The emergence of social cognitive neuroscience

Social cognitive neuroscience is an emerging interdisciplinary field of research that seeks to understand phenomena in terms of interactions between 3 levels of analysis: the social level, which is concerned with the motivational and social factors that influence behavior and experience; the cognitive level, which is concerned with the information-processing mechanisms that give rise to social-level phenomena; and the neural level, which is concerned with the brain mechanisms that instantiate cognitive-level processes. The social cognitive neuroscience approach entails conducting studies and constructing theories that make reference to all 3 levels and contrasts with traditional social psychological and cognitive neuroscientific research that primarily makes reference to 2 levels. The authors present an introduction to and analysis of the field by reviewing current research and providing guidelines and suggested directions for future work.

Do amnesics exhibit cognitive dissonance reduction? The role of explicit memory and attention in attitude change

In two studies, we investigated the roles of explicit memory and attentional resources in the process of behavior-induced attitude change. Although most theories of attitude change (cognitive dissonance and self-perception theories) assume an important role for both mechanisms, we propose that behavior-induced attitude change can be a relatively automatic process that does not require explicit memory for, or consciously controlled processing of, the discrepancy between attitude and behavior. Using a free-choice paradigm, we found that both amnesics and normal participants under cognitive load showed as much attitude change as did control participants.

Why introverts can't always tell who likes them: multitasking and nonverbal decoding

Despite personality theories suggesting that extraversion correlates with social skill, most studies have not found a positive correlation between extraversion and nonverbal decoding. The authors propose that introverts are less able to multitask and thus are poorer at nonverbal decoding, but only when it is a secondary task. Prior research has uniformly extracted the nonverbal decoding from its multitasking context and, consequently, never tested this hypothesis. In Studies 1-3, introverts exhibited a nonverbal decoding deficit, relative to extraverts, but only when decoding was a secondary rather than a primary task within a multitasking context. In Study 4, extraversion was found to correlate with central executive efficiency (r = .42) but not with storage capacity (r = .04). These results are discussed in terms of arousal theories of extraversion and the role of catecholamines (dopamine and norepinephrine) in prefrontal function.

Pancreatic anastomotic failure after pancreaticoduodenectomy

BACKGROUND

Pancreatic anastomotic failure has historically been regarded as one of the most feared complications after pancreaticoduodenectomy.

METHODS

We reviewed our recent experience (59 cases), March 1994 to December 1998, with pancreaticoduodenectomy and compared preoperative and intraoperative characteristics as well as outcomes in those patients who experienced (n = 10) versus those who did not experience a postoperative pancreatic leak (n = 49). Information was retrospectively collected from hospital records, office records, and interviews with patients.

RESULTS

The clinical leak rate in this series was 8.5%. There were no significant differences in preoperative or intraoperative characteristics comparing those with versus those without a postoperative pancreatic leak. Only 1 of 10 patients with a postoperative pancreatic leak required reoperation to manage the leak. Those with a pancreatic leak had more other postoperative complications (median 2 versus 0 complications per patient, P = 0.01) and longer hospital duration compared with those without a leak (median 13 versus 23 days, P<0.01). Overall mortality in the series was 3.4%; no mortalities occurred as a result of a pancreatic leak.

CONCLUSIONS

In the 1990s pancreatic anastomotic leak remains a potentially lethal problem after pancreaticoduodenectomy. Pancreatic leakage after pancreaticoduodenectomy is associated with other postoperative complications and a longer hospital stay.

Intuition: a social cognitive neuroscience approach

This review proposes that implicit learning processes are the cognitive substrate of social intuition. This hypothesis is supported by (a) the conceptual correspondence between implicit learning and social intuition (nonverbal communication) and (b) a review of relevant neuropsychological (Huntington's and Parkinson's disease), neuroimaging, neurophysiological, and neuroanatomical data. It is concluded that the caudate and putamen, in the basal ganglia, are central components of both intuition and implicit learning, supporting the proposed relationship. Parallel, but distinct, processes of judgment and action are demonstrated at each of the social, cognitive, and neural levels of analysis. Additionally, explicit attempts to learn a sequence can interfere with implicit learning. The possible relevance of the computations of the basal ganglia to emotional appraisal, automatic evaluation, script processing, and decision making are discussed.

Regional treatment of hepatic micrometastasis by adenovirus vector-mediated delivery of interleukin-2 and interleukin-12 cDNAs to the hepatic parenchyma

We hypothesize that adenovirus (Ad) vector-mediated delivery of the human interleukin-2 (IL-2) cDNA (AdIL2) or the murine IL-12 cDNA heterodimer (AdIL12) would produce high concentrations of cytokines in the local hepatic milieu to induce host responses sufficient to inhibit the growth of experimental colon carcinoma-derived hepatic metastases. Ad vectors administered intravenously, which is a route known to deliver >90% of the vector to the hepatic parenchyma, achieved significant levels of each cytokine locally, with minimal levels in the sera. To examine the therapeutic effect, the AdIL2 and AdIL12 vectors were evaluated in a hepatic metastasis model that was established by injecting 3 x 10(4) cells from the poorly immunogenic syngeneic C26 colon carcinoma cell line into the right lobe of the livers of BALB/c mice. Animals received AdIL2, AdIL12, or control virus (10(8) plaque-forming units each) intravenously for 2 days after tumor implantation, and tumor growth was compared with naive controls. The AdNull control tumors measured 116 +/- 25 mm2 at 2 weeks. The control virus showed no significant antitumor effect. In marked contrast, both AdIL2 and AdIL12 vectors that were delivered regionally had significant antitumor effects, with AdIL2-treated animals having an average tumor size of 16 +/- 8 mm2; AdIL12-treated tumors measured 6 +/- 6 mm2 (P < .01, both compared with control). Both the AdIL2 and AdIL12 vectors provided a significant survival advantage by log-rank analysis (P < .01), but only AdIL12 translated into an increase in mean survival from 27 (naive control) to 37 days. To evaluate whether these antitumor effects were T-cell-mediated, splenocytes from AdIL2-treated, AdIL12-treated, and naive control groups were stimulated in vitro with gamma-irradiated C26 tumor cells for 5 days and tested for C26 tumor cell cytolysis by an in vitro cytotoxicity assay. Splenocytes from both AdIL2- and AdIL12-treated animals showed a dose-dependent, T-cell-mediated, specific cytolysis of CT26 cells. AdIL12 and to a lesser extent AdIL2 induced natural killer cell activity, as determined by a dose-dependent increase in lysis of the natural killer-specific target cell YAC-1. Overall, these data suggest that regional Ad-mediated delivery of IL-2 and IL-12 cDNAs may be useful for local tumor control and may warrant further investigation as a potentially useful adjuvant for the treatment of hepatic micrometastasis.

Variability of human systemic humoral immune responses to adenovirus gene transfer vectors administered to different organs

Administration of adenovirus (Ad) vectors to immunologically naive experimental animals almost invariably results in the induction of systemic anti-Ad neutralizing antibodies. To determine if the human systemic humoral host responses to Ad vectors follow a similar pattern, we evaluated the systemic (serum) anti-Ad serotype 5 (Ad5) neutralizing antibodies in humans after administration of first generation (E1(-) E3(-)) Ad5-based gene transfer vectors to different hosts. AdGVCFTR.10 (carrying the normal human cystic fibrosis [CF] transmembrane regulator cDNA) was sprayed (8 x 10(7) to 2 x 10(10) particle units [PU]) repetitively (every 3 months or every 2 weeks) to the airway epithelium of 15 individuals with CF. AdGVCD.10 (carrying the Escherichia coli cytosine deaminase gene) was administered (8 x 10(8) to 8 x 10(9) PU; once a week, twice) directly to liver metastasis of five individuals with colon cancer and by the intradermal route (8 x 10(7) to 8 x 10(9) PU, single administration) to six healthy individuals. AdGVVEGF121.10 (carrying the human vascular endothelial growth factor 121 cDNA) was administered (4 x 10(8) to 4 x 10(9.5) PU, single administration) directly to the myocardium of 11 individuals with ischemic heart disease. Ad vector administration to the airways of individuals with CF evoked no or minimal serum neutralizing antibodies, even with repetitive administration. In contrast, intratumor administration of an Ad vector to individuals with metastatic colon cancer resulted in a robust antibody response, with anti-Ad neutralizing antibody titers of 10(2) to >10(4). Healthy individuals responded to single intradermal Ad vector variably, from induction of no neutralizing anti-Ad antibodies to titers of 5 x 10(3). Likewise, individuals with ischemic heart disease had a variable response to single intramyocardial vector administration, ranging from minimal neutralizing antibody levels to titers of 10(4). Evaluation of the data from all trials showed no correlation between the peak serum neutralizing anti-Ad response and the dose of Ad vector administered (P > 0.1, all comparisons). In contrast, there was a striking correlation between the peak anti-Ad5 neutralizing antibody levels evoked by vector administration and the level of preexisting anti-Ad5 antibodies (P = 0.0001). Thus, unlike the case for experimental animals, administration of Ad vectors to humans does not invariably evoke a systemic anti-Ad neutralizing antibody response. In humans, the extent of the response is dictated by preexisting antibody titers and modified by route of administration but is not dose dependent. Since the extent of anti-Ad neutralizing antibodies will likely modify the efficacy of administration of Ad vectors, these observations are of fundamental importance in designing human gene therapy trials and in interpreting the efficacy of Ad vector-mediated gene transfer.

Immunonutrition: the role of arginine

Clearly, arginine has great potential as an immunomodulator and may prove useful in catabolic conditions such as severe sepsis and postoperative stress. there is a body of evidence suggesting that supplemental arginine upregulates immune function and reduces the incidence of postoperative infection. More modest improvements in nitrogen balance have been observed. Tumor response to arginine appears to depend on the immunogenicity of the particular tumor and on the requirement of arginine by the tumor as a growth substrate. Of note, ornithine shares the thymotrophic, immunostimulatory and secretagogue effects of arginine. It is, therefore, likely that these compounds share the same cellular mechanism of action or that arginine acts via increasing the concentration of available ornithine. The role of arginine in the injured patient and in the tumor-bearing host demands additional study based on the promising experimental evidence regarding the supplemental use of arginine.

Nutritional support of the cancer patient

Malnutrition, a common problem in cancer patients, adversely affects survival and quality of life. It results from several factors that alter nutritional intake and cause massive metabolic disturbances. Anticancer therapies may compound the malnutrition. Optimal nutrition improves therapeutic modalities and the clinical course and outcome. Oral nutrition should be used whenever possible; in patients unable to ingest adequate amounts orally, enteral and parenteral feedings are safe and effective.

In vivo adenoviral-mediated gene transfer in the treatment of pancreatic cancer

Gene therapy may allow targeted delivery of tumoricidal drugs to treat pancreatic cancer. Cytosine deaminase (CD) is a bacterial enzyme that converts the nontoxic agent 5-fluorocytosine (5FC) to the active chemotherapeutic agent 5-fluorouracil (5FU). Neoplastic cells induced to express the CD gene treated with 5FC may generate locally high concentrations of 5FU while minimising systemic toxicity. Replication deficient adenovirus vector carrying the CD gene (AdCMV.CD) was tested for therapeutic efficacy against the murine pancreatic carcinoma cell line Pan02. Pan02 cells were infected in vitro with AdCMV.CD or null vector (Ad.-Null) and were examined for expression of CD messenger RNA (mRNA) (Northern blot) and CD enzymatic function (spectrophotometry). mRNA transcripts of the CD gene increased in a dose-dependent manner after infection with AdCMV.CD. Conversion of 5FC to 5FU at a multiplicity of infection (MOI) of 20 was measured to be 51% after a 48-hr incubation. Growth inhibition was measured by MTT assay and thymidine uptake. Pan02 growth in vitro treated with AdCMV.CD and 5FC was inhibited by 80% as compared to cells treated with Ad.Null and 5FC. An in vivo model of pancreatic cancer was established by injecting 2.5 x 10(5) PAN02 cells subcutaneously into the flanks of C57BL/ 6 mice. Seven days later AdCMV.CD was injected into each tumor and 5FC was administered for 10 days. Treatment of mice with AdCMV.CD and 5FC inhibited tumor growth compared to mice who received AdCMV.CD only or 5FC only. These data demonstrate the therapeutic efficacy of an enzyme prodrug strategy in experimental pancreatic cancer.

Elevation of intracellular cyclic adenosine monophosphate inhibits the epidermal growth factor signal transduction pathway and cellular growth in pancreatic adenocarcinoma cell lines

BACKGROUND

The epidermal growth factor (EGF) signal transduction pathway, frequently activated in pancreatic cancer, is an important regulator of cellular growth and transformation. This study examined whether activation of the cyclic adenosine monophosphate protein kinase A pathway may inhibit the EGF signal transduction pathway in pancreatic cancer cell lines.

METHODS

Human pancreatic cancer lines BxPC-3 and AsPC-1 were stimulated with EGF, forskolin, or both. Forskolin is a compound that increases cyclic adenosine monophosphate levels. Assays of cell lines were then obtained for cellular growth (MTT assay), anchorage-independent growth (soft agar), and EGF-induced mitogen-activated protein kinase activation as measured by an in-gel kinase assay.

RESULTS

Treatment with forskolin resulted in inhibition of EGF-induced activation of mitogen-activated protein kinase activity (BxPC-3 78% inhibition and AsPC-1 70% inhibition, p < 0.005), diminished cellular proliferation (BxPC-3 92% inhibition and AsPC-1 86% inhibition, p < 0.001), and formation of colonies in soft agar (BxPC-3 98% inhibition and AsPC-1 76% inhibition, p < 0.001). Forskolin did not inhibit EGF receptor autophosphorylation or tyrosine kinase signaling in response to EGF.

CONCLUSIONS

Forskolin-induced inhibition of mitogen-activated protein kinase is associated with diminished pancreatic cancer cell proliferation in vitro. Use of strategies to increase cyclic adenosine monophosphate levels may have therapeutic application in pancreatic cancer.

Relation of perioperative deaths to hospital volume among patients undergoing pancreatic resection for malignancy

OBJECTIVE

The authors examined the effect of hospital and surgeon volume on perioperative mortality rates after pancreatic resection for the treatment of pancreatic cancer.

METHODS

Discharge abstracts from 1972 patients who had undergone pancreaticoduodenectomy or total pancreatectomy for malignancy in New York State between 1984 and 1991 were obtained from the Statewide Planning and Research Cooperative System. Logistic regression analysis was used to determine the relationship between hospital and surgeon experience to perioperative outcome.

RESULTS

More than 75% of patients underwent resection at minimal-volume (fewer than 10 cases) or low-volume (10-50 cases) centers (defined as hospitals in which a minimal number of resections were performed in a given year), and these hospitals represented 98% of the institutions treating peripancreatic cancer. The two high-volume hospitals (more than 81 cases) demonstrated a significantly lower perioperative mortality rate (4.0%) compared with the minimal- (21.8%) and low-volume (12.3%) hospitals (p < 0.001). The perioperative mortality rate was 15.5% for low-volume (fewer than 9 cases) surgeons (defined as surgeons who had performed a minimal number of resections in any hospital in a given year) (n = 687) compared with 4.7% for high-volume (more than 41 cases) pancreatic surgeons (n = 4) (p < 0.001). Logistic regression analysis demonstrated that perioperative death is significantly (p < 0.05) related to hospital volume, but the surgeon's experience is not significantly related to perioperative deaths when hospital volume is controlled.

CONCLUSIONS

These data support a defined minimum hospital experience for elective pancreatectomy for malignancy to minimize perioperative deaths.

Carcinoma of the esophagus. Prognostic significance of histologic type

Previous investigators have reported that in patients with esophageal carcinoma tumor cell type affects prognosis. A retrospective analysis of 258 patients, from 1985 to 1991, undergoing curative esophagogastrectomy for adenocarcinoma (n = 134) or squamous cell carcinoma (n = 124) was performed to test the hypothesis that histologic cell type is an independent prognostic factor and to identify other predictors of survival after resection. The actuarial overall survival (p = 0.16) and disease-specific survival (p = 0.68) were similar for adenocarcinoma (median overall survival = 27 months) and squamous cell carcinoma (median overall survival = 22 months). Univariate analysis identified T stage, N stage, number of diseased nodes, tumor differentiation, tumor site, and blood transfusions as significant (p < 0.05) variables in predicting overall survival. The presence of Barrett's esophagus was not predictive of survival. Multivariate analysis demonstrated that T stage (p = 0.006), N stage (p = 0.01), and number of diseased lymph nodes (p = 0.03) were independent predictors of overall survival. This analysis demonstrated that histologic type is not an independent variable for overall survival in patients undergoing curative esophagogastrectomy for carcinoma of the esophagus and gastroesophageal junction. Outcome is most strongly influenced by extent of disease defined by T and N stage.

Esophageal carcinoma. The unusual variants

The clinical behavior and response to therapy of rare histologic variants of esophageal carcinoma are unclear. To evaluate the results of therapy in this group the records of 29 patients treated between 1949 and 1991 with primary rare histologic variants of esophageal carcinoma were retrospectively reviewed. This group represented 1.2% of 2454 cases of esophageal carcinoma treated between 1949 and 1991 and included mucoepidermoid (n = 14), small-cell (n = 12), adenoid cystic (n = 2), and carcinosarcoma (n = 1) carcinomas. Treatment for localized disease consisted of esophagectomy in five of seven patients with mucoepidermoid carcinoma, two of six patients with small-cell carcinoma, two of two patients with adenoid cystic carcinoma, and one of one patient with carcinosarcoma. Patients with stage IV mucoepidermoid carcinoma were treated predominately with radiation therapy (5/7). The majority of small cell carcinomas were treated with multiagent chemotherapy (10/12). The 1- and 3-year disease-specific survivals were 54% and 9% for mucoepidermoid carcinoma (median survival, 5 months) and 16% and 0% for small-cell carcinoma (median survival, 7 months), respectively. Patients with stage III mucoepidermoid carcinoma (median survival, 20.5 months) compared with those with stage III small-cell carcinoma (median survival, 6.2 months) had a significantly longer duration of survival (p < 0.05). Distant disease was present in 86% of patients in whom recurrence developed after esophagectomy Esophagectomy is standard therapy for localized carcinomas of the esophagus. Small-cell carcinoma appears to be a more aggressive variant of carcinoma and is most commonly treated with chemotherapy.

Infrageniculate bypass graft entrapment

When failure of vein grafts is due to technical error it is usually observed in the early postoperative period. In this review we describe late failure of five bypass grafts as a result of entrapment of the vein graft caused by an improperly placed tunnel from the femoral to the popliteal artery. Vein graft entrapment may either produce no symptoms or eventually lead to limb ischemia. Pulses and pressures that vary with flexion and extension maneuvers should alert the clinician to the possibility of an entrapment syndrome. The characteristic arteriographic findings observed in these patients include an aberrant course of the vein graft outside the anatomic course of the popliteal artery and position-dependent compression of the graft. The ability of magnetic resonance angiography to demonstrate the arteriographic appearance of the graft as well as the precise location of the compression and to identify structures involved in the entrapment, make it a valuable noninvasive tool in the preoperative assessment of these patients. Treatment options include division of the gastrocnemius muscle, division of the vein graft, or replacement of the vein graft. Familiarity with vein graft entrapment should facilitate its recognition. Careful placement of bypass grafts along the anatomic course of the popliteal artery within the popliteal space will prevent this complication.

Enteral nutrition with supplemental arginine, RNA, and omega-3 fatty acids in patients after operation: immunologic, metabolic, and clinical outcome

The individual nutrients arginine, RNA, and omega-3 fatty acids improve immune function, but prospective trials have not demonstrated their effects on clinical outcome. Patients (n = 85) who underwent operation for upper gastrointestinal malignancies were randomized to receive the supplemental diet or a standard enteral diet after surgery. Clinical patient characteristics were similar between the two groups. Mean caloric intakes (1421 vs 1285 kcal/day) were similar between groups. Mean nitrogen intakes (15.6 vs 9.0 gm/day) and nitrogen balances (-2.2 vs -6.6 gm/day) measured in the first 20 patients were significantly greater in the supplemented group than in the standard group (p = 0.05). In vitro lymphocyte mitogenesis was measured in the first 31 patients and was decreased on postoperative day 1 in both groups, but normal levels were regained only in the supplemented group. In the cohort of 77 eligible patients, infectious and wound complications occurred significantly less often (11% vs 37%) in the supplemented group than in the standard group (p = 0.02). Linear logistic models for infectious/wound complications with control for the amount of nitrogen suggested (p = 0.10) dietary treatment as the major factor. Mean length of stay in the hospital was significantly shorter (p = 0.01) for the supplemented group (15.8 +/- 5.1 days) than for the standard group (20.2 +/- 9.4 days). These results suggest that postoperative enteral nutrition with supplemental arginine, RNA, and omega-3 fatty acids instead of a standard enteral diet significantly improved immunologic, metabolic, and clinical outcomes in patients with upper gastrointestinal malignancies who were undergoing major elective surgery.

Enhancement of interleukin-2 immunotherapy with L-arginine

Nutrient substrates have been shown to enhance cell-mediated immunity, but their role as adjuvants to immunotherapy has not been previously determined. This study evaluated L-arginine as an essential substrate for optimal generation of lymphokine-activated killer (LAK) cells. This experiment also assessed supplemental dietary L-arginine as a means to potentiate the host antitumor response to interleukin-2 (IL-2) in a murine neuroblastoma (NRB) model. A/J mice received 1% arginine or isonitrogenous 1.7% glycine in addition to a regular diet 14 days before subcutaneous inoculation with C1300 NRB cells. Twenty-four hours later, animals received low (1 x 10(6) U/kg three times a day) or high (3 x 10(6) U/kg three times a day) doses of IL-2 or saline intraperitoneally for 4 days. On days 4 and 10 post-C1300 NRB inoculation, mice were killed for assessment of natural killer cell and tumor specific cytotoxicity. Remaining animals were followed for tumor incidence, tumor growth, and duration of host survival. Interleukin-2 therapy in mice receiving dietary arginine compared with those receiving glycine resulted in significantly augmented natural killer cell cytotoxicity (day 4) and generation of specific tumoricidal mechanisms (day 10). The addition of dietary arginine to low-dose IL-2 therapy significantly diminished C1300 NRB engraftment (p less than 0.05) and growth (p less than 0.001) and prolonged the duration of host survival (p less than 0.05) compared with the glycine treatment group. In vitro studies demonstrated that L-arginine is an essential substrate for optimal generation of LAK cells. Thus, supplemental dietary L-arginine enhances lymphocyte cytotoxic mechanisms and potentiates IL-2 immunotherapy.

Nutritional support of patients with cancer of the gastrointestinal tract

Malnutrition is extremely common in patients with malignant disease. Whereas the causes are multifactorial, the predominant factor is the imbalance between nutrient intake and host nutrient requirements. Furthermore, the evidence suggests that cachexia is related to abnormal changes in host intermediary metabolism induced by host-tumor interactions, and endogenous peptides such as TNF may be important mediators. The role of nutritional therapy in cancer patients remains to be defined. Clearly, patients with severe malnutrition benefit from nutritional intervention. However, the benefit of nutritional therapy in less severe cases of malnutrition as an adjuvant to oncologic therapy has yet to be established.

Dietary manipulation of methotrexate-induced enterocolitis

Administration of chemotherapy is limited by host toxicity, which is often manifested by severe enterocolitis. This study evaluated the effects of a liquid, elemental, chemically defined diet (ED) supplemented with 2% glutamine (Glu-ED) compared with a polypeptide diet (PPD) on the morbidity and mortality after methotrexate (MTX) administration. Fischer 344 rats (n = 80) were fed either a regular rat chow diet (RD), a 2% glycine supplemented elemental diet (Gly-ED), a 2% glutamine-supplemented elemental diet (GLU-ED), and a glycine-supplemented polypeptide diet(Gly-PPD) for 7 days prior to administration of MTX (20 mg/kg, ip). After 72 hours, eight rats per group were killed; portal vein and vena cava blood, mesenteric lymph nodes (MLN), liver, small intestine, and cecum were sampled for bacterial culture. Remaining animals were followed to calculate survival. One hundred percent of the Gly-PPD and 25% of the Glu-ED animals survived compared with 0% of the Gly-ED animals. Our data showed that ED resulted in an increased quantity of intestinal Gram-negative bacteria and diminished intestinal mucosal height and mucosal DNA/protein content. The polypeptide diet prevented intestinal mucosal atrophy, avoided MTX-induced enterocolitis and significantly improved animal survival compared with an elemental diet with or without glutamine supplementation.

Natural killer cell stimulatory factor (NKSF) augments natural killer cell and antibody-dependent tumoricidal response against colon carcinoma cell lines

The therapy of colorectal cancer may be improved by biologic response modifiers that enhance natural killer (NK) cell and antibody-dependent tumoricidal mechanisms. This study examined the effect of a recently discovered cytokine purified from the supernatant of an Ebstein-Barr virus-transformed B-lymphoblastoid cell line (RPMI-8866), natural killer cell stimulatory factor (NKSF), on NK and antibody-dependent cellular cytotoxicity (ADCC) of human colon adenocarcinoma cell lines. Human peripheral blood lymphocytes were cultured for 24 hr in the presence or absence of NKSF (3.6 pM) or interleukin-2 (1 nM). The cultured lymphocytes were analyzed for lytic potential toward chromium-51-labeled colon carcinoma targets SW 1116, 498 LI, and WC 1. ADCC was measured by incubating chromium-51-labeled SW 1116 or WC 1 targets with the monoclonal antibody CO17-1A, an IgG2a antibody reactive with gastrointestinal cancer-associated cell antigen, or control mouse IgG prior to testing NKSF-treated or control PBL effectors in a 6-hr cytotoxicity assay. NKSF significantly enhanced NK cytolysis of colon carcinoma and NK-resistant lymphoma cell lines, and on a molar basis was approximately 300 times more potent than interleukin-2 in generating NK cytotoxicity. Furthermore, NKSF significantly augmented lymphocyte-mediated ADCC against colon carcinoma targets, and the combination of NKSF with the antibody CO17-1A had an additive effect on lymphocyte tumoricidial capacity. Thus, NKSF may have a potential role in the treatment of colon cancer.

Low-dose interferon gamma renders neuroblastoma more susceptible to interleukin-2 immunotherapy

Neuroblastoma remains a common and deadly childhood tumor, resistant to both surgical and chemo/radiotherapeutic intervention in its advanced stages. The role of immunotherapy in such cancers has yet to be defined. In previous work, we found that the addition of interferon gamma (IFN-gamma) to 3-day in vitro tissue cultures of the murine neuroblastoma C1300, led not only to the tumor's increased cell surface expression of the immunologically important major histocompatibility complex (MHC) class I antigen, but also to an increased susceptibility of such modified tumor to subsequent lymphokine activated killer (LAK) cell lysis. In this study, we sought to determine the in vivo applicability of these findings. Initial dose-response studies helped define a regimen of rIFN-gamma's administration that upregulated MHC class I without activating host natural killer (NK) activity. A/J mice bearing 7-day-old subcutaneous C1300 were randomized to receive daily morning injections of either 0, 25,000, 50,000, or 100,000 U of rIFN-gamma intraperitoneally for 6 days. Animals were killed at days 3, 6, and 9 after initiation of rIFN-gamma therapy, and tumors were excised, digested, and stained for both MHC class I and II expression. At the time of sacrifice, splenocytes from each animal were tested for NK cytotoxicity toward YAC (an NK-sensitive lymphoma) and C1300. These studies defined 3 days of therapy with 25,000 U as a "priming" dose that increased expression of class I with minimal impact on NK activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired macrophage function in severe protein-energy malnutrition

Protein-energy malnutrition induces immunosuppression that predisposes to sepsis, but the mechanisms are unclear. This study examines the role of the macrophage in host defense in the malnourished state. Swiss-Webster mice (N = 300) were randomly allocated to control (24% casein) or low-protein (2.5% casein) diets for 8 weeks. We studied the ability of two populations of macrophages, peritoneal macrophages, and Kupffer cells to produce superoxide anion after in vivo administration of endotoxin or mycobacterium (bacille Calmette-Guérin). Phorbol diester and Candida albicans were used as stimuli. In another group of mice, we evaluated the ability of interferon gamma to up-regulate superoxide anion release and Candida phagocytosis and killing. Mice under protein-energy malnutrition demonstrated decreased mean body weights, serum protein levels, and cell yields. Superoxide anion production in resident and activated (lipopolysaccharide, interferon gamma, bacille Calmette-Guérin infection) peritoneal macrophages was significantly reduced in the malnourished group. Candida phagocytosis and killing were also both depressed in malnourished mice. Kupffer cells failed to generate superoxide anion in all groups. We conclude that severe protein-energy malnutrition significantly impairs macrophage function, which could diminish response to acute and chronic septic challenges. Interferon gamma up regulated peritoneal macrophage and Kupffer cell microbicidal function, which suggests a therapeutic role for this lymphokine in the malnourished septic host.

Comparison of acute and chronic protein-energy malnutrition on host antitumor immune mechanisms

Protein-calorie malnutrition (PCM) is prevalent in cancer patients. However, the effect of PCM on anti-tumor immunity is unclear and critically important in an era of improving results with adoptive immunotherapy. This study examined the effect of short- and long-term PCM on tumor-specific and natural immune effector mechanisms in a murine neuroblastoma (C1300 NRB) model. A/J mice received an isocaloric 2.5% or 24% casein diet for 3 or 8 weeks before inoculation with tumor. Three weeks later lymphocytes from tumor-bearing mice were harvested for determination of cytotoxic T lymphocyte (CTL) generation and natural killer (NK) cell cytotoxicity. Both 3 and 8 weeks of PCM significantly reduced mean total body weight by 25% (p less than 0.001) and 41% (p less than 0.001), respectively, compared with regularly nourished mice. Short-term PCM did not inhibit CTL or NK cytotoxicity, whereas long-term PCM significantly diminished CTL generation (p less than 0.001) but preserved NK cytotoxic function. These results indicate that CTL development against autologous tumor, in contrast to basal NK function, is dependent on host nutritional status. Mean tumor growth, determined by tumor-weight to carcass-weight ratio, was unchanged for both short- and long-term protein-energy deprived groups compared with results in regularly nourished mice. These findings suggest that NK function is the predominant effector mechanism inhibiting C1300 NRB growth and that NK tumoricidal capacity is preserved during PCM.

Protein-calorie malnutrition inhibits antitumor response to interleukin-2 immunotherapy

The efficacy of systemic interleukin-2 (IL-2) immunotherapy is dependent on a competent host immune response. This study demonstrated that protein-calorie malnutrition (PCM) inhibited the generation of an antitumor response to IL-2. A/J mice received an isocaloric diet of 2.5% or 24% casein 8 weeks before inoculation with C1300 neuroblastoma cells. Three weeks later lymphocytes from tumor-bearing mice were harvested for determination of cytotoxic T-lymphocyte generation and natural killer cell cytotoxicity. PCM produced a significant reduction in total body weight (p less than 0.001) and serum albumin concentration (p less than 0.001). PCM inhibited generation of cytotoxic T lymphocytes (p less than 0.001), T-lymphocyte response in mixed lymphocyte reaction (p less than 0.001), and in vitro activation of natural killer cell cytotoxicity with IL-2 (p less than 0.001). A second experiment was performed to evaluate whether the in vitro deficits in tumor-specific and natural immunity in the animal model of PCM would diminish the efficacy of systemic high-dose IL-2 (3 x 10(6) units/kg three times daily for 5 days). The mean percent inhibition of C1300 growth with IL-2 was only 15% in mice with PCM compared with 60% in well-nourished mice (p less than 0.01). Median host survival time was greater in well-nourished animals (55 days) compared with animals with PCM (39 days) that received IL-2 (p less than 0.05). These data suggest that nutritional status is a critically important variable in tumoricidal response to systemic IL-2.

Transfusion-induced immunosuppression results in diminished host survival in a murine neuroblastoma model

Perioperative blood transfusion has been associated with decreased survival in cancer patients. The immunologic consequences of H-2 incompatible blood transfusion as related to neoplasia are unclear. This report examined the effect of multiple allogeneic blood transfusions, compared to syngeneic transfusions and saline infusion, on cellular immunity, tumor growth, and host survival in a murine C1300 neuroblastoma model. A/J mice were randomized to receive two weekly transfusions of washed whole blood cells from C57 Bl/6 or A/J donors or saline. Animals transfused with allogeneic blood, compared to syngeneic transfusions or saline infusions, had a significantly diminished lymphocyte response to mitogen (P less than 0.001), reduced donor-specific (P less than 0.001) and third party alloantigen (P less than 0.01) MLR, and reduced cytotoxicity against a natural killer (NK) cell-sensitive target (P less than 0.001). These in vitro deficits in cellular immunity correlated with a significantly greater Day 21 tumor weight to total body weight ratio in the allogeneic group (0.33) compared with the syngeneic (0.25) and saline (0.28) groups P less than 0.05). Median host survival was reduced in the allogeneic group (24 days) compared with the syngeneic (30 days) and saline (31 days) groups. There were no significant differences in cellular immunity, tumor growth, or survival between syngeneic and saline control groups. Allogeneic blood transfusion had an adverse affect on NK and T-lymphocyte function which was associated with enhanced tumor growth and reduced survival in tumor-bearing mice.

Tumor immunization. Improved results after vaccine modified with recombinant interferon gamma

The purpose of this study was to determine if a 3-day in vitro culture of the murine neuroblastoma C1300 with 500 U/mL of recombinant interferon gamma resulted in a protective crossreactivity to parent C1300. Twenty A/J mice received either a vaccine of 1 x 10(6) irradiated C1300 tumor cells intradermally or an equivalent inoculum of C1300 that had been incubated in recombinant interferon gamma (C1300*). One week later, all animals were rechallenged with 1 x 10(6) viable C1300. Animals immunized with C1300* had a significantly delayed early tumor incidence that translated into a survival advantage for the group. At the time of tumor rechallenge, a significantly increased level of nonspecific systemic immunity was conferred by the C1300* immunization. Thus, modification of tumor with recombinant interferon gamma before introduction as a vaccine may improve that vaccine's protective capability.