Vaccination with helper-dependent adenovirus enhances the generation of transgene-specific CTL

Recombinant adenoviral vectors (AdV) have been used experimentally as vaccines to present antigenic transgenes in vivo. However, administration of first-generation vectors (FG-AdV) is often limited by their induction of antiviral immunity. To address this limitation, helper-dependent vectors (HD-AdV) were developed that lack viral coding regions. While the administration of HD-AdV results in long-term gene expression in vivo, their utility as immunogens has never been examined. Direct vaccination with 10(8) blue-forming units (BFU) of HD-AdV injected into C57BL/6 mice lead to superior transgene-specific CTL and antibody responses when compared to the same amount of a FG-AdV. The antibody responses to viral antigens were high in response to both the vectors. As a mechanism to reduce viral exposure, dendritic cells (DC) were transduced with HD-AdV in vitro and then used as a cell-based vaccine. DC transduced with HD-AdV expressed higher levels of transgene-specific mRNA and up to 1200-fold higher levels of transgene protein than did DC transduced with a FG-AdV. In addition, HD-AdV-transduced DC stimulated superior transgene-specific CTL responses when administered in vivo, an effect that was further enhanced by maturing the DC with LPS prior to administration. In contrast to direct immunization with HD-AdV, vaccination with HD-AdV-transduced DC was associated with limited antibody responses against the AdV. We conclude that HD-AdV stimulates superior transgene-specific immune responses when compared to a FG-AdV, and that immunization with a DC-based vaccine maintains this efficacy while limiting antiviral reactivity.

Marijuana smoke and Delta(9)-tetrahydrocannabinol promote necrotic cell death but inhibit Fas-mediated apoptosis

Marijuana smoke shares many components in common with tobacco smoke except for the presence of Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychotropic compound found only in Cannibis sativa. Delta(9)-THC has been shown to potentiate smoke-induced oxidative stress and necrotic cell death. In the present study, our objective was to determine the effects of Delta(9)-THC on the balance between Fas-induced apoptosis and necrosis in A549 lung tumor cells. We found that Fas-induced activation of caspase-3 was inhibited by whole smoke from both tobacco and marijuana cigarettes. Gas-phase smoke, which generates high levels of intracellular reactive oxygen species, had no effect on caspase-3 activity. However, particulate-phase smoke (tar) was a potent inhibitor of Fas-induced caspase-3 activity, with marijuana tar being more potent than either tobacco or placebo marijuana tar (lacking Delta(9)-THC). Delta(9)-THC also inhibited Fas-induced caspase-3 activity in A549 cells. In contrast, no inhibition was observed when Delta(9)-THC was incubated with activated caspase-3 enzyme, suggesting that Delta(9)-THC acts on the cell pathway(s) leading to caspase-3 activation and not directly on enzyme function. Flow cytometry was used to measure the percentage of cells undergoing apoptosis (staining for annexin V) versus necrosis (staining for propidium iodide) and confirmed that both marijuana tar extract and synthetic Delta(9)-THC inhibit Fas-induced apoptosis while promoting necrosis. These observations suggest that the Delta(9)-THC contained in marijuana smoke disrupts elements of the apoptotic pathway, thereby shifting the balance between apoptotic and necrotic cell death. This shift may affect both the carcinogenic and immunologic consequences of marijuana smoke exposure.

Induction and regulation of the carcinogen-metabolizing enzyme CYP1A1 by marijuana smoke and delta (9)-tetrahydrocannabinol

Induction of the carcinogen-metabolizing enzyme cytochrome P4501A1 (CYP1A1) is a key step in the development of tobacco-related cancers. To determine if marijuana smoke activates CYP1A1, a murine hepatoma cell line expressing an inducible CYP1A1 gene (Hepa-1) was exposed in vitro to tar extracts prepared from either tobacco, marijuana, or placebo marijuana cigarettes. Marijuana tar induced higher levels of CYP1A1 messenger RNA (mRNA) than did tobacco tar, yet resulted in much lower CYP1A1 enzyme activity. These differences between marijuana and tobacco were primarily due to Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychoactive component of marijuana. Here we show that Delta(9)-THC acts through the aryl hydrocarbon receptor complex to activate transcription of CYP1A1. A 2-microg/ml concentration of Delta(9)-THC produced an average 2.5-fold induction of CYP1A1 mRNA, whereas a 10- microg/ml concentration of Delta(9)-THC produced a 4.3-fold induction. No induction was observed in Hepa-1 mutants lacking functional aryl-hydrocarbon receptor or aryl-hydrocarbon receptor nuclear translocator genes. At the same time, Delta(9)-THC competitively inhibited the CYP1A1 enzyme, reducing its ability to metabolize other substrates. Spiking tobacco tar with Delta(9)-THC resulted in a dose-dependent decrease in the ability to generate CYP1A1 enzyme activity as measured by the ethoxyresorufin-o-deethylase (EROD) assay. This inhibitory effect was confirmed by Michaelis-Menton kinetic analyses using recombinant human CYP1A1 enzyme expressed in insect microsomes. This complex regulation of CYP1A1 by marijuana smoke and the Delta(9)-THC that it contains has implications for the role of marijuana as a cancer risk factor.

Microbial lipopeptides stimulate dendritic cell maturation via Toll-like receptor 2

The ability of dendritic cells (DC) to initiate immune responses in naive T cells is dependent upon a maturation process that allows the cells to develop their potent Ag-presenting capacity. Although immature DC can be derived in vitro by treatment of peripheral blood monocytes with GM-CSF and IL-4, additional signals such as those provided by TNF-alpha, CD40 ligand, or LPS are required for complete maturation and maximum APC function. Because we recently found that microbial lipoproteins can activate monocytes and DC through Toll-like receptor (TLR) 2, we also investigated whether lipoproteins can drive DC maturation. Immature DC were cultured with or without lipoproteins and were monitored for expression of cell surface markers indicative of maturation. Stimulation with lipopeptides increased expression of CD83, MHC class II, CD80, CD86, CD54, and CD58, and decreased CD32 expression and endocytic activity; these lipopeptide-matured DC also displayed enhanced T cell stimulatory capacity in MLR, as measured by T cell proliferation and IFN-gamma secretion. The lipid moiety of the lipopeptide was found to be essential for induction of maturation. Preincubation of maturing DC with an anti-TLR2 blocking Ab before addition of lipopeptide blocked the phenotypic and functional changes associated with DC maturation. These results demonstrate that lipopeptides can stimulate DC maturation via TLR2, providing a mechanism by which products of bacteria can participate in the initiation of an immune response.

Activation of toll-like receptor 2 on human dendritic cells triggers induction of IL-12, but not IL-10

Mammalian Toll-like receptors (TLRs) are required for cell activation by bacterial lipoproteins (bLP) and LPS. Stimulation of monocytes with bLP and LPS results in a TLR-dependent induction of immunomodulatory genes leading to the production of pro-inflammatory cytokines. In this paper, we compared the expression and response of TLRs on monocytes and dendritic cells (DC). TLR2, but not TLR4, was detected on peripheral blood monocytes and DC, in lymphoid tissue CD1alpha+ DC as well as on in vitro monocyte-derived DC. Upon stimulation with bLP or LPS, monocytes produced IL-12 and IL-10 at similar levels, whereas monocyte-derived DC produced comparable levels of IL-12, but little IL-10. Greater than 90% of the bLP-induced production of IL-12 was blocked by anti-TLR2 mAb. Thus, DC express TLR2 and activation of this receptor by bLP provides an innate mechanism by which microbial pathogens preferentially activate cell-mediated immunity.

Delta-9-tetrahydrocannabinol inhibits antitumor immunity by a CB2 receptor-mediated, cytokine-dependent pathway

In this study, we show that Delta-9-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, suppresses host immune reactivity against lung cancer. In two different weakly immunogenic murine lung cancer models, intermittent administration of THC (5 mg/kg, four times/wk i.p. for 4 wk) led to accelerated growth of tumor implants compared with treatment with diluent alone. In contrast to our findings in immunocompetent mice, THC did not affect tumor growth in tumor-bearing SCID mice. The immune inhibitory cytokines, IL-10 and TGF-beta, were augmented, while IFN-gamma was down-regulated at both the tumor site and in the spleens of THC-treated mice. Administration of either anti-IL-10- or anti-TGF-beta-neutralizing Abs prevented the THC-induced enhancement in tumor growth. Both APC and T cells from THC-treated mice showed limited capacities to generate alloreactivity. Furthermore, lymphocytes from THC-treated mice transferred the effect to normal mice, resulting in accelerated tumor growth similar to that seen in the THC-treated mice. THC decreased tumor immunogenicity, as indicated by the limited capacity for tumor-immunized, THC-treated mice to withstand tumor rechallenge. In vivo administration of a specific antagonist of the CB2 cannabinoid receptor also blocked the effects of THC. Our findings suggest the THC promotes tumor growth by inhibiting antitumor immunity by a CB2 receptor-mediated, cytokine-dependent pathway.

Granulocyte macrophage colony-stimulating factor and interleukin 4 enhance the number and antigen-presenting activity of circulating CD14+ and CD83+ cells in cancer patients

Antigen-presenting cells (APCs) are essential for stimulating antigen-specific immunity, including immunity against tumor cells. We hypothesized that systemic administration of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4, which promote monocytes to differentiate into dendritic cells in vitro, might enhance the number and antigen-presenting activity of CD14+ cells in vivo. Patients with metastatic solid malignancies were treated with daily s.c. injections of either GM-CSF alone (2.5 microg/kg/day) or GM-CSF in combination with IL-4 (0.5-6.0 microg/kg/day) in a multicohort study. When given alone, GM-CSF increased the number of CD14+ cells but did not enhance the cells' expression of APC markers or antigen-presenting activity. In contrast, combination therapy with GM-CSF and IL-4 stimulated CD14+ cells to acquire several APC characteristics including increased expression of HLA-DR and CD11c, decreased CD14, increased endocytotic activity, and the ability to stimulate T cells in a mixed leukocyte reaction. Combination therapy also induced a dose-dependent increase in the number of CD14-/CD83+ cells with APC activity. Clinically significant and sustained tumor regression was observed in one patient. Systemic therapy with GM-CSF and IL-4 may provide a mechanism for increasing the number and function of APCs in patients with cancer.

Tumors promote altered maturation and early apoptosis of monocyte-derived dendritic cells

Tumors produce a number of immunosuppressive factors that block the maturation of CD34+ stem cells into dendritic cells (DC). We hypothesized that tumors might also interfere with the maturation and/or function of human monocyte-derived DC. In contrast to stem cells, we found that CD14+ cells responded to tumor culture supernatant (TSN) by increasing expression of APC surface markers, up-regulating nuclear translocation of RelB, and developing allostimulatory activity. Although displaying these characteristics of mature DC, TSN-exposed DC lacked the capacity to produce IL-12, did not acquire full allostimulatory activity, and rapidly underwent apoptosis. The effects of TSN appeared to be specific for maturing DC, and were not reversed by Abs against known DC regulatory factors including IL-10, vascular endothelial growth factor, TGF-beta, or PGE2. Supernatants collected from nonmalignant cell sources had no effect on DC maturation. The altered maturation and early apoptosis of monocyte-derived DC may represent another mechanism by which tumors evade immune detection.

Oxidative stress produced by marijuana smoke. An adverse effect enhanced by cannabinoids

Marijuana (MJ) smoking produces inflammation, edema, and cell injury in the tracheobronchial mucosa of smokers and may be a risk factor for lung cancer. Because oxidative stress may mediate some of these effects, this study was designed to test the hypothesis that cannabinoids in MJ smoke contribute to cellular oxidative stress. Oxidative stress was evaluated in an endothelial cell line (ECV 304) following exposure to smoke produced from MJ cigarettes containing either 0, 1.77, or 3.95% Delta9-tetrahydrocannabinol (Delta9-THC). Brief exposure to smoke from 3.95% MJ cigarettes stimulated the formation of reactive oxygen species (ROS) by 80% over control levels and lowered intracellular glutathione levels by 81%. Smoke-induced ROS generation increased in a dose- and time-dependent manner. In contrast, exposure to smoke from MJ containing 0% Delta9-THC produced no increase in ROS despite a 70% decline in glutathione levels. Smoke from MJ containing 1.77% Delta9-THC stimulated intermediate levels of ROS. A brief, 30-min exposure to MJ smoke, regardless of the Delta9-THC content, also induced necrotic cell death that increased steadily up to 48 h of observation. MJ smoke passed through a Cambridge filter that removed particulate matter was 3.4-fold more active in ROS production compared with unfiltered smoke, suggesting that most of the oxidative effects are produced by the gaseous phase. Alveolar macrophages obtained from habitual MJ smokers displayed low levels of glutathione compared with macrophages from nonsmokers. We conclude that MJ smoke containing Delta9-THC is a potent source of cellular oxidative stress that could contribute significantly to cell injury and dysfunction in the lungs of smokers.

Presentation of renal tumor antigens by human dendritic cells activates tumor-infiltrating lymphocytes against autologous tumor: implications for live kidney cancer vaccines

The clinical impact of dendritic cells (DCs) in the treatment of human cancer depends on their unique role as the most potent antigen-presenting cells that are capable of priming an antitumor T-cell response. Here, we demonstrate that functional DCs can be generated from peripheral blood of patients with metastatic renal cell carcinoma (RCC) by culture of monocytes/macrophages (CD14+) in autologous serum containing medium (RPMI) in the presence of granulocyte macrophage colony-stimulating factor and interleukin (IL) 4. For testing the capability of RCC-antigen uptake and processing, we loaded these DCs with autologous tumor lysate (TuLy) using liposomes, after which cytometric analysis of the DCs revealed a markedly increased expression of HLA class I antigen and a persistent high expression of class II. The immunogenicity of DC-TuLy was further tested in cultures of renal tumor infiltrating lymphocytes (TILs) cultured in low-dose IL-2 (20 Biologic Response Modifier Program units/ml). A synergistic effect of DC-TuLy and IL-2 in stimulating a T cell-dependent immune response was demonstrated by: (a) the increase of growth expansion of TILs (9.4-14.3-fold; day 21); (b) the up-regulation of the CD3+ CD56- TcR+ (both CD4+ and CD8+) cell population; (c) the augmentation of T cell-restricted autologous tumor lysis; and (d) the enhancement of IFN-gamma, tumor necrosis factor-alpha, granulocyte macrophage colony-stimulating factor, and IL-6 mRNA expression by TILs. Taken together, these data implicate that DC-TuLy can activate immunosuppressed TIL via an induction of enhanced antitumor CTL responses associated with production of Thl cells. This indicates a potential role of DC-TuLy vaccines for induction of active immunity in patients with advanced RCC.

Costimulation of naive CD8(+) lymphocytes induces CD4 expression and allows human immunodeficiency virus type 1 infection

Human immunodeficiency virus type 1 (HIV-1) infection requires cell surface expression of CD4. Costimulation of CD8(+)/CD4(-) T lymphocytes by anti-CD3 and anti-CD28 antibodies or by allogeneic dendritic cells induced expression of CD4 and rendered these CD8 cells susceptible to HIV-1 infection. Naive CD45RA+ cells responded with greater expression of CD4 than did CD45RO+ cells. CD8(+) lymphocytes derived from fetal or newborn sources exhibited a greater tendency to express CD4, consistent with their naive states. This mechanism of infection suggests HIV-induced perturbation of the CD8 arm of the immune response and could explain the generally rapid disease progression seen in HIV-infected children.

Interferon-alpha and granulocyte-macrophage colony-stimulating factor differentiate peripheral blood monocytes into potent antigen-presenting cells

The diverse roles of interferon-alpha (IFN-alpha) in regulating the immune response to infectious agents suggested that it might affect dendritic cell (DC) development. Peripheral blood mononuclear cells cultured with IFN-alpha and granulocyte-macrophage colony-stimulating factor (GM-CSF) developed a dendritic morphology and expressed high levels of the class I and II human leukocyte antigens (HLA), B7 co-stimulatory molecules, adhesion proteins, and CD40. Elevated DC expression of B7-2 and HLA-DR was observed with increasing IFN-alpha concentrations up to 5000 U/mL. The effects of IFN-alpha on DC immunophenotype were not reversed by adding neutralizing antibodies against interleukin-4 (IL-4) or tumor necrosis factor alpha to the cell cultures or by eliminating lymphocytes from the cultures. The addition of IFN-alpha to cultures containing optimal concentrations of IL-4 and GM-CSF significantly increased the B7-2 and HLA-DR levels above those present on DCs grown in two cytokines. The DCs generated with IFN-alpha and GM-CSF were potent antigen-presenting cells in allogeneic mixed leukocyte reactions. They also were capable of taking up, processing, and presenting tetanus toxin to autologous T lymphocytes. These results demonstrate an important role for IFN-alpha in the generation of DCs with potent antigen-presenting capabilities from peripheral blood monocytes.

The effect of glucose and glucagon-like peptide-1 stimulation on insulin release in the perfused pancreas in a non-insulin-dependent diabetes mellitus animal model

This study was designed to investigate the effect of glucogon-like peptide-1 (GLP-1) on pancreatic beta-cell function in normal, Zucker diabetic fatty (ZDF) rats, a model for non-insulin-dependent diabetes mellitus (NIDDM or type II diabetes) and their heterozygous siblings. Pancreas perfusion and enzyme-linked immunosorbent assay (ELISA) were used to detect the changes in insulin release under fasting and hyperglycemic conditions and following stimulation with GLP-1. Animals from the ZDF/Gmi-fa rats (ZDF) were grouped according to age, sex, and phenotype (obese or lean), and compared with LA lean rats. Glucose stimulation (10 mmol/L) in obese rats showed repressed response in insulin release. Glucose plus GLP-1 stimulation caused increased insulin release in all groups. The degree of this response differed between groups: lean > obese; young > adult; female > male. The LA lean control group was most sensitive, while the ZDF overtly diabetic group had the lowest response. In addition, the pulsatile pattern of insulin secretion was suppressed in ZDF rats, especially in obese groups. These results support the hypothesis that GLP-1 can effectively stimulate insulin secretion. Insulin release was defective in ZDF obese rats and could be partially restored with GLP-1. ZDF lean rats also showed suppression of beta-cell function and there was a difference in beta-cell function related to sex in ZDF strain. This study documents the efficacy of GLP-1 to stimulate insulin release and contributes to our understanding of the pathophysiological mechanisms underlying NIDDM.

Histopathologic and molecular alterations in bronchial epithelium in habitual smokers of marijuana, cocaine, and/or tobacco

BACKGROUND

Tobacco smoking has been observed to cause molecular alterations in bronchial epithelium that antedate the development of lung carcinoma. The rising prevalence of marijuana and cocaine use among young adults in the United States prompted us to investigate whether similar molecular and histopathologic alterations occur in habitual smokers of marijuana and/or cocaine who may or may not also smoke tobacco.

METHODS

Bronchoscopy was performed in 104 healthy volunteer subjects, including 28 nonsmokers and 76 smokers of one or more of the following substances: marijuana, tobacco, and/or cocaine. Bronchial mucosa biopsy specimens and brushings were analyzed for histopathologic changes, for immunohistopathologic expression of intermediate or surrogate end-point markers that are linked to an increased risk of cancer (Ki-67 [a marker of cell proliferation], epidermal growth factor receptor, p53, Her-2/neu [also known as erbB-2 and ERBB2], globular actin, and abnormal DNA ploidy). Reported P values are two-sided.

RESULTS

Smokers of any one substance or of two or more substances exhibited more alterations than nonsmokers in five to nine of the 10 histopathologic parameters investigated (all P < .05), and they exhibited more molecular abnormalities than nonsmokers. Differences between smokers and nonsmokers were statistically significant (all P < or = .01) for Ki-67, epidermal growth factor receptor, globular actin, and DNA ploidy. There was general agreement between the presence of molecular abnormalities and histopathologic alterations; however, when disagreement occurred, the molecular abnormalities (e.g., Ki-67 and epidermal growth factor receptor) were more frequently altered (all P < or = .01).

CONCLUSIONS

These findings suggest that smoking marijuana and/or cocaine, like tobacco smoking, exerts field cancerization effects on bronchial epithelium, which may place smokers of these substances at increased risk for the subsequent development of lung cancer.

Acute and chronic effects of cocaine on the immune system and the possible link to AIDS

The pathogenesis of AIDS is a complex and prolonged process that is affected by a variety of cofactors, including the abuse of both intravenous and smoked (crack) cocaine. The exact mechanisms by which cocaine facilitates this disease are yet to be proven, but likely include a combination of increased risk due to cocaine-related social behaviours, a wide-ranging capacity for cocaine to suppress the immune system, and an effect of cocaine on the infectivity and replication of HIV. While sometimes contradictory, both human and animal studies document that cocaine alters the function of natural killer (NK) cells, T cells, neutrophils and macrophages, and alters the ability of these cells to secrete immunoregulatory cytokines. In addition to these effects on the immune system, cocaine also enhances the infectivity and/or replication of HIV when tested using human cells in vitro.

Airway inflammation in young marijuana and tobacco smokers

Forty healthy young subjects, ages 20 to 49 yr, underwent videobronchoscopy, mucosal biopsy, and bronchial lavage to evaluate the airway inflammation produced by habitual smoking of marijuana and/or tobacco. Videotapes were graded in a blinded manner for central airway erythema, edema, and airway secretions using a modified visual bronchitis index. The bronchitis index scores were significantly higher in marijuana smokers (MS), tobacco smokers (TS), and in combined marijuana/tobacco smokers (MTS), than in nonsmokers (NS). As a pathologic correlate, mucosal biopsies were evaluated for the presence of vascular hyperplasia, submucosal edema, inflammatory cell infiltrates, and goblet cell hyperplasia. Biopsies were positive for two of these criteria in 97% of all smokers and for three criteria in 72%. By contrast, none of the biopsies from NS exhibited greater than one positive finding. Finally, as a measure of distal airway inflammation, neutrophil counts and interleukin-8 (IL-8) concentrations were determined in bronchial lavage fluid. The percentage of neutrophils correlated with IL-8 levels and exceeded 20% in 0 of 10 NS, 1 of 9 MS, 2 of 9 TS, and 5 of 10 MTS. We conclude that regular smoking of marijuana by young adults is associated with significant airway inflammation that is similar in frequency, type, and magnitude to that observed in the lungs of tobacco smokers.

Marijuana and cocaine impair alveolar macrophage function and cytokine production

Use of marijuana and cocaine is on the rise in the United States. Although pulmonary toxicity from these drugs has occasionally been reported, little is known about their effects on the lung microenvironment. We evaluated the function of alveolar macrophages (AMs) recovered from the lungs of nonsmokers and habitual smokers of either tobacco, marijuana, or crack cocaine. AMs recovered from marijuana smokers were deficient in their ability to phagocytose Staphylococcus aureus (p < 0.01). AMs from marijuana smokers and from cocaine users were also severely limited in their ability to kill both bacteria and tumor cells (p < 0.01). Studies using NG-monomethyl-L-arginine monoacetate, an inhibitor of nitric oxide synthase, suggest that AMs from nonsmokers and tobacco smokers were able to use nitric oxide as an antibacterial effector molecule, while AMs from smokers of marijuana and cocaine were not. Finally, AMs from marijuana smokers, but not from smokers of tobacco or cocaine, produced less than normal amounts of tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, and interleukin-6 when stimulated in culture with lipopolysaccharide. In contrast, the production of transforming growth factor-beta, an immunosuppressive cytokine, was similar in all groups. These findings indicate that habitual exposure of the lung to either marijuana or cocaine impairs the function and/or cytokine production of AMs. The ultimate outcome of these effects may be an enhanced susceptibility to infectious disease, cancer, and AIDS.

Tracheobronchial histopathology in habitual smokers of cocaine, marijuana, and/or tobacco

BACKGROUND

Marijuana and alkaloidal cocaine ("crack") are the two most commonly smoked substances in the United States after tobacco. While regular tobacco smoking has been found to be associated with extensive microscopic alterations in bronchial mucosa, little information is available concerning the effect of crack cocaine and marijuana on tracheobronchial histopathology.

STUDY OBJECTIVE

To determine the relative impact of smoked substances (cocaine, marijuana, and tobacco) alone and in combination on the histopathology of the tracheobronchial mucosa and to assess whether the effects of habitual smoking of two or more substances (cocaine, marijuana, and/or tobacco) are additive.

DESIGN

Observational cohort study.

SUBJECTS

Fifty-three nonsmoking control subjects (NS), 14 current, habitual smokers of crack cocaine only (CS), 40 current, regular smokers of marijuana only (MS), 31 regular smokers of tobacco only (TS), 16 current smokers of both cocaine and marijuana (CMS), 12 current smokers of both cocaine and tobacco (CTS), 44 current smokers of both marijuana and tobacco (MTS), and 31 current smokers of cocaine, marijuana, and tobacco (CMTS).

METHODS

After preliminary screening evaluation, including a detailed respiratory and general health questionnaire and routine pulmonary function studies, subjects underwent fiberoptic bronchoscopy with endobronchial biopsies of the mucosa of the primary carina and randomly selected secondary or tertiary carinae. Biopsy specimens were processed for light microscopy, stained with hematoxylin-eosin or periodic acid-Schiff, and examined to assess epithelial, basement membrane, and submucosal alterations by one or two pathologists who were masked to the smoking status of the subject.

RESULTS

Smokers of cocaine, marijuana, or tobacco alone all exhibited more frequent abnormalities than NS in 10 (CS) or all 11 (MS and TS) of the histopathologic features assessed. For most features, MS and TS showed significantly more frequent alterations than NS (p < or = 0.02), while CS showed significantly more frequent abnormalities than NS in only three features (p<0.05) and nearly significant differences from NS in two additional features (p < or = 0.09). Alterations were noted most frequently in CTS (six features) and MTS (three features), while abnormalities were relatively infrequent in CMS. For 10 features, MTS had more frequent alterations than MS and TS. With a single exception, CMTS did not show more frequent alterations than CTS or MTS.

CONCLUSION

Marijuana and tobacco smoking each produces significant bronchial mucosal histopathology and the effects of marijuana and tobacco appear additive. Cocaine appears to lead to fewer significant bronchial mucosal alterations than marijuana or tobacco when smoked alone and does not add to the changes associated with marijuana. When smoked together with tobacco, however, cocaine appears to augment the bronchial injury caused by tobacco smoking.

Acute activation of circulating polymorphonuclear neutrophils following in vivo administration of cocaine. A potential etiology for pulmonary injury

Crack cocaine has become a major drug of abuse in the United States and its use is associated with a broad spectrum of pulmonary complications. The present study was conducted to determine whether controlled in vivo administration of cocaine (inhaled or IV) alters the function of circulating inflammatory cells in a manner capable of contributing to acute lung injury. Subjects who regularly smoked crack cocaine were asked to abstain from illicit drug use for at least 8 h, and were then administered one of the following treatments on each of 4 study days: inhaled cocaine base (45 mg), inhaled placebo (4.5 mg cocaine base, a subphysiologic dose), IV cocaine HCl (0.35 to 0.50 mg/kg), or IV placebo (saline solution). Samples of blood were obtained from a peripheral venous catheter and blood cells were isolated before and 10 to 45 min after treatment. The administration of either cocaine base or cocaine HCl, but not their corresponding placebos, resulted in the activation of circulating polymorphonuclear neutrophils (PMNs). Exposure to cocaine in vivo enhanced the antibacterial activity of PMNs, as measured by their ability to kill Staphylococcus aureus. Antitumor activity, as measured in an antibody-dependent cell-mediated cytotoxicity assay, also increased following short-term administration of cocaine. Finally, short-term exposure to cocaine enhanced production of interleukin 8, a potent PMN chemoattractant and neutrophil-activating factor associated with both acute and chronic lung injury. These studies demonstrate that short-term in vivo exposure to cocaine activates the effector function and cytokine production of circulating PMNs. Therefore, it is possible that bursts of acute inflammatory activity resulting from crack use could contribute to lung injury.

A comparison of gene transfer methods in human dendritic cells

Dendritic cells (DCs) are the most potent antigen-presenting cells (APCs) for the initiation of antigen-specific T-cell activation. DCs may be highly enriched from peripheral blood-adherent leukocytes by short-term (7-day) culture in the presence of interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor. Various methods of gene transfer were studied, including DNA/liposome complexes, electroporation, CaPO4 precipitation, and recombinant adenovirus (AdV) vectors. Low levels of expression were obtained with the physical methods tested. In contrast, AdV vectors expressing luciferase, beta-galactosidase, IL-2, and IL-7 all readily transduced human DCs. Increasing levels of gene expression were observed over a range of multiplicity of infection (MOI) of 10:1 to 10,000:1, with transduction efficiencies exceeding 95% at higher MOI. Although levels of maximal gene expression in DCs were significantly lower than those obtained using human tumor cell lines, IL-2 and IL-7 production of up to 5 x 10(2) ng/10(6) DC were achieved. These results suggest that AdV vectors are a promising vehicle for genetically engineering human DCs.

Interleukin-7 gene transfer in non-small-cell lung cancer decreases tumor proliferation, modifies cell surface molecule expression, and enhances antitumor reactivity

Cytokine gene transfer to tumor cells can augment host antitumor responses and modify tumor phenotype. To evaluate the immunoregulatory and antitumor capacities of lung tumor-derived interleukin-7 (IL-7), we transduced non-small-cell lung cancer (NSCLC) cell lines with the IL-7/HyTK internal ribosomal entry site (IRES) retroviral vector and evaluated modifications in tumor phenotype and cocultured effector activities. In vitro proliferation of IL-7-transduced tumor cells was significantly less than control vector-transduced and parental tumor cells. The decreased proliferation rates of IL-7-transduced cells could be reproduced by adding high concentrations of recombinant IL-7 to the parental cells. Anti-IL-7 monoclonal antibody significantly increased the proliferation of the IL-7-transduced cells (P < .05). Parental NSCLC cells were found to express the IL-7 receptor, and IL-7 gene transduction did not alter expression of the IL-7 receptor. IL-7 transduction significantly altered tumor cell expression of intracellular adhesion molecule 1, major histocompatibility complex 1, lymphocyte function-related antigen 3, very late activation antigen beta 1, and p185neu. Peripheral blood lymphocytes cocultured with either IL-7-transduced tumor cells or tumor supernatants had enhanced cytolytic and proliferative capacities compared with coculture with control vector-transduced or parental cells. Our findings indicate that IL-7 gene transfer in NSCLC significantly augments cocultured effector activities in vitro, inhibits tumor cell proliferation, and modifies tumor cell surface phenotype. These findings suggest that IL-7 gene therapy may be effective in modifying host antitumor responses in NSCLC.

Human CD14+ leukocytes acquire the phenotype and function of antigen-presenting dendritic cells when cultured in GM-CSF and IL-4

The combination of granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-4 (IL-4) induces the growth of antigen-presenting cells (APC) from adherent peripheral blood leukocytes. These cells have been characterized as dendritic cells (DC), yet many questions exist regarding their relationship to other DC populations and the nature of their progenitors. To address these issues, we utilized a combination of immunomagnetic depletion, cell sorting, and cell culture to isolate four distinct APC populations; macrophages expressing high levels of CD14 (CD14bright macrophages), DC produced by culturing adherent cells in GM-CSF and IL-4 (cultured DC), and two different subsets of fresh DC that express low levels of CD14 (CD14dim DC). Each population exhibited a unique morphology and a unique profile of cell surface markers. In contrast to macrophages,all three DC populations expressed the DC marker CD83, as well as highlevels of MHC molecules and the costimulatory molecules B7-1 (CD80) and B7-2 (CD86). In addition. all three DC populations presented soluble tetanus toxin antigen and stimulated T cell proliferation to levels far superior to that of macrophages. Blocking studies demonstrated a costimulatory role for B7-1, B7-2, and CD40 in antigen presentation, although B7-2 expression was the single most important factor. To identify the progenitors of cultured DC, we sorted the adherent fraction of PBMC into discrete subpopulations prior to exposure to GM-CSF and IL-4. DC activity derived entirely from CD14+ precursors and was equally demonstrable using either the CD14dim or CD14bright subsets. Although these DC precursors lost expression of CD14 in culture, they maintained most of their other myeloid features. We conclude that human CD14+ leukocytes acquire the phenotype and function of DC when cultured in GM-CSF and IL-4.

Effects of smoking marijuana, tobacco or cocaine alone or in combination on DNA damage in human alveolar macrophages

This study examined the role of marijuana smoking in the pathogenesis of human lung cancer by measuring DNA damage in alveolar macrophages (AM). The alkaline unwinding method was used to determine DNA single-strand breaks in AM lavaged from non-smokers [NS] and smokers of marijuana [MS], tobacco [TS] or cocaine [CS], either alone or in combination. DNA damage was related to superoxide anion (O2-) production by AM stimulated with phorbol myristate acetate (PMA) and to nitric oxide content of smoke using cellular nitrite (NO2-) concentrations. The percentage of double-stranded DNA present after alkaline unwinding was higher in AM of NS (41 +/- 5% [11]) and CS (41 +/- 4% [9]) versus that of MS (31 +/- 4% [8]), TS (35 +/- 3% [11]), MTS (26 +/- 4% [3]), and CTS (27 +/- 5%* [10]), mean +/- SEM [n], * = p < 0.1 vs. NS). PMA stimulated O2- production by AM from NS and CS was lower than that of other smokers, but the differences were not significant. O2- release, however, had an inverse correlation with DNA single-strand breaks (r = -0.38, p = 0.009). Nitrite content of AM from NS and CS was less than that of other smokers' cells (p < 0.1 for TS & CTS vs. NS), but DNA damage had no relationship to NO2- concentration. We conclude that AM recovered from MS, either alone or in combination with tobacco smoking, show a trend towards DNA damage. Studies utilizing a larger population should verify our findings and further define its relationship to enhanced oxidant production by macrophages.

Interleukin 2 induces the expression of CD45RO and the memory phenotype by CD45RA+ peripheral blood lymphocytes

The CD45RA and CD45RO isoforms of the leukocyte common antigen identify functionally distinct "naive" and "memory" T cell subsets. While antigenic and mitogenic stimuli are known to initiate transition from the naive to memory state, little is known about the role of cytokines in this process. This report demonstrates that in vitro exposure of purified CD45RA+/CD45RO- peripheral blood lymphocytes (PBL) to interleukin 2 (IL-2) promotes their conversion to the CD45RA-/CD45RO+ phenotype. Conversion to CD45RO occurs for both the CD3+ and CD3-/CD56+ lymphocyte subsets, but occurs more rapidly, and at lower IL-2 concentrations, in the CD3-/CD56+ population. Expression of CD45RO was observed only in response to IL-2 and was not observed during long-term culture in IL-4, IL-6, or IL-7. We also examined the effect of IL-2 on the expression of adhesion molecules by T cells. The expression of CD2, CD11a, and CDw29 increased, and expression of Leu-8 (LAM-1) decreased, on cultured CD45RA+/CD45RO- cells after they converted to expression of CD45RO. In contrast, lymphocytes that remained CD45RA+/CD45RO- after 10 d in culture exhibited no change from their baseline adhesion molecule profile. Finally, to test the role of endogenous IL-2 during T cell activation we stimulated CD45RA+/CD45RO- PBL with immobilized anti-CD3 in the presence of neutralizing anti-IL-2 antibody and/or cyclosporin A. Both agents significantly reduced the expression of CD45RO and the effect of cyclosporin A was reversed by exogenous IL-2. We conclude that IL-2 promotes CD45RA+ cells to express the memory phenotype and is a mediator of CD45RO expression after stimulation of the T cell receptor/CD3 complex.

Inhibition of natural killer cell activity by therapeutic levels of theophylline

Theophylline, as used for the treatment of asthma and chronic obstructive pulmonary disease, may have several effects, including direct bronchodilation, improvement in diaphragmatic and ciliary function, and possibly immune modulation. In this study, we quantified the capacity for theophylline to inhibit natural killer (NK) cells and investigated the mechanism(s) that mediate this inhibition. Theophylline at 10 micrograms/ml and 20 micrograms/ml inhibited the tumoricidal activity of isolated peripheral blood lymphocytes (PBL) by 19 +/- 5% and 36 +/- 6%, respectively (n = 6). Using fluorescence-activated cell sorting, we purified NK cells from PBL and tested theophylline's effects on the kinetics of tumor lysis (Vmax) and on tumor binding. Theophylline at 20 micrograms/ml reduced Vmax by 40 +/- 9% but had no effect on tumor binding. We compared the effects of theophylline, which is both a phosphodiesterase (PDE) inhibitor and an adenosine receptor (AdR) antagonist, with agents that range from relatively pure AdR antagonists to pure PDE inhibitors. Inhibition of NK activity occurred only with PDE inhibitors. We also extracted lymphocyte PDE and observed a direct correlation (r2 = 0.99) between theophylline's activity as a PDE inhibitor and its capacity to inhibit NK activity. These results suggest that theophylline inhibits NK cytotoxicity through its activity as a PDE inhibitor. The clinical relevance of these findings awaits further study.

Pulmonary surfactant inhibits interleukin-2-induced proliferation and the generation of lymphokine-activated killer cells

The generation of lymphokine-activated killer (LAK) cell activity and the proliferative response to human recombinant interleukin-2 (IL-2) were significantly reduced when either human peripheral blood lymphocytes (PBL) or purified CD56+/CD3- lymphocytes were cultured in the presence of pulmonary surfactant. Surfactant concentrations ranging between 30 and 500 micrograms/ml produced increasing levels of inhibition ranging from 20 to 95%. For any given concentration of surfactant, increasing the IL-2 concentration produced increasing levels of LAK activity but never overcame the suppressive effects of the surfactant. Time course studies demonstrated that surfactant is inhibitory only if added to PBL during the first 2 days of IL-2 culture, suggesting a preferential action during the induction phase of LAK activity. Pretreatment of PBL with surfactant for as little as 2 to 4 h inhibited their subsequent response to IL-2 culture, suggesting that inhibition is rapid, persistent, and directly due to alterations in PBL responsiveness. To determine if surfactant alters cell membrane function, we measured the effects of surfactant exposure on LAK:tumor binding. Binding of LAK cells to both K562 and M14 tumor targets was inhibited in a concentration-dependent manner. Concurrently, we observed a reduced expression of IL-2 alpha-chain receptors on surfactant-treated CD56+/CD3- cells and a dramatic reduction in the expression of adhesion molecules including CD2, LFA-1, LFA-3, and ICAM-1. We conclude that pulmonary surfactant has the potential to suppress cytotoxic and proliferative responses to IL-2, alters cell-to-cell interactions, and reduces the expression of activation and adhesion molecules on LAK cells.

Regulation of natural killer function by nonlymphoid cells

Natural killer (NK) cells and interleukin-2 activated NK cells, termed lymphokine-activated killer (LAK) cells, can lyse tumor cells without restriction by the MHC complex. The cytotoxic activity of these cells is subject to regulation by nonlymphoid cells in vitro. Interaction of NK cells with red blood cells (RBC) increases NK cytotoxicity. Interaction with polymorphonuclear neutrophils (PMN) suppresses LAK development and also inhibits NK- and LAK-mediated cytotoxicity at the effector cell phase. Exposure to tumor necrosis factor-alpha greatly enhances the inhibitory effect of PMN at the effector cell phase. Depending on their states of activation and differentiation, monocytes have the capacity to either enhance or suppress LAK induction. In contrast, macrophages derived from the lung are potent inhibitors of NK and LAK activity at both the induction and effector cell phases. Several cytokines are secreted by monocytes and macrophages and these include both suppressive and enhansive factors of cytotoxic function. Platelets are also capable of releasing suppressive factors. NK cells are believed to be involved in host surveillance of tumors, control of microbial infections and regulation of hematopoiesis. Regulation of NK cells by nonlymphoid cells and their products likely provides an in vivo mechanism for locally regulating NK function.

Pulmonary macrophages suppress the proliferation and cytotoxicity of tumor-infiltrating lymphocytes

Adoptive immunotherapy with interleukin-2 and tumor-infiltrating lymphocytes (TIL) is rarely effective in primary lung cancer. We hypothesize that pulmonary macrophages (PM), which are increased substantially in the lungs of smokers, might suppress TIL function. The addition of PM into the TIL cytotoxicity assay produced a concentration-dependent suppression of TIL cytotoxicity with up to 71% inhibition of autologous tumor killing at the 1:1 PM:TIL ratio. Inhibition was not target-specific, as killing of NK-sensitive (K562), NK-resistant (M14), and autologous tumor targets were equally suppressed. Nor was inhibition specific for lung TIL, as similar inhibition was observed with melanoma and renal TIL. Using a model system, we demonstrated that both CD3+ antigen-specific and CD56+ nonspecific lymphocytes are susceptible to the suppressive effects of the PM. Direct co-incubation of PM and TIL for 4 to 44 h resulted in progressive suppression of TIL proliferation and cytotoxicity. TIL cytotoxicity remained suppressed even if PM were removed from the co-culture after 24 h, but was restored if the separated TIL were re-incubated in interleukin-2. These results suggest that PM may locally regulate the proliferative and cytotoxic function of adoptively transferred TIL.

Human pulmonary macrophages utilize prostaglandins and transforming growth factor beta 1 to suppress lymphocyte activation

The ability to activate peripheral blood lymphocytes (PBLs) in vitro with interleukin-2 (IL-2) is suppressed by the presence of autologous human pulmonary alveolar macrophages (AMs). AMs suppress both IL-2-induced proliferation and the induction of lymphokine-activated killer cell (LAK) activity in a dose-dependent manner (79 +/- 6% suppression of LAK activity at a 0.25:1 AM/PBL ratio). Increasing the IL-2 concentration increased baseline LAK activity but did not prevent AM-mediated suppression. At least two different mechanisms of suppression were observed, one diffusible in nature and the other contact dependent. Indomethacin prevented the component of inhibition that diffused across porous polycarbonate membranes, indicating prostaglandins as the diffusible inhibitor. In contrast, indomethacin had no effect when added alone into conventional AM-PBL cocultures, but a combination of indomethacin and anti-transforming growth factor beta 1 (TGF-beta 1) antibody did prevent inhibition. This result suggests that TGF-beta 1 acts as an additional contact-dependent inhibitor. PBLs that were rendered unresponsive to IL-2 completely recovered their responsiveness within 4 days after removing AMs from the coculture. These features suggest that pulmonary macrophages have multiple mechanisms for locally suppressing IL-2 responses and lymphocyte activation.

Expression of CD45 isoforms in fresh and IL-2-cultured tumor-infiltrating lymphocytes from basal cell carcinoma

Immunohistochemistry and flow cytometry analyses were performed to characterize the specific T cell subpopulations infiltrating basal cell carcinomas (BCC) and to determine their phenotypic response to in vitro expansion with IL-2. Tumor-infiltrating lymphocytes (TIL) within BCC predominantly expressed the CD45RO (activated or "memory") phenotype (65 +/- 3%) and the percentage of TIL expressing CD45RO consistently increased when cultured in vitro with IL-2 (85 +/- 5%). In comparison, fresh normal peripheral blood lymphocytes predominantly expressed the CD45RA (naive) phenotype (79 +/- 4%), but shifted to the expression of CD45RO following in vitro expansion in IL-2 (86 +/- 6%). To determine whether IL-2 alone, in the absence of antigen or mitogen, can promote naive lymphocytes to convert from the expression of the CD45RA isoform to the CD45RO isoform, we cultured purified CD45RA+ lymphocytes in IL-2. After three weeks in culture, 90% of the lymphocytes expressed exclusively CD45RO. We conclude that tumor-infiltrating lymphocytes from BCC predominantly express CD45RO and that this expression may represent specific antigen stimulation and/or in situ activation by cytokines.

Antimicrobial and respiratory burst characteristics of pulmonary alveolar macrophages recovered from smokers of marijuana alone, smokers of tobacco alone, smokers of marijuana and tobacco, and nonsmokers

Rodent studies indicate that marijuana smoke can adversely affect the antimicrobial function of pulmonary alveolar macrophages (PAM). To evaluate whether marijuana smoke similarly affects human PAM, we compared phagocytosis, fungistatic/fungicidal activity, and superoxide anion (O2-) production of PAM recovered from marijuana smokers (MS), tobacco smokers (TS), marijuana and tobacco smokers (MTS), and nonsmokers (NS). Although PAM from the four groups were equally capable of ingesting Candida albicans, the macrophages from smokers differed from normal PAM in their ability to restrict intracellular yeast germination (ungerminated candida in smokers' PAM = 68 +/- 3% [46] versus NS = 54 +/- 6% [17], mean +/- SEM [n], p = 0.022). Despite heightened fungistatic activity, PAM from MS and TS destroyed significantly fewer intracellular yeast (28 +/- 2 and 29 +/- 2%, respectively) after 4 h than did macrophages recovered from NS (40 +/- 4%, p less than 0.05). Both basal and stimulated (dihydrocytochalasin B + opsonized zymosan or phorbol myristate acetate) O2- production were similar in PAM from MS and NS, but significantly increased in PAM from TS (p less than 0.05). Our findings indicate that marijuana smoking does not alter the phagocytic behavior or the respiratory burst of human PAM, but marijuana smoking does decrease the ability of human PAM to destroy ingested Candida albicans. These findings contrast with the effects of tobacco smoking, which not only decreases the fungicidal activity of human PAM but also increases their respiratory burst.

Marijuana smoking, pulmonary function, and lung macrophage oxidant release

Pulmonary alveolar macrophages lavaged from tobacco smokers release increased levels of oxidants and have been implicated in the pathophysiology of emphysema. It is unknown whether lung macrophages recovered from marijuana smokers also liberate excessive levels of oxidants. To evaluate this possibility, pulmonary alveolar macrophages were obtained by bronchoalveolar lavage from nonsmokers, smokers of marijuana only, smokers of tobacco only, and smokers of tobacco plus marijuana. Spontaneous and stimulated superoxide anion release was measured by the superoxide dismutase-inhibitable reduction of ferricytochrome c. These findings were correlated with recent lung function tests. Superoxide anion production by macrophages, studies of small airway integrity (closing volume, closing capacity, and the slope of Phase III of the single-breath nitrogen washout curve), and evaluation of alveolar gas exchange (diffusing capacity of carbon monoxide) were similar in both nonsmokers and marijuana smokers. However, tobacco smoking was associated with both significantly higher levels of superoxide anion release by pulmonary alveolar macrophages and significant abnormalities of small airway function and alveolar diffusing capacity. Based on the results of this study, pulmonary alveolar macrophages of marijuana-only smokers do not produce increased amounts of oxidants when compared to macrophages of non-smoking subjects. This observation may account for the absence of abnormalities in small airway function and alveolar diffusing capacity in marijuana-only smokers, in contrast to the presence of such findings in smokers of tobacco, regardless of marijuana use.

Inhibition of lymphokine-activated killer cell function by human alveolar macrophages

Tissue- and organ-specific factors may be important in the regulation of cytotoxic lymphocytes. We therefore examined the ability of human alveolar macrophages (AMs) to alter the tumoricidal function of lymphokine-activated killer cells (LAK cells). AMs, obtained by bronchoalveolar lavage from healthy volunteers, or peripheral blood monocytes were added to a standard 4-h chromium release LAK assay at varying concentrations. AMs severely inhibited the killing of both NK-sensitive (K562) and NK-resistant (M14) tumor cells [42 +/- 2.6% (SEM) inhibition of M14 killing at the 0.125:1 AM:LAK ratio and 83 +/- 2.3% inhibition at the 1:1 ratio, n = 9]. Peripheral blood monocytes, in contrast, were only one-eighth as inhibitory as AMs. A positive smoking history was associated with a 3- to 7-fold increase in the number of AMs recovered by bronchoalveolar lavage but had no effect on the inhibition produced per AM cell. The mechanism of inhibition was investigated. Formalin fixation produced an 8-fold reduction in the inhibitory capacity of AMs, suggesting the need for active metabolism or an intact cell membrane. No soluble mediator could be detected with a two-chamber Transwell system, in 24-h AM culture supernatants, or following blocking experiments with indomethacin, catalase, or superoxide dismutase. Binding studies demonstrated selective binding between LAK cells and AMs, yet AMs were not susceptible to LAK-mediated lysis under the usual assay conditions. In summary, AMs are potent inhibitors of in vitro LAK function. Inhibition requires direct cell contact and is independent of soluble reactive oxygen species, prostaglandins, or activation by tobacco smoking. Inhibition is not due to lysis of the AM as a competitive cold target. These results suggest that AMs may actively limit antitumor cytotoxic responses in the lung.

Maxillary dental arch dimensions following pharyngeal-flap surgery

Pharyngeal-flap surgery (PFS) is a surgical procedure utilized in the treatment of hypernasal speech. The purpose of this study was to evaluate the effect of PFS on the maxillary dental arch. Sixteen patients who had undergone PFS between the ages of 5 and 7 years were selected from the longitudinal growth study of the Lancaster Cleft Palate Clinic. Eight points were marked on the occlusal surfaces of serial maxillary dental models to determine arch width and length. These data were compared to a matched sample of patients from the same growth study who did not undergo PFS. The flap group demonstrated significant reduction in both arch width (at cuspids and molars) and arch length development compared to the control sample, following PFS. These results are not inconsistent with an hypothesis of dental-arch form changes related to possible airway obstruction following PFS, although data on the latter were not available on this sample.

Gas flow through a bronchopleural fistula. Measuring the effects of high-frequency jet ventilation and chest-tube suction

High-frequency jet ventilation (HFJV) is FDA-approved for ventilating patients with bronchopleural fistulae (BPF), yet little is known about its effect on the fistula airleak. We quantitated a patient's BPF airleak during both conventional volume-cycled ventilation and HFJV. The effect of chest-tube suction (CTS) on BPF flow was also studied. Despite a significant reduction in peak airway pressure, the HFJV resulted in a 50-70 percent increase in BPF flow. CTS also significantly increased the airleak. HFJV may not always be the preferential method for ventilating patients with BPF and we recommend measuring the fistula airleak when attempting to optimize a patient's ventilatory parameters.

Dilemma of Tarasoff: must physicians protect the public or their patients?

Physicians nationwide, already worried by an increasing number of professional liability lawsuits and an expanding scope of liability, now face a new and potentially more troublesome development that had its genesis in what many thought was an extraordinary court decision. In Tarasoff v. Regents of the University of California, a psychiatrist was held, in a suit brought by the victim's parents, to be liable for negligence in the death of a woman who was murdered by a patient of that physician. The court held that even though the physician had complied with the traditional duty of protecting the patient's confidentiality, he nonetheless had a duty to warn the victim of the potential threat against her life. Tarasoff was eventually followed by a number of decisions that imposed liability on physicians under similar circumstances.

This article reviews and analyzes the original Tarasoff decision and subsequent judicial rulings on this subject. In addition, the authors briefly explore the historical backdrop of this decision and suggest practical steps that physicians can take to deal with the conflicting duties of protecting confidentiality and protecting potential victims from the danger posed by patients.

Medical, legal and ethical issues in critical care

This report is intended to familiarize the reader with the current legislation concerning state definitions of death, the pertinent judicial decisions concerning termination of life support and the current status of medical/ethical committees. However, it is of paramount importance to all health care personnel to become involved in the resolution of these problems. Current information regarding legal clarity to these issues leaves much to be desired. Unless we wish major decisions that will affect us all to be decided by others, it is strongly suggested that we become directly involved in this process and accept the challenge and the opportunity to influence major legal, ethical, and medical decisions.

Cell-mediated immunity in chronically diabetic mice

A radioisotopic ear assay for delayed hypersensitivity (DH) to 2,4-dinitrofluorobenzene (DNFB) was used to investigate cellular immune function in chronic alloxan- diabetic C57BI/6 mice. The specific migration of 5-(125I)Iodo-2'-deoxyuridine-labeled monocytes to the site of antigenic challenge was employed to quantitatively measure the OH response. Although both normal and diabetic sensitized mice had a significantly greater DH response than nonsensitized controls, the response of diabetic mice was severely attenuated (23% of normal)

The effect of the delayed hypersensitivity response on spleen size was also investigated. In the nonsensitized state the spleens of diabetic mice were approximately 30% smaller than the spleens of normal mice. After sensitization with DNFB, and up to the time of antigenic challenge, the spleens from both diabetic and normal mice increased 2.1-fold in weight. After challenge, however, the diabetic spleen maintained its prechallenged size while the normal spleen increased an additional 30% in weight.

When either sensitized normal or diabetic spleen cells were passively transferred to nonsensitized normal recipient mice, a significant DH response was evoked after challenge with DNFB. This response was of equal magnitude after transfer of either the sensitized diabetic or normal spleen cells. The DH response after the passive transfer of spleencells from either normal or diabetic sensitized donors to diabetic recipients was very markedly attenuated and in fact questionably significant when compared with the nonspecific inflammatory response to DNFB.

These results indicate that an intact population of DNFB-sensitized cells exists in the diabetic, but that an inhibition of T-lymphocyte or monocyte activity is occurring during the secondary challenge. The chronic hypoinsulinemia, hyperglycemia, and catabolic metabolism of the alloxan-diabetic mouse does not qualitatively alter the immune cellular processes associated with primary sensitization but significantly attenuates the secondary response.

Induction of hyperglycemia with insulin antibodies to B-chain determinants

Insulin antibodies measured by a radioimmune method (ABR) are significantly better inducers of hyperglycemia than are insulin antibodies measured by an immune hemolysis method (ABH) when injected intraperitoneally into mice. The ability to induce hyperglycemia by an insulin antiserum can be predicted by the titer of ABR measured. ABR interact in vitro with determinants severely perturbed on nickel-insulin, partially perturbed on proinsulin and desasparagine-desalanine insulin, and unaffected on zinc-insulin or zinc-free monocomponent insulin. ABH, on the other hand, interact in vitro with determinants severely perturbed on proinsulin and desasparagine-desalanine insulin but stabilized on nickel-insulin and zinc-insulin. Since the connecting peptide of proinsulin is probably in apposition to the A-chain residues on the solvent surface, the more effective reaction of proinsulin with ABR than with ABH is submitted as evidence that ABR are directed toward residues on the B-chain surface of insulin. Because ABR are more effective inducers of hyperglycemia than are ABH, it is proposed that the degree of hyperglycemia induced by antibodies in vivo is a result of interactions with determinants on the B-chain surface of insulin. These results support the possibility that insulin in vivo is more accessible for interaction with antibodies directed to the B-chain of insulin. It is also possible that ABR, which are directed to B-chain determinants, are of higher affinity than is the affinity between insulin and receptors or that the active site of insulin for maintaining euglycemia includes the B-chain surface residues.