Role of natural killer cells in the destruction of circulating tumor emboli

Establishment of a murine model for metastasis of cytokine-producing tumor to the brain

The A375 cell line, derived from human malignant melanoma, has characteristics of interleukin-6 (IL-6) production. By using this cell line, we have investigated a murine metastasis model of IL-6-producing tumors to the brain by injecting A375 cells directly into the left cardiac ventricle. Nude mice were anesthetized with intraperitoneal injection of pentobarbital sodium. Next, A375 cells suspended in phosphate-buffered saline (PBS) were injected into the left cardiac ventricle of mice. An intracardiac injection of 10(5) cells developed tumor colonies in the brain after 4 to 6 weeks. Metastatic cells were found in every lobe of the brain. An immunocytochemical study revealed IL-6 production by A375 cells at the metastatic sites in the brain. By the transfection of genes encoding proteins into A375 cells, a novel model of protein expression in the brain in vivo could be constructed. Our system does not require great skill. Our experimental model will facilitate future studies of the local effects of proteins in the brain.

The effects of general anesthesia and surgery on basal and interferon stimulated natural killer cell activity of humans

Natural killer (NK) cells can lyse certain tumor cells as well as virally infected cells without prior sensitization. Animal studies have shown that general anesthesia (GA) alone or GA followed by surgery decreases both basal NK cytotoxicity and enhancement of NK activity by interferon (IFN). The purpose of this study was to determine whether similar inhibition of NK activity by anesthesia and surgery occurs in humans. Venous blood was drawn 1 h before and 20-24 h after surgery under isoflurane/N2O anesthesia. Peripheral blood mononuclear cells (PBMC) were assayed for basal and IFN-alpha-stimulated NK cytotoxicity using a chromium release assay with K562 cells as targets. Flow cytometry was used to enumerate NK, T-helper, and T-cytotoxic/suppressor cell populations in each sample. Basal NK activity was significantly depressed after GA and GA and surgery. Although the postoperative IFN treatment increased NK activity to the preoperative basal level, the level achieved was significantly lower than the level observed after IFN stimulation of PBMC as evaluated preoperatively. This decreased activity does not seem to be the result of a decrease in the percentage of circulating NK cells. The decrease in NK activity after anesthesia and surgery may lead to increased susceptibility to infection and/or tumor dissemination and thus needs to be explored.

IMPLICATIONS

Natural killer cells can kill cancer cells and virally infected cells. This study shows that surgery with general anesthesia leads to decreased natural killer cell activity as assessed int he laboratory. This decreased natural killer cell activity may lead to infection or tumor dissemination. NK activity can be restored to presurgery levels by treating isolated NK cells with interferon-alpha.

Altered Tumor Growth and Metastasis of a T-Cell Lymphoma in Timp-1 Transgenic Mice

The concept of tumor suppression by tissue inhibitor of metalloproteinases (TIMPs) has evolved primarily from studies of genetically modulated tumor cells. The next step is to focus on the host and assess the protective potential of host TIMP-1 on primary tumor growth and metastasis. We generated two transgenic mouse lines with altered Timp-1 expression in skin and liver: one overexpressed Timp-1 (Timp-1high), and the other had antisense RNA–mediated Timp-1 reduction (Timp-1low). ESbL-lacZ T-lymphoma cells provided the tumor challenge, as they form primary tumors upon intradermal injection with spontaneous metastasis to liver. Metastases were examined in X-Gal–stained whole-organ mounts. Timp-1 overexpression inhibited intradermal tumor growth and spontaneous metastasis, leading to prolonged survival of the mice. The opposite effects occurred in Timp-1low mice, leading to shorter host survival. Experimental metastasis assays showed that Timp-1–compromised livers in Timp-1low mice showed at least a doubling of metastatic foci and numerous additional micrometastases, indicative of increased host susceptibility. However, Timp-1high mouse livers showed an unaltered metastatic load in the experimental metastasis assay. In conclusion, these data demonstrate that Timp-1 levels within a tissue predetermine the development and progression of T-cell lymphoma.

Flow cytometry analysis of peripheral blood lymphocytes in patients with choroidal melanoma

PURPOSE

To evaluate peripheral blood lymphocyte subpopulations in patients with choroidal melanoma.

METHODS

In this prospective study, peripheral blood lymphocytes of 226 patients afflicted with choroidal melanoma were analyzed by flow cytometry and compared with those of 49 age-matched and gender-matched control subjects. Subpopulations of peripheral blood lymphocytes were further identified by monoclonal antibodies specific to cell-surface markers. Statistical analysis was performed by a Student t test.

RESULTS

There was no overall difference between the patients with choroidal melanoma and the control subjects with regard to peripheral blood lymphocyte subpopulations. However, when the patients were divided into subgroups based on their clinical characteristics, differences in natural killer (NK) cell population and activated T cells were noted in two subgroups. Patients with ciliary body involvement showed a statistically significant reduction in NK cells (194 +/- 101 vs 260 +/- 178 per mm3; P = .01). The number of activated T cells in this subgroup of patients was increased but not statistically significantly (7.32 +/- 4.79 vs 6.09 +/- 4.34 per mm3; P = .08). In patients with extrascleral extension, a statistically significant increase in activated T cells was noted (9.84 +/- 7.41 vs 6.25 +/- 4.3 per mm3; P = .02). The NK cells in this subgroup of patients were also reduced, but the reduction did not achieve statistical significance (178 +/- 123 vs 248 +/- 167 per mm3; P = .24).

CONCLUSIONS

We noted statistically significant differences in peripheral blood lymphocytes in two subgroups of patients with clinically less favorable choroidal melanoma.

Increased surgery-induced metastasis and suppressed natural killer cell activity during proestrus/estrus in rats

We have previously reported sex- and estrous-related differences in host resistance to the metastatic development of a mammary adenocarcinoma cell line, MADB106, in the Fischer 344 (F344) rat. In other studies, we found that surgery suppressed natural killer (NK) cell activity and increased the NK-sensitive metastatic development of MADB106 tumor cells. The current study was designed to explore whether sex or estrous phase at the time of surgery impacts the degree of such deleterious effects of surgery. Such estrous effects could be related to an ongoing clinical debate regarding the importance of the timing of breast cancer surgery with the menstrual cycle in premenopausal women. Mature F344 males and cycling females underwent either experimental laparotomy with halothane anesthesia, halothane anesthesia alone, or were untreated. Five hours after surgery, animals either were injected with radiolabeled MADB106 tumor cells and assessed for lung tumor cell retention 12 hours later, or underwent blood withdrawal for in vitro assessment of NK cell activity. MADB106 tumor cells metastasize only to the lungs, and lung tumor cell retention is: a) an early indicator of the number of metastases that would develop weeks later, and b) highly sensitive to in vivo levels of NK activity. This mammary adenocarcinoma cell line is syngeneic to the inbred F344 strain of rats used in our studies, thus constituting a model for breast cancer metastasis. The results indicated that sex, estrous phase, and surgery interacted in their effects on NK cell activity and tumor metastasis. MADB106 lung tumor cell retention was increased by surgery in both sexes (2- to 3-fold) compared to the anesthesia only and control groups. This increase, however, was significantly greater in proestrus/estrus (P/E) females than in metestrus/diestrus (M/D) females. Among the control animals, females in P/E exhibited significantly less NK cytotoxic activity compared to the males, and the NK activity exhibited by females in M/D was between these two groups. Surgery suppressed NK cytotoxic activity to a similar level in all groups. Possible implications of these findings for the surgical care of women with breast cancer are discussed.

Lymphocytic subpopulation changes after open and laparoscopic cholecystectomy: a prospective and comparative study on 38 patients

Up to now it has been unclear whether laparoscopic surgery has fewer immunosuppressive effects than traditional laparotomic procedures. In a series of 38 patients affected by symptomatic gallstone disease and operated on either by laparoscopy (group 1) or by traditional open surgery (group 2), we determined the postoperative changes in lymphocyte subpopulations up to postoperative day (POD) 30. We collected 15 ml of venous blood from all patients in both groups on the day before surgery and on POD 1, 7, 15, and 30. A control group (group 3) comprised 56 healthy volunteers; the control group was used only to ensure that baseline values were totally comparable with a normal population; only one blood sample was obtained from the subjects in group 3. Patients undergoing open cholecystectomy had a significant decrease in total lymphocyte count on POD 1. Basal levels of lymphocyte subpopulations did not differ significantly in the study and control groups. No differences were found in the preoperative lymphocyte cell counts in the two groups who underwent cholecystectomy. Pan-T cells (CD3) showed a statistically significant marked reduction throughout the observation period. The counts of helper (CD4), suppressor (CD8), and natural killer NK (CD16) T cells were reduced on POD 1; the NK cell (CD16) count remained low until POD 30, B lymphocytes showed no postoperative reduction. In patients who underwent laparoscopic cholecystectomy, a significant postoperative decrease in total lymphocyte count, and in CD3, CD4, and CD8 subpopulations was observed on day 1 only. There was no reduction in CD16 and CD19 subpopulations. A comparative statistical analysis of lymphocyte subpopulations in the two groups was carried out: In the open cholecystectomy group, compared with the laparoscopy group, CD3, CD4, CD8, and CD16 lymphocyte subpopulations showed marked reductions at different time points. In particular, statistically significant differences were found in CD3 levels from POD 1 through POD 30, in CD4 from day 1 through day 7, and in CD8 and CD16 only on day 1.

Lymphoma in patients with rheumatoid arthritis: association with the disease state or methotrexate treatment

Although long-term clinical studies have shown no excessive risk of lymphoma in rheumatoid arthritis (RA) patients treated with methotrexate (MTX), an increasing number of reports of this association continue to appear. We describe two cases, review the cases in the world's literature, and summarize their important characteristics. Possible oncogenic mechanisms are discussed. Most lymphoproliferation cases presented here have features of immunosuppression-associated lymphoma. The immunosuppressed state is attributable to a combination of factors, such as RA itself and the actions of MTX. The risk factors for RA patients to develop lymphoma while on MTX include severe disease, intense immunosuppression, genetic predisposition, and an increased frequency of latent infection with prooncogenic viruses such as Epstein-Barr virus (EBV). The spontaneous remission of lymphomas in eight RA patients after MTX was stopped highlights the likely causative role of the drug in the development of these malignancies. If the clinical situation permits, a period of observation for spontaneous remission after MTX is stopped is advisable. The physicians caring for RA patients on MTX should maintain a high surveillance for signs and symptoms suggestive of lymphoma.

Experimental pulmonary sarcoma metastases in athymic nude mice

BACKGROUND

Pulmonary metastases remain a challenging therapeutic problem in the treatment of patients with soft tissue sarcomas. A pulmonary sarcoma metastases animal model might facilitate studying the biology of metastases, diagnosis, and treatment modalities of this disease. Intravenous injection of human tumor cells into nude mice has been reported using human melanoma and colorectal carcinoma to produce pulmonary metastases. Human fibrosarcoma cells were intravenously administered to athymic nude mice to simulate clinical pulmonary metastases.

METHODS

HT-1080 human sarcoma cells derived from a poorly differentiated fibrosarcoma were used to prepare inoculant at a concentration of 5 x 10(6) cells per ml. Male athymic nude mice were injected subcutaneously with 1 x 10(6) cells in the right hind flank and sacrificed when the tumors were 1-2 cm in diameter. Age- and weight-matched athymic nude mice were intravenously injected through tail veins with 10(4), 10(5), and 10(6) cells. The mice were sacrificed at 7, 14, and 21 days after intravenous injection of the tumor cells. Tissues were histologically examined for pulmonary metastases.

RESULTS

Neither gross nor microscopic spontaneous metastases were found in any of the animals that received subcutaneous xenografts, and no pulmonary metastases were identified in mice intravenously injected with < 10(5). All mice inoculated with 10(6) cells developed tumor colonies in the lungs, which were microscopically evident as early as day 7. No metastases were found in the liver, spleen, heart, or other tissues. In a second experiment, HT-1080 cells were injected at 10(6); all animals developed lung metastases and died of lung tumor involvement, with an average survival of 35 days.

CONCLUSIONS

These experiments identify a sarcoma animal pulmonary metastases model that is readily available, relatively inexpensive, easily utilized, and reproducible.

The immune-suppressive nature of pain

OBJECTIVES

To review evidence that the immune system plays a role in controlling the spread of cancer and findings that perioperative pain relief improves immune status and health outcomes.

DATA SOURCES

Research studies and review articles pertaining to immunity, immune function, stress, and immune-suppressive nature of pain.

CONCLUSIONS

Pain not only results in suffering but is a pathogen itself, capable of facilitating the progression of metastatic disease. Adequate pain relief decreases these risks.

IMPLICATIONS FOR NURSING PRACTICE

Adequate pain relief is not only a primary concern in caring for individuals in pain but may be a matter of physiologic necessity as further studies reveal the immune-suppressive nature of pain.

Methylcholanthrene-induced sarcomas in nude mice have short induction times and relatively low levels of surface MHC class I expression

In order to study the role of the T-cell-mediated immune defense in tumor development, a total of 93 sarcomas were induced using different doses (8 micrograms (0.1%), 40 micrograms (0.5%) and 400 micrograms (5%)) of 3-methylcholanthrene in athymic nude Balb/c mice and phenotypically normal immunocompetent Balb/c mice. A shorter tumor induction time and a higher tumor incidence after treatment with low doses of methylcholanthrene were seen in nude mice than in immunocompetent mice, indicating that they have a lower resistance to the carcinogen. Contrary to expectations we found that the MHC class I expression of tumors from nude mice was lower than that of tumors from normal mice. Higher surface expression of MHC class I was demonstrated on high dose tumors from normal mice than on low dose tumors from normal mice. The cellular composition of the individual tumors raised in nude mice was more heterogeneous with respect to MHC class I expression. Since the mice differ genetically only with respect to the nu gene, these results indicate that a lack of T-cell-mediated defense mechanisms may confer upon the bearer a lower resistance to 3-methylcholanthrene and a different MHC profile of the ensuing tumor.

Predominant role of alpha 4-integrins for distinct steps of lymphoma metastasis

To analyze the role of alpha4-integrins in lymphoma metastasis, sublines of the T-cell lymphoma LB were generated by retrovirus-mediated gene transfer that differ exclusively in the expression of alpha4-integrins. Using LB-alpha4 and control LB-NTK cells, we demonstrate that expression of alpha4-integrins strongly suppresses metastasis formation of LB lymphoma cells in secondary lymphoid organs such as spleen, mesenteric and peripheral lymph nodes, or Peyer's patches after i.v. injection into syngeneic BALB/c mice. Moreover, alpha4-integrin expression inhibited development of metastatic tumors in liver, lung, and kidney. Expansion of LB lymphoma cells in bone marrow was not affected by alpha4-integrin expression. In vivo migration assays using 51Cr-labeled lymphoma cells demonstrated that low-metastatic LB-alpha4 cells accumulated with the same efficiency as high-metastatic LB-NTK cells in all target organs examined and were even enriched in mucosal lymphoid organs. Collectively, these results indicate that alpha4-integrins inhibit metastasis formation of lymphoma cells at a stage subsequent to the invasion of target organs.

Molecular mechanisms of lymphocyte-mediated cytotoxicity and their role in immunological protection and pathogenesis in vivo

Studies with perforin-deficient mice have demonstrated that two independent mechanisms account for T cell-mediated cytotoxicity: A main pathway is mediated by the secretion of the pore-forming protein perforin by the cytotoxic T cell, whereas an alternative nonsecretory pathway relies on the interaction of the Fas ligand that is upregulated during T cell activation with the apoptosis-inducing Fas molecule on the target cell. NK cells use the former pathway exclusively. The protective role of the perforin-dependent pathway has been shown for infection with the noncytopathic lymphocytic choriomeningitis virus, for infection with Listeria monocytogenes, and for the elimination of tumor cells by T cells and NK cells. In contrast, perforin-dependent cytotoxicity is not involved in protection against the cytopathic vaccinia virus and vesicular stomatitis virus. LCMV-induced immunopathology and autoimmune diabetes have been found to require perforin-expression. A contribution of perforin-dependent cytotoxicity to the rejection of MHC class I-disparate heart grafts has also been observed. Its absence is efficiently compensated in rejection of fully allogeneic organ or skin grafts. So far, evidence for a role of Fas-dependent cytotoxicity as a T cell effector mechanism in vivo is lacking. Current data suggest that the main function of Fas may be in regulation of the immune response and apparently less at the level of an effector mechanism in host defense. Further analysis is necessary, however, to settle this point finally.

Identification of arachidonic acid pathways required for the invasive and metastatic activity of malignant tumor cells

Metastasis is a complex process, almost a cascade, involving multiple steps and activities. However, an important factor is that malignant cells are able to penetrate through the multiple basement membrane barriers surrounding tissues, blood vessels, nerves and muscle that would otherwise block their dissemination. Penetration of malignant tumor cells through basement membrane is an active process requiring proteolysis. We report here that inhibitors of both the cyclooxygenase and lipoxygenase pathways of arachidonic acid metabolism convert mouse melanoma and human fibrosarcoma cells to a non invasive state by reducing the production of MMP-2, an enzyme required for the degradation of basement membranes. Specific metabolites of each pathway, i.e. PGF2 alpha and 5-HPETE, are able to transcend the block and restore collagenase production, invasiveness in vitro and metastatic activity in vivo. These studies indicate a key role for arachidonic acid metabolites in metastasis and suggest novel therapeutic approaches for inhibiting the spread of cancer.

[Effect of surgical trauma on NK cell activity in esophageal carcinoma after transmediastinal dissection vs. transthoracic en bloc resection]

In order to assess the impact of surgical trauma involved in the therapy of esophageal carcinoma on the cellular immune system, a perspective study was performed involving perioperative hematological parameters. The activity of natural killer cells and the serum concentrations of interleukin-2, interleukin-6 and TNF-alpha were measured in 12 cases of transmediastinal dissection and 10 cases of transthoracic en bloc esophageal resection and compared to values of a control group of thoracic and abdominal surgical patients with non-malignant maladies. Natural killer cells assume a central role in the non-specific immunological response in tumor patients. Their main function is the destruction of tumor cells via cytotoxic activities amplified by the release of interleukin-2 and TNF-alpha. Natural killer cell activity was measured prior to surgery and on postoperative days 4 and 10 using a standardized europium chloride release assay, utilizing K562 target cells. Lymphokines interleukin-2, interleukin-6, and TNF-alpha were also measured on postoperative days 1 and 7 using standardized ELISA assays. The activity of natural killer cells in our patient group sank significantly (P < 0.05) on postoperative day 4 and likewise in the control group and both study groups, activity sank to the original values. In the control group, natural killer cell activity averaged 45% of preoperative values, in comparison with an average of 63% following transmediastinal esophageal carcinoma resection (one cavity procedure), and transthoracic en bloc resection (two cavity procedure). On postoperative day 10, all groups displayed a significant reacceleration of natural killer cell activity (P < 0.05). Whereas transthoracic en bloc resection patients only reached 61% of preoperative values, transmediastinal dissection patients assumed 75%, and 77% was achieved by control group members. Transthoracic en bloc resection of the esophagus led to a more extreme reduction in cytotoxic cellular activity owing to the greater surgical trauma. Suppression of the immunological tumor resistance, especially in the vulnerable perisurgical phase, can have an indirect negative effect on the manifestation risk of hematogenic metastases owing to intraoperative tumor cell dissemination resulting from tumor manipulation and may thus be prognostically relevant.

Augmentation of antitumor effect by combined administration with interleukin-2 and sizofiran, a single glucan, on murine EL-4 lymphoma

The antitumor effect of the combined administration with recombinant human interleukin-2 (rIL-2) and sizofiran (SPG), a single glucan of Shizophyllum commune Fries, was studied in vivo in C57BL/6 mice intraperitoneally inoculated with EL-4 lymphoma. The effect was evaluated by a) comparing the survival time of the mice, b) analysis of the intraperitoneal cell population in Giemsa-stained specimens, c) surface marker analysis of peritoneal exudative cells with flow cytometry, d) cytotoxic assay of cells against EL-4 and Yac-1 lymphoma, and e) elimination of some cell populations by monoclonal antibodies, to identify the antitumor-effector cells showing cytotoxic activity. The survival of mice given both rIL-2 and SPG was significantly longer than the control mice or those given SPG alone or rIL-2 alone. It was demonstrated that the administration of SPG and/or rIL-2 to the EL-4 lymphoma-bearing mice activated immune-response cells in the peritoneal cavity such as T lymphocytes, NK cells, or macrophages, which might be effective in reducing lymphoma cells. The combination of rIL-2 and SPG administration appears to activate the antitumor-immune response at the tumor site more effectively than when either agent was administered alone.

Metastatic behavior of human tumors in congenitally athymic nude mice: intrinsic properties of the tumor cells and host immune reactivity

Congenitally athymic nude (nu/nu) mice have been used extensively as hosts to study the metastatic properties of xenografted human tumors. It has not been fully explored to what extent the metastatic behavior of human tumor xenografts reflects the intrinsic properties of the tumor cells and to what extent it is influenced artificially by the host. The purpose of the work reported here was to evaluate the potential usefullness of athymic mice for qualitative and quantitative assessment of the intrinsic metastatic properties of human tumor cells. Four human melanoma cell lines (A-07, D-12, R-18, U-25) were included in the study. Quantitative intradermal and intracranial transplantation assays were used to determine the tumorigenicity and immunogenicity of the cell lines. The metastatic behavior of the cell lines was studied by inoculating cells intra-arterially or intravenously (artificial metastases) or intradermally (spontaneous metastases). The influence of the host on the incidence of metastases was assessed by inoculating cells intravenously in immunologically modified athymic mice. Both the intradermal and intracranial tumorigenicity differed substantially between the cell lines. The host immune reactivity against heterotransplantation was significantly lower for D-12 than for A-07, R-18 and U-25 cells. The incidence of metastases was influenced significantly by the host immune reactivity. The cell lines showed organ-specific metastatic patterns in athymic mice. The organs of preference were lungs for A-07 and D-12 cells, lymph nodes for R-18 cells, and brain for U-25 cells. The organ-specific metastatic pattern in athymic mice reflected the pattern of distant metastases in the donor patients. In addition, all cell lines gave rise to metastases in abdominal organ sites, but without organ specificity. The incidence of abdominal metastases was influenced significantly by the tumorigenicity of the cell lines. In conclusion, athymic mice appear to be excellent hosts for assessment of the organ specificity in the metastatic behavior of human tumors. The metastasis frequency of human tumors in athymic mice, however, might be a misleading quantitative measure of the intrinsic metastatic propensity of the tumor cells, owing to the cell-line-dependent host immune reactivity.

A prospective study of tumor recurrence and the acute-phase response after apparently curative colorectal cancer surgery

BACKGROUND

Approximately 70% of patients who are going to develop tumor recurrence following curative colorectal surgery do so within 24 months of surgery.

PATIENTS AND METHODS

The relationship was prospectively examined between an ongoing acute-phase response and subsequent clinical relapse in 36 colorectal cancer patients who had undergone a curative resection. Approximately 4 months after their operation, patients were grouped according to the presence (n = 15) or absence (n = 21) of an acute-phase response (C-reactive protein > 5 mg/L) and were followed-up for a minimum of 24 months.

RESULTS

Age, tumor site, and serum carcinoembryonic antigen concentrations were similar in both groups. There was a significantly higher recurrence rate in patients with an acute-phase response (11 of 15) compared to those with no acute-phase response (2 of 21, P < 0.01).

CONCLUSIONS

These results are consistent with the presence of an acute-phase response being an important predictive factor in the early stages of tumor recurrence in patients who have had apparently curative colorectal surgery.

Polyadenylic-polyuridylic acid enhances the natural cell-mediated cytotoxicity in patients with breast cancer undergoing mastectomy

BACKGROUND

Surgical procedures suppress host antitumor defense mechanisms, which may increase the risk of metastatic tumor dissemination. We have evaluated the effects of the biologic response modifier polyadenylic-polyuridylic acid (PAPU) on natural cytotoxicity in patients with breast cancer undergoing operation.

METHODS

PAPU (150 mg) or placebo was given intravenously during the perioperative period (preoperative, days -1 and 0; postoperative, days 1, 3, 5, 7, and 14). The function (chromium release assay) and number (flow cytometry) of natural killer (NK) cells were measured before operation (days -2 and -1), on the day of operation (day 0), and after operation (days 1, 2, 4, 6, and 18).

RESULTS

Surgical procedures suppressed NK cell cytotoxicity in the placebo group on postoperative days 1 (p < 0.001), 4, 6, and 18 (p < 0.05), whereas inhibition on postoperative day 2 failed to reach significance. PAPU abolished this immunosuppression after operation. The NK cell activity was elevated when compared with the control group; it was significant (p < 0.05) on postoperative days 1, 2, 4, 6, and 18. Surgical procedures also reduced circulating NK cell numbers during the first postoperative week in the placebo group; the decrease was statistically significant on day 4. The decrease in NK cell numbers in the PAPU group was insignificant.

CONCLUSIONS

PAPU prevented the decrease in the circulating number and cytotoxic activity of NK cells that occurred after operation and enhanced NK cell cytotoxicity. This may have important implications for patients with cancer undergoing major operation.

The addition of interleukin-2 to cyclophosphamide therapy can facilitate tumor growth of B16 melanoma

The role of interleukin-2 (IL-2) on tumor growth of B16F10 melanoma cells was assessed in two sets of mice with different immune status: normal (immunocompetent) mice and immunodeficient mice. The two sets of animals were treated with cyclophosphamide (CY) or IL-2 alone or with a combined therapy of CY+IL-2. On days 6 and 10 after tumor cell injection, we evaluated the incidence of hepatic B16 melanoma metastases and the percentage of hepatic volume occupied by metastatic tissue. We observed that the CY alone (300 mg/kg, days 3 and 8 post-tumoral inoculation) significantly reduced tumor growth in all treated mice; however, CY proved more effective in normal recipients than in immunodeficient hosts. On the other hand, whereas administration of IL-2 alone (10(5) IU daily, from day 3 to day 7) in immunocompetent mice significantly reduced tumor growth on days 6 and 10, in immunodeficient mice, no significant differences were observed in tumor growth either on the 6th or on the 10th day, in comparison to control groups. Finally, when the combined CY+IL-2 therapy was administered, an antisynergistic effect between these therapeutic agents was achieved both in normal and in immunodeficient mice. Thus, the addition of low-dose IL-2 (25 x 10(3) IU daily, from day 4 to day 7) to high-dose CY (300 mg/kg, days 3 and 8) significantly increased tumor growth in both the early and later periods, compared to the effect of CY alone. It is concluded that exogenous IL-2 can facilitate tumor growth of B16 melanoma cells in vivo.

Role of histamine in natural killer cell-dependent protection against herpes simplex virus type 2 infection in mice

Depletion of natural killer (NK) cells in vivo with anti-NK1.1 monoclonal antibody or anti-asialo-GM1 antiserum drastically reduced survival time in Swiss albino mice infected intravenously (i.v.) with herpes simplex virus type 2 (HSV-2). In contrast, depletion of NK cells did not affect the survival time of mice inoculated with HSV-2 by the intraperitoneal route. A single dose of histamine prolonged survival time in animals inoculated with HSV-2 i.v. but not in animals infected intraperitoneally. Treatment with the histamine H2 receptor antagonist ranitidine alone reduced survival time in i.v.-infected animals and blocked the protective effect of histamine. Histamine or ranitidine did not affect survival time in anti-NK1.1- or anti-asialo-GM1-treated animals. Our data suggest a role for histaminergic mechanisms in NK cell-mediated protection against HSV-2.

Transfection with the inducible nitric oxide synthase gene suppresses tumorigenicity and abrogates metastasis by K-1735 murine melanoma cells

Previous studies from our laboratory demonstrated an inverse relationship between the expression level of inducible nitric oxide synthase (iNOS) and the metastatic potential of murine K-1735 melanoma cells. The purpose of this study was to provide direct evidence that the expression of iNOS suppresses metastatic potential of melanoma cells. Highly metastatic K-1735 clone 4 cells (C4.P), which express low levels of iNOS, were transfected with a functional iNOS (C4.L8), inactive-mutated iNOS (C4.S2), or neomycin-resistance (C4.Neo) genes in medium containing 3 mM NG-methyl-L-arginine (NMA). Positive transfectants were identified by Southern and Northern blot analyses and homogeneous staining with a specific anti-iNOS monoclonal antibody. Semiconfluent cultures of C4.P (parental), C4.Neo.3 (control transfection), C4.S2.3 (inactive iNOS), and C4.L8.5 (functional iNOS) were harvested, and viable cells were injected intravenously into syngeneic C3H/HeN mice and allogeneic BALB/c nude mice. C4.P, C4.Neo.3, and C4.S2.3 cells were highly metastatic whereas C4.L8.5 cells were not metastatic. Experiments with [125I]dUrd-labeled tumor cells demonstrated that the initial arrest in the lung microvasculature did not differ among the lines, but that C4.L8.5 cells died by 48-72 h after injection. Enhanced survival of all K-1735 C4 cells (including C4.L8.5) was found in mice given twice daily injections of 20 mg NMA. The C4.L8.5 cells produced slow growing subcutaneous tumors in nude mice, whereas the other three lines produced fast growing tumors. In vitro studies confirmed that in the absence of NMA the expression of iNOS in C4.L8.5 cells induced apoptosis. Collectively, these data demonstrate that the expression of recombinant iNOS in melanoma cells is associated with apoptosis, suppression of tumorigenicity, and abrogation of metastasis.

Determinants of differential liver-colonizing potential of variants of the MCA-38 murine colon cancer cell line

We investigated factors that might contribute to the differing liver tumor colonizing potentials of MCA-38 colonic cancer cell line variants injected into the ileocolic veins of C57Bl/6J mice. Non-colonizing (MCA-38 CD) cells were sensitive to lysis by hepatic natural killer (NK) cells in vitro (51Cr-release assay) and cells with high liver-colonizing potential (MCA-38 LD) were resistant. Following abrogation of NK activity by treatment with anti-asialoGM1, liver-colonizing ability to LD cells but not CD cells was enhanced. MCA-38 CD cells were, however, capable of initial liver colonization after ileocolic vein injection. Differing patterns of membrane sialylation may have contributed to the contrasting hepatic tumorigenicities of LD and CD cells; beta-galactoside alpha 2,6-sialyltransferase mRNA levels and activity were approximately four-fold higher in LD than CD cells and qualitative and quantitative differences existed between their ganglioside profiles. In the MCA-38 model outlined, tumor cell susceptibility or resistance to NK lysis was a relatively unimportant determinant of liver-colonizing potential.

Effect of blood transfusion in patients with gynecologic malignancy

OBJECTIVES

To determine the effect of blood transfusion on long-term outcome (disease-free interval, recurrence of disease after treatment, and survival) in women with invasive gynecologic malignancy.

METHODS

In this retrospective study, 125 patients with gynecologic malignancy were assessed over a 36-month period. The variable of whether patients received blood transfusion during therapy was used to divide the sample into two groups.

RESULTS

There were no differences in the age, ethnicity, and site-stage of tumor of the two groups. Treatments (surgery, radiotherapy, chemotherapy, or multimodal) were similar between the two groups, as were initial hematocrits. The disease-free interval was significantly better in women who did not receive homologous blood (P < 0.001). Life table analysis illustrated that more patients were alive and free of disease if they did not receive blood (P < 0.001). Likewise, persistence-recurrence of cancer was more common in the transfusion group (P < 0.001). Finally, overall survival time was adversely affected by transfusion (P = 0.045).

CONCLUSIONS

The use of blood products in patients with invasive gynecologic cancer is associated with enhanced recurrence or persistence of malignancy, a decrease in the disease-free interval, and reduction in the probability of survival without evidence of disease.

Effect of arginase on splenic killer cell activity in patients with gastric cancer

Arginase has been detected in high levels in gastric cancer tissues. The effect of arginase on the activities of splenic natural killer (NK) cell, phytohemagglutinin activated killer (PAK) cell, and interleukin-2 activated killer (LAK) cell in patients with gastric cancer (N = 12) was evaluated in vitro. These activities in patients (N = 10) with trauma and benign lesions were used as control. The splenic NK and PAK cell activities in patients with gastric cancer were significantly lower than in the controls (P < 0.05), whereas LAK cell activity did not have significant difference. Arginase inhibited all splenic killer cell activities to a similar degree between patients with gastric cancer and the controls. The inhibition was dose-related. These data suggest that arginase may play a positive role in the spread of gastric cancer cells. However, LAK may be a potential approach of immunoadoptive therapy in the future.

Further studies of the therapeutic effects of murine melanoma-specific monoclonal antibodies

The results presented here further characterize four murine monoclonal antibodies (mAb) that recognize melanoma-specific antigens (9B6, T97, 2-3-1 and 2-3-3). These melanoma-specific mAbs are of the IgG2b isotype and are significantly therapeutic when administered systemically against established pulmonary melanoma metastases. Here we show a consistent and significant inhibition of the growth of melanoma lung metastases by all four mAbs and the existence of a time 'window' at days 5-8 after tumor inoculation for optimal therapy. Since these mAbs were found not to be cytotoxic or cytolytic in vitro, we looked for host immune response regulation as being responsible for the therapeutic effects. Natural killer (NK) cells were implicated as one arm of the host immune system involved in this response since depletion of NK cells in vivo by alpha asialoGM1 or alpha NK1.1 antibodies partially abrogated the inhibitory effect of the mAbs. The observed antimetastatic effects could also be partially abrogated using antibodies directed against the T-cell subset surface markers, CD4+ and CD8+. Intramuscular melanoma tumor growth was also found to be suppressed by mAb 2-3-1, but only if administered in the area of tumor growth and only if multiple inoculations are administered over a 13-day period. The beneficial effect of mAb antimetastatic therapy was found to be useful against several syngeneic melanomas, including JB/MS, B16 and several sublines of the B16 F10 melanoma.

Allogeneic blood transfusion reduces murine pulmonary natural killer (NK) activity and enhances lung metastasis of a syngeneic tumour

A model was established whereby C57BL/6 (B6) blood injected i.v. into C3H mice 7 days prior to i.v. injection of syngeneic UV-2237 tumour cells significantly increased the number of pulmonary metastases counted 21 days later as compared with levels observed in mice treated with saline, C3H or NZW blood or SRBC. This regimen of B6 allogeneic blood transfusion of C3H mice also significantly depressed splenic and pulmonary NK activity as assayed by lysis of 51Cr YAC-I in vitro and by clearance of 111In YAC-I in vivo respectively. Anti-asialo GMI treatment, which depletes NK activity in vivo, and Poly I:C treatment, which enhances NK activity in vivo, were associated with significantly increased and decreased pulmonary metastasis of UV-2237, respectively, in C3H mice. Depletion of CD4+ and CD8+ T cells had no effect. Cyclophosphamide pretreatment which, among other effects, depletes NK cells, significantly increased pulmonary metastasis of UV-2237 in C3H mice. This was corrected by adoptive transfer of normal C3H spleen cells but not spleen cells from anti-asialo GMI-treated C3H mice or B6-blood-transfused C3H mice. Furthermore, a 1:1 mixture of normal C3H spleen cells with spleen cells from B6-blood-transfused C3H mice also failed to reconstitute the cyclophosphamide-pre-treated C3H mice. We conclude that allogeneic blood transfusion augments pulmonary metastasis of the UV-2237 sarcoma in C3H mice and that the mechanism involves suppression of NK activity.

Impaired interferon production and natural killer cell activation in patients with the skin cancer-prone disorder, xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder with sun sensitivity, markedly increased skin cancer susceptibility, and defective DNA repair without consistently identified symptoms of immune deficiency. We examined natural killer (NK) cell activity and interferon production in peripheral blood lymphocytes (PBL) of eight XP patients who had multiple primary skin cancers. The XP patients had normal numbers of T cells and NK cells, as well as normal lymphokine-activated killer cell activity and normal tumor necrosis factor-alpha production. Unstimulated NK cell function was 40% of normal controls in five XP patients, but was normal in three other XP patients. However, PBL from all the XP patients tested showed no enhancement of NK activity by the interferon inducer, polyinosinic acid:polycytidilic acid (polyIC) but enhancement by interferon-alpha was normal, suggesting an impairment in interferon production. Parallel studies in non-XP skin cancer patients revealed that both unstimulated and polyIC-enhanced NK activity were normal. Further investigation using PBL from XP patients revealed that the production of interferon-gamma after stimulation with interferon inducers (polyIC, interleukin 2, or K562 tumor cells) was 13-43% of normals. These data indicate that XP lymphocytes have a defect in production of interferons and suggest that defective interferon production, as well as DNA repair defects, may play an important role in the susceptibility of XP patients to skin cancer.

Blood transfusion and the risk of recurrence in squamous carcinoma of the vulva

OBJECTIVE

Our purpose was to determine if postoperative transfusion increases the risk of recurrence in patients who have undergone operation for squamous carcinoma of the vulva.

STUDY DESIGN

Data from 154 patients with squamous carcinoma of the vulva treated at Indiana University Medical Center from 1974 through 1988 were retrospectively analyzed to determine the influence of postoperative transfusion on recurrence risk. Patients were evaluated for International Federation of Gynecology and Obstetrics stage, lesion size, lesion depth, grade, patient age, number of transfusions, and recurrence with chi 2 analysis, Fisher's exact test, and the Student t test where appropriate.

RESULTS

Transfusions were given to 57 patients (37%) with a mean of 2.2 units delivered (range 1 to 5 units). Transfused patients differed significantly from those not transfused in that they had more advanced stage (p = 0.002), more positive nodes (p = 0.03), and higher grade lesions (p = 0.03), and they were older (p = 0.005). Recurrences developed in 25 patients (16.2%). Recurrences were more common in those with positive nodes (10-39, 25.6%) than in those with negative nodes (8/99, 8%), (p = 0.01). Only nodal status was predictive of recurrence in this series. Transfused patients had a 14% (8/57) rate of recurrence, whereas the recurrence risk was 17.5% (17/97) in those not transfused (p = 0.65).

CONCLUSIONS

We have been unable to confirm that postoperative transfusions increase the risk of recurrence in patients with squamous carcinoma of the vulva.

The spleen can influence the metastasis of AH130 hepatoma cells in rats

The effect of pathophysiological conditions due to disturbance of the spleen is still unclear. We studied the effects of splenectomy in normal and methylcellulose-induced hypersplenic rats on the development of pulmonary metastases created by intravenous injection of ascites containing AH130 hepatoma cells from male Hos-Donryu rats. Growth of metastatic lesions in the lung was not affected by splenectomy in normal rats, but was increased by splenectomy in hypersplenic rats. Overall, there were fewer pulmonary metastases in rats with hypersplenism, but after splenectomy rats with hypersplenism had a significantly greater number of metastases than did normal rats. The metastases rate correlated somewhat with changes in the blood coagulation and T lymphocyte profile. There is a relationship between the spleen and formation of metastases in cancer. Formation of metastases in the lung was affected most by splenectomy in hypersplenism. To elucidate the mechanism by which metastases are formed in the lung under these pathologic conditions, further studies on the exact role of the spleen are required.

Significance of platelets in an antimetastatic activity of bacterial lipopolysaccharide

Recently we reported an antimetastatic activity of bacterial lipopolysaccharide (LPS) on a NK-cell-resistant murine fibrosarcoma (NFSa). Here we investigate and report the mechanistic significance of platelets in this activity. The number of circulating platelets was reduced to 63% of the control 3 days after an i.v. injection of 1.0 micrograms LPS, and then recovered to the level of control at day 10. Aggregation efficiency of platelets was impaired by LPS. The number of metastatic lung colonies after an i.v. injection of tumor cells was maximally reduced to 2.2% of the control at day 3 and increased in proportion to the recovery of platelet number. Neuraminidase (Ndase), which caused a non-immunological thrombocytopenia, also inhibited lung metastasis when injected prior to an i.v. tumor cell challenge. LPS and Ndase showed an identical pattern against five other syngeneic tumors; these agents inhibited lung metastases of the FSa fibrosarcoma and the SCC VII squamous cell carcinoma but failed to inhibit those of the NR-S1 squamous cell carcinoma, the MMCa#4 mammary adenocarcinoma and the NR-PG parotid gland tumor. All the three cells which were not responsive to any agents possessed a high aggregating activity of platelets while the other three tumors responsive to both agents did not show a detectable level of this activity. Platelet transfusion failed to modify the antimetastatic activity of LPS. These results suggest that platelets play an important role in the antimetastatic activity of LPS, though whether the role is principal or assistant remains to be seen.

Naloxone modulates NK-cell activity of human peripheral blood lymphocytes like an opioid agonist

Naloxone at concentrations 10(-6) M to 10(-10) M modulated endogenous NK-activity in 11 of 14 samples of human peripheral blood lymphocytes after 18-hour incubation. The dose response usually showed two peaks, which varied with the donor. Enhancement was obtained in 6, suppression in 4, and both effects (depending on naloxone concentration) in 1 example; 3 donors were nonresponders. However, the overall effect of naloxone on endogenous NK activity was not statistically significant in the population as a whole. IL-2-stimulated NK-activity, was also altered by naloxone. The direction of the alteration depended on the degree of IL-2-induced NK-stimulation, and was donor-dependent. For example, naloxone enhanced NK-activity that had been stimulated by low IL-2 concentration (3 U/ml), but decreased NK-activity which had been stimulated by high (50 U/ml) IL-2 concentration. Naloxone 10(-7) M significantly reversed medium stimulation of NK activity, induced by 25 U/ml, in a group as a whole. Naloxone (10(-7) M to 10(-12) M) also modulated NK-activity stimulated by exogenous IFN alpha, as well as by endogenous, Poly-I.C-induced IFN. Decrease, or enhancement, depended on the degree of baseline NK-stimulation and varied with the donor. Short (2-hours) incubation with naloxone also resulted in the modulation of basal and IFN-stimulated NK-activity. Again, the effect varied with the donor and with the degree of lymphocyte activation. Thus, naloxone, the opioid receptor antagonist, modulated the NK-cell activity like opioid peptides, i.e. resembled an opioid agonist, in an individual, donor dependent fashion.

Isolation and characterization of a low metastatic variant from EL-4 mouse T-lymphoma

A variant cell line (EL-4ad) which adhered to a tissue culture dish was isolated from highly metastatic EL-4 murine T-lymphoma. The experimental and spontaneous metastatic ability of EL-4ad was lower than that of the EL-4 parent cell line. The cell surface phenotypes of both cell lines were CD2+3+4-8-45+TCR alpha beta+TCR gamma delta-, but the level of CD2 expression of EL-4ad was much lower than that of EL-4. Furthermore, EL-4ad had higher binding ability to fibronectin and expressed more PNA receptors on the cell surface than EL-4. These differences indicated that either the maturation stage of the less metastatic variant was lower than that of the parent cell line or the activation state of the two cell lines differed. EL-4ad showed higher in vitro invasiveness and adhesiveness to liver cells, and these characters were not consistent with the reduced metastatic ability of this variant. Neuraminidase-releasable cell surface sialic acid levels did not differ significantly between the cell lines. Neither cell line was adhesive to laminin, type IV collagen or reconstituted basement membrane. These metastasis-related properties could not explain the decreased metastatic ability of EL-4ad. On the other hand, EL-4ad was more sensitive to NK activity than EL-4 in vivo, and this was thought to be a major cause of its decreased metastatic ability. The molecules or mechanisms involved in the differentiation or activation of T-cells may be responsible for the sensitivity of tumor cells to NK activity.

The Immunosuppressive Aspects of Blood Transfusion

Blood transfusion is associated with immunosuppression, although the exact etiology of the immunosuppressive effect is not fully understood. The clinical significance of the immunosuppressive effect of blood transfusion has been examined in three situations: (1) studies of renal allograft survival after renal transplantation, (2) outcome studies in patients who have had surgical resection of solid cancer tumors, and (3) studies of infection rates in postoperative patients. In each scenario, the data support the conclusion that transfusion is associated with immunosuppression as manifested by increased renal allograft survival, increased recurrence and mortality rates in patients with cancer, and increased infection rates in postoperative patients who are transfused. Not all studies demonstrate an immunosuppressive effect of transfusion. There are several possible explanations for these discrepancies. First, prognostic variables other than transfusion itself account for the outcome results in these retrospective studies. Second, the extent of immunosuppression may be influenced by the type of blood product transfused, the amount transfused, and the timing of the transfusion; these factors have not been considered in all studies. For example, whole blood has been implicated as having a greater immunosuppressive effect than packed red blood cells, and many studies have shown that more than three units of packed red blood cells are necessary to affect outcome. Controlled animal studies have tested the hypothesis that transfusions increase solid tumor growth or the risk for infection. These studies have yielded conflicting results. Nevertheless, evidence that blood transfusion influences clinical outcome mitigates that a decision to transfuse must consider both risks and benefits of a transfusion; the possible consequences of immunosuppression must be included among the risks. Use of autologous blood, erythropoietin, and, in the future, synthetic hemoglobin may lead to improved outcome in patients with certain disease processes.

Immunomodulation by orally administered protein-bound polysaccharide PSK in patients with gastrointestinal cancer

The present study was designed to assess the effects of the protein-bound polysaccharide PSK on the immunological status of patients with gastrointestinal cancer. Twenty-nine gastric and 18 colorectal cancer patients were randomly assigned to either the control or PSK group. Patients in the PSK group were given 3.0 g of PSK orally before surgery, either daily or every other day. Patients in the control group received no PSK. The data of peripheral blood lymphocytes (PBL) were compared before and after administration of PSK, and those of the regional node lymphocytes (RNL) were compared between the control and the PSK group. The results indicate that the effects of PSK were significantly influenced by the duration of administration, but not by the frequency of administration. In the patients belonging to the short term PSK group (administration less than 14 days), the response of the PBL to PSK and Con A become significantly stronger compared to before the administration of PSK, whereas the cytotoxicity against K562 and KATO-3, and the proportion of CD16+ cells increased significantly in those patients belonging to the long term PSK group (greater than or equal to 14 days). In addition, the proportion of CD9 + 11b + suppressor T cells decreased in the RNL of the short term PSK group, whereas the proportion of CD4 + Leu8 - helper T cells in the RNL increased in the long term PSK group. These results suggest that the oral administration of PSK leads to the suppression of suppressor cells in the RNL.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental metastasis of oncogene-transformed NIH 3T3 cells in chick embryo

By means of a highly sensitive and quantitative assay for specific detection of metastasized tumor cells in chick embryonic organs using the polymerase chain reaction (PCR), we have examined the experimental metastatic ability of individual clones of NIH 3T3 cells, transformed with oncogenes: v-Ki-ras, v-Ha-ras, v-src, v-fos, and v-abl. Such a transformed clone had different metastatic abilities in different embryonic organs. Among them, two clones of NIH 3T3 cells transformed with ras-oncogenes (v-Ki-ras or v-Ha-ras) metastasized to liver and lungs of chick embryo, and grew there more rapidly than the other clones. The parental NIH 3T3 cells were detected as slight bands of PCR products after iv injection, indicating some cells were trapped in chick embryonic organs, but did not grow. These findings indicate that the transformed cells are able to invade the organ tissues and grow in embryonic chick organs, but non-metastatic cells such as the untransformed-NIH 3T3 cells are not able to grow in the secondary sites. These experiments clearly demonstrate the usefulness of this assay system to study genes involved in malignant transformation.

The biological effects of immunosuppression on cellular immunotherapy

Cytoreductive chemotherapy and immunosuppression have been postulated as possible adjuncts to cancer immunotherapy in studies using murine tumour-infiltrating lymphocytes (TIL). Treatment of animals with cyclophosphamide (Cy) therapy alone caused two distinct biological activities that altered the relationship between host and tumour. These two in vivo activities were distinguished by altering the timing and dose of Cy administration relative to tumour implantation. Cy administered 3 days following tumour injection caused a significant decline in the number of pulmonary micrometastases and greater survival compared to untreated controls in proportion to the dose of Cy administered. Further reduction in pulmonary disease was observed when Cy-treated mice were given TIL therapy. The possible role(s) of Cy-induced immunosuppression was studied by injecting Cy 24 h prior to tumour injection. This treatment failed to cause the cytoreductive effect observed when Cy was administered 3 days after tumour since Cy-administration prior to tumour resulted in a significantly higher number of pulmonary metastases and diminished survival compared to untreated controls. Despite the increased number of pulmonary metastases and decreased survival in mice treated with Cy before administration of tumour, therapy with TIL significantly diminished pulmonary disease compared to animals treated with Cy alone. Immunosuppression (without concomitant cytoreductive therapy) prior to TIL treatment significantly prolonged survival. Additional studies with TIL therapy indicate that the survival of animals immunosuppressed prior to tumour injection was significantly longer than controls which received immunotherapy alone. These results suggest that the combustion of immunosuppression plus cellular immunotherapy, which leads to significant survival advantage in these murine tumour models, may possibly augment the clinical response in human TIL trials.

Search for anti-metastatic therapy: effects of phenytoin on B16 melanoma metastasis

The ability to metastasize requires that tumor cells be able to degrade matrix. Nontoxic compounds that inhibit matrix digestion might be useful as anti-metastatic agents. We have investigated whether phenytoin, a drug commonly used in clinical practice that inhibits the production of collagenase by some cells, inhibits metastases in a standard animal model of metastasis: In vitro, phenytoin inhibited the proliferative response of B16 F10 melanoma cells to serum-containing media (75% inhibition at 25 micrograms/ml) but had no effect on their ability to degrade a type I collagen gel (1-100 micrograms/ml). Treatment of these cells with phenytoin prior to inoculation in vivo did not inhibit tumor growth, implantation in a surgical wound, or incidence of spontaneous metastases from a primary tumor growing in the foot. Pretreatment of mice with phenytoin (15, 40, and 75 mg/kg/day) diminished pulmonary metastases following tail vein injection in a minimal but dose dependent fashion; mean number of pulmonary colonies 4.6 +/- 3.1 (75/mg/kg/day) vs. 10.2 +/- 9.9 (control). However, tumor growth, implantation, and spontaneous metastases were not inhibited by pretreating the mice with the same doses of phenytoin. It is concluded that phenytoin has an insignificant inhibitory effect on tumor growth and metastasis.

Population dynamics of natural killer cells in the spleen and bone marrow of normal and leukemic mice during in vivo exposure to interleukin-2

By quantitative and functional methods, changes were assessed in NK(ASGM-1+) cell numbers and NK cell-mediated lytic function of the spleen and bone marrow of mice bearing a tumor of hemopoietic origin (FLV-induced erythroleukemia) for 9 days +/- simultaneous administration of indomethacin (10 micrograms/ml drinking water) +/- rIL-2 (3x/day, 12 x 10(3) Units/injection) during the last 4 days of tumor-bearing. Recombinant IL-2 alone during the last 4 days of tumor-bearing increased both the NK(ASGM-1+) cell numbers (p less than 0.001) and the functional activity (24-fold) of the spleen. In the bone marrow, however, no change in the numbers of NK(ASGM-1+) cells was observed relative to untreated tumor-bearing mice, but the NK cell-mediated lytic activity of that organ was augmented 30-fold. The continuous presence of indomethacin from the onset of tumor-bearing prior to rIL-2 treatment during the last 4 days of tumor-bearing, further boosted both the already high, rIL-2 driven numbers of NK(ASGM-1+) cells in the spleen (p less than 0.01), as well as splenic NK cell lytic function (2-fold). In the bone marrow, continuous presence of indomethacin prior to and during the terminal 4 days of co-administration with rIL-2 increased 3-fold the numbers of NK(ASGM-1+) cells relative to that of the bone marrow of tumor-bearing mice given rIL-2 alone, and resulted in lytic activity of that organ which was 140% of that of the rIL-2 treated, tumor-bearing mice. The results indicate that under the combined influence of indomethacin and rIL-2, the production of NK(ASGM-1+) cells was augmented in the bone marrow of tumor-bearing mice, export of immature NK(ASGM-1+) cells from the bone marrow was increased, and import of immature NK(ASGM-1+) cells by the spleen was increased. The increased NK(ASGM-1+) cell numbers in each organ was reflected in increased lytic function.

Active components of intestinal bacteria for abdominal irradiation-induced inhibition of lung metastases

We have previously reported that abdominal irradiation of mice inhibited lung metastases of a weakly immunogenic fibrosarcoma, and that transmigration after the irradiation of Enterobacter cloacae into mesenteric lymph nodes coincided with this phenomenon. In this paper, we show that Escherichia coli as well as E. cloacae reduce the number of metastatic lung colonies when these bacteria were intravenously injected into mice prior to the tumour cell challenge. The inhibition was caused not only by the administration of living bacteria but also by that of killed bacteria. Bacterial lipopolysaccharide (LPS), a component of membrane, replaced at least in part the effect of whole bacteria. Transfer of spleen cells from LPS-treated mice into intact recipients prominently inhibited metastatic development in the recipient mice. 'Cross transfer' between LPS high responders and LPS low responders suggested an indirect activity of transferred spleen cells. The antimetastatic activity of LPS depended on the tumour cell type; metastasis of fibrosarcomas was extensively inhibited by LPS irrespective of tumour immunogenicity while that of adenocarcinomas was only slightly inhibited. These results suggest that non-immunological mechanisms are involved in the antimetastatic activity of LPS.

MHC antigens on human tumors

MHC class I antigens on tumor cells are expected to play an important role because they regulate the sensitivity to antitumoral immunological mechanisms. Overall or selective qualitative or quantitative changes in MHC molecules may modify the recognition of tumor cells by components of the immune system. It seems clear that MHC antigen expression on tumor cells is important in triggering the immune response by autologous lymphocytes. A deficiency in or lack of MHC class I antigens may have profound effects on T and NK cell activity. In experimental models, variation in the expression of MHC class I antigens has been shown to exert a decisive influence on local tumor growth and metastasis. However, there is little information about the influence of selective loss of individual locus products on the behavior of human tumor cells. Total and selective HLA losses have been found in a large variety of tumors, and different mechanisms have been shown to be responsible for these changes. In some examples, HLA losses are associated with a poor degree of tissue differentiation and poor prognosis. In other tumors, however, no such association has been found. We do not know whether HLA class II expression in neoplastic cells plays an immunological role, although, with the exception of melanoma, HLA class II expression is more frequently observed in tumors with a more favorable prognosis. Finally, there is no doubt that we need to learn more about how to manipulate the expression of MHC class I and II antigens in human tumors, in order to stimulate immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of splenectomy on pulmonary metastasis and growth of SC42 carcinoma transplanted into mouse liver

The carcinoma SC42 was transplanted into the liver of its syngeneic mice DS, and the immunological integrity of the spleen and the effects of splenectomy on the growth and pulmonary metastasis of the liver tumor were assessed. On day 7 after liver tumor transplantation, the natural killer (NK) activity of the splenocytes was significantly elevated; it subsequently decreased at a later stage of the tumor. The response of the splenocytes to PHA and Con-A decreased significantly from the early stage of the tumor. However, the mixed lymphocyte-tumor cell reaction increased significantly from day 14 to day 28. The survival rate of the mice, which had undergone simultaneous splenectomy and liver tumor transplantation, was significantly lower than that of sham-operated control mice. The number of pulmonary metastases in splenectomized mice was significantly greater than in the control mice. There was, however, no difference between the two groups in the weight of the liver tumor. By contrast, splenectomies performed 14 days before or 14 days after tumor transplantation had no significant influence on the survival of the mice. Splenectomies performed on day 0 and on day 3 after tumor transplantation significantly increased the number of pulmonary metastases. Furthermore, the intravenous injection of anti-asialo GM1 antisera on day 0 and day 3 significantly increased the number of pulmonary metastases, but injection of anti-Thy 1.2 antisera had no effect. These results suggest that splenic NK cells may play an important role in the suppression of pulmonary metastasis at early stages of the liver tumor.