in gastric acid secretion stimulated by wine in beagle dogs. Commercially available red or white wine, 14% ethanol, or 10% peptone meal was intragastrically administered to dogs with vagally denervated Heidenhain pouches. Gastric acid secretion was stimulated by both red and white wines (25-50 ml) for 45-60 min. While S-0509 only tended to inhibit wine-stimulated gastric acid secretion, both atropine and famotidine significantly inhibited wine-stimulated gastric acid secretion. Plasma gastrin level was not significantly increased by administration of red and white wines. Administration of 14% ethanol also stimulated gastric acid secretion, but the effect was about half of that of wine. Combined administration of wine and peptone resulted in a biphasic stimulation of gastric acid secretion. S-0509, atropine and famotidine significantly inhibited wine+peptone meal stimulation, yet the order of inhibition of cumulative acid secretion was in the order, famotidine>atropine>S-0509. It was concluded that wine stimulated gastric acid secretion in denervated dogs via acethylcholine- and histamine-dependent mechanisms, but nearly independent from the intervention of gastrin.     

An N-glycan structure correlates with pulmonary metastatic ability of cancer cells

N-Glycan structures on the surface of cancer cells have diverse structures and play significant roles in metastatic process. However, little is known about their roles in organ-selective metastasis. Our study revealed that an alpha1,6-fucosylated biantennary N-glycan structure designated A2G2F is characteristic of lungs, with far more abundant expression in normal human and murine lungs than in other organs. In this study, we further examined the role of A2G2F in pulmonary metastasis. We stained metastatic cancers by alpha1,6-fucose-specific Lens culinaris agglutinin lectin and revealed that pulmonary metastatic nodules more abundantly expressed alpha1,6-fucosylated N-glycans than hepatic metastatic nodules from common primary cancers. The most specific alpha1,6-fucosylated N-glycan structure in pulmonary metastatic cancer was identified to be A2G2F. Using a B16 melanoma cell metastasis model, we showed that A2G2F-rich B16 cells formed more pulmonary metastatic nodules than A2G2F-poor cells. Our results suggest that A2G2F plays a critical role in pulmonary metastasis.     

Modulation of rat liver cytochrome P450 activity by prolonged red wine consumption

Cytochrome P450-dependent oxidation of lauric acid, p-nitrophenol and ethanol by liver microsomal fractions were studied in control rats and in animals given either ethanol, red wine, or alcohol-free red wine for 10 weeks. Ethanol increased the total cytochrome P450 and the isoenzyme 2E1 content, as well as the p-nitrophenol hydroxylation and ethanol oxidation. These effects of ethanol treatment were attenuated by red wine administration. Red wine increased the total antioxidant capacity of plasma, whereas the alcohol-free red wine decreased the cytochrome P450 content and decreased the oxidation of lauric acid, p-nitrophenol and ethanol to values lower than control. It is concluded that red wine administration attenuates the ethanol-induced enhancement in liver microsomal parameters dependent on cytochrome P450 2E1 activity, an affect that seems to be accomplished by the non-alcoholic constituents of red wine known to have antioxidant properties.     

Comparison of Immunity in Mice Cured of Primary/Metastatic Growth of EMT6 or 4THM Breast Cancer by Chemotherapy or Immunotherapy

Purpose

We have compared cure from local/metastatic tumor growth in BALB/c mice receiving EMT6 or the poorly immunogenic, highly metastatic 4THM, breast cancer cells following manipulation of immunosuppressive CD200:CD200R interactions or conventional chemotherapy.

Methods

We reported previously that EMT6 tumors are cured in CD200R1KO mice following surgical resection and immunization with irradiated EMT6 cells and CpG oligodeoxynucleotide (CpG), while wild-type (WT) animals developed pulmonary and liver metastases within 30 days of surgery. We report growth and metastasis of both EMT6 and a highly metastatic 4THM tumor in WT mice receiving iv infusions of Fab anti-CD200R1 along with CpG/tumor cell immunization. Metastasis was followed both macroscopically (lung/liver nodules) and microscopically by cloning tumor cells at limiting dilution in vitro from draining lymph nodes (DLN) harvested at surgery. We compared these results with local/metastatic tumor growth in mice receiving 4 courses of combination treatment with anti-VEGF and paclitaxel.

Results

In WT mice receiving Fab anti-CD200R, no tumor cells are detectable following immunotherapy, and CD4+ cells produced increased TNFα/IL-2/IFNγ on stimulation with EMT6 in vitro. No long-term cure was seen following surgery/immunotherapy of 4THM, with both microscopic (tumors in DLN at limiting dilution) and macroscopic metastases present within 14 d of surgery. Chemotherapy attenuated growth/metastases in 4THM tumor-bearers and produced a decline in lung/liver metastases, with no detectable DLN metastases in EMT6 tumor-bearing mice-these latter mice nevertheless showed no significantly increased cytokine production after restimulation with EMT6 in vitro. EMT6 mice receiving immunotherapy were resistant to subsequent re-challenge with EMT6 tumor cells, but not those receiving curative chemotherapy. Anti-CD4 treatment caused tumor recurrence after immunotherapy, but produced no apparent effect in either EMT6 or 4THM tumor bearers after chemotherapy treatment.

Conclusion

Immunotherapy, but not chemotherapy, enhances CD4⁺ immunity and affords long-term control of breast cancer growth and resistance to new tumor foci.     

Development of a bioassay for the antitumor activity of biological response modifiers of the reticuloendothelial stimulant class

Summary Following intravenous administration of various doses of DiLuzio glucan, Wellcome C. parvum, or BCG, the increase in clearance of intravenous ¹²⁵IUdR-radiolabeled B16 tumor cells from the lung correlated with a subsequent reduction in the outgrowth of pulmonary tumor nodules. The ranges of values for tumor cell clearance were very much narrower for most groups of animals than the ranges obtained for the number of pulmonary tumor nodules in similar groups, allowing 2–3 times the definition of data with the former method.     

Red wine polyphenols, in the absence of alcohol, reduce lipid peroxidative stress in smoking subjects

Phenolic compounds in red wine can exert antioxidant effects on in vitro lipoprotein oxidation. This has led to speculation that red wine consumption mediates unique anti-atherosclerotic effects compared to other alcoholic beverages. However, studies assessing the effects of red wine consumption on lipoprotein oxidation ex vivo have not been conclusive. The recent identification of the F2-isoprostanes as oxidative products of arachidonic acid has provided a reliable measure of in vivo lipid peroxidation. This randomized trial investigated changes in plasma and urinary F2-isoprostane concentrations following red wine, white wine, or dealcoholized red wine consumption in humans. Eighteen male smokers consumed, in random order, red wine, white wine, or dealcoholized red wine, for two weeks with one week washout between beverages. Plasma and urinary F2-isoprostane concentrations were measured before and after each beverage. Serum gamma-glutamyl transpeptidase (gamma-GT) and urinary 4-O -methylgallic acid were measured as markers of alcohol consumption and phenolic acid absorption, respectively. Plasma F2-isoprostanes (p < .05) decreased significantly with dealcoholized red wine but not with the alcohol-containing beverages. Urinary excretion of F2-isoprostanes showed a similar trend. gamma-GT decreased significantly with dealcoholized red wine and increased with both alcohol-containing beverages (p < .01). Urinary excretion of 4-O-methylgallic acid increased significantly (p < .001) in the 24 h urine samples following red wine or dealcoholized red wine ingestion, but not with white wine. Serum urate increased and beta-carotene decreased with both alcoholic beverages relative to dealcoholized red wine. There was no change in the antioxidants alpha- and gamma-tocopherol or vitamin C with any of the beverages. The results suggest that polyphenols in dealcoholized red wine can reduce in vivo lipid peroxidation as measured by F2-isoprostanes in smoking subjects. However, no reduction in lipid peroxidation was observed following red or white wine consumption, suggesting that any protective effects of wine drinking on cardiovascular disease are unlikely to be related to inhibition of lipid oxidation.     

Influence of different storage methods on the predatory capacity of the fungi Arthrobotrys robusta and Monacrosporium thaumasium after passage through the bovine gastrointestinal tract

The biological control of helminth parasites of bovines by nematophagous fungi is an alternative to the use of drugs with the principal objective of reducing the source of infection available on pastureland. The maintenance of predatory activity of the fungal isolates is one of the basic prerequisites to ensure the success of this form of control. In this study behaviour of the isolates I31 of Arthrobotrys robusta and NF34a of Monacrosporium thaumasium was investigated following three storage methods: stored at 4 °C, cryopreserved with or without cryoprotectants or preserved in silica gel. All samples were subsequently passed through the gastrointestinal tract of calves. The latter involved the administration of 20 g of mycelia to the animals. This quantity was sufficient to recover fungal material from the faeces. The peak reduction in the number of infective larvae in the faeces occurred 24 h after administration of the samples (P < 0.05). The storage at 4 °C was the treatment that produced the greatest reduction in larvae for NF34a (81.3%) and I31 (65.1%) isolates. Nf34a isolate was responsible for the highest percentage reduction of larval helminth populations (P < 0.05). Cryopreservation appears to be an efficient method of preserving isolates, although diminished predatory capacity compared to storage at 4 °C was seen only for isolate NF34a (73.2%). Cryopreservation did not interfere in predatory activity of I31 isolate (P < 0.05). Maintenance of isolates in silica gel showed the lowest reduction throughout the experiment (P < 0.05).     

In vitro characteristics of metastatic variant subclones of restricted genetic origin

We have studied several metastatic variant cell lines derived from a common clonal origin and their transformed and untransformed parental cell lines. A number of in vitro characteristics were examined for each tumor line and these properties were correlated with the ability of the tumor cells to form pulmonary nodules in an experimental metastasis assay. Direct correlations with metastatic behavior in the lung colony assay were found to exist with the amount of cell-bound Concanavalin A and the procoagulant activities of cell lysates. In vitro parameters that did not correlate with the metastatic phenotype were: population doubling times in culture, saturation density achieved in culture, the number of colony-forming cells shed from confluent cultures, rates of cellular attachment to homotypic or heterotypic cell monolayers, plasminogen-activator production and procoagulant activity produced in serum-free conditioned medium.     

Inhibition of human LDL lipid peroxidation by phenol-rich beverages and their impact on plasma total antioxidant capacity in humans

Mounting evidence shows that phenol-rich beverages exert strong antioxidant activity. However, in vivo evidence has produced conflicting results. In the present study, we studied the impact of the ingestion of 300 mL of black and green tea, alcohol-free red wine, alcohol-free white wine, or water on plasma total antioxidant capacity in five healthy volunteers. Red wine has the highest content of phenolics (3.63 +/- 0.48 g QE/L), followed by green tea (2.82 +/- 0.07 g QE/L), black tea (1.37 +/- 0.15 g QE/L), and white wine (0.31 +/- 0.01 g QE/L). Plasma total antioxidant capacity values of subjects who drank green tea rose at 30 min (P < 0.05). After black tea and red wine ingestion, the peaks were at 50 min (P < 0.05 and P < 0.01, respectively). No changes were observed in the control and white wine groups. Red wine and green tea were the most efficient in protecting low density lipoprotein from oxidation driven by peroxyl and ferril radicals, respectively. Phenol-rich beverages are a natural source of antioxidants; however, the phenolic content alone cannot be considered an index of their in vivo antioxidant activity.     

Immunologic enhancement of experimental metastasis in the rat

Summary Using a series of immunologically cross-reactive metastatic tumor variants, we demonstrate that serum from animals bearing pulmonary tumor colonies possesses enhancing properties in the experimental metastasis (lung colony) assay. Enhancement is produced by chronic serum administration and promotes the growth of tumor cells arrested in the lungs which would not otherwise proliferate to form grossly detectable lung nodules. Tumor-bearer serum from animals with lung colonies derived from the most highly metastatic variant examined is shown to possess enhancing properties in both BD-IX(H-1^d) and BD-IV(H-1^d) rat strains, while tumor-bearer serum from animals with lung colonies derived from the less metastatic parent tumor cell line possesses enhancing properties in the BD-IX rat strain only. Removal of immunoglobulin from enhancing serum by affinity column chromatography simultaneously removes the enhancing factor(s), and enhancing activity correlates with the presence of increased levels of Clq-binding immune complexes in the serum. Serum levels of immune complexes are shown to be more elevated in serum from animals bearing lung colonies derived from the most highly metastatic variant. The enhancing moieties are shown to bind to concanavalin A, but not to staphylococcal protein A, and the active fraction elutes from concanavalin A-Sepharose with -methyl-mannoside. Consideration of immunoprecipitation studies on whole and fractionated enhancing sera, along with studies on affinity purified isotype fractions reveals that the activity resides with antibodies of IgG_2b subclass. Abbreviations used: NK, natural killer cell; CIC, circulating immune complex; RhC, rheumatoid-Clq protein complex; Ig, immunoglobulin