Elevated IP-10 and IL-6 from bronchoalveolar lavage cells are biomarkers of non-cavitary tuberculosis.

BACKGROUND: Active TB disease can destroy lung parenchyma leading to cavities. Immune responses that predispose or protect individuals from lung damage during TB are poorly defined. OBJECTIVE: To sample lung immune cells and assay bronchoalveolar lavage (BAL) cell cytokine production. DESIGN: Enrolled subjects (n = 73) had bilateral infiltrates and underwent BAL. RESULTS: All had sputum culture demonstrating Mycobacterium tuberculosis and 22/73 (30%) had cavities on their chest radiograph. Those with cavities at presentation had a higher percentage of polymorphonuclear neutrophils (PMN) in BAL as well as lower inducible protein (IP) 10 (P < 0.01) and interleukin (IL) 6 (P = 0.013) in BAL cell supernatants compared to those without cavities. There was no correlation between cavities and other BAL or serum cytokines. IP-10 was negatively associated with BAL PMN. IP-10 and IL-6 expression above median reduces the odds of cavities by 79% and 78% in logistic regression models. IP-10 and IL-6 clustered with interferon-gamma and tumour necrosis factor-alpha in a principal component analysis, while IL-4 clustered with PMN. CONCLUSION: Increasing IP-10 and IL-6 production by BAL cells is associated with non-cavitary TB in patients who present with radiographically advanced TB. IP-10 and IL-6 may reflect an effective T-helper 1 immune control pathway for TB, attenuating tuberculous lung destruction.

Mycobacterium tuberculosis induces CCL18 expression in human macrophages.

The interaction of Mycobacterium tuberculosis (MTB) with the immune system is mediated by cytokine and chemokine responses of macrophages and/or dendritic cells. Chemokine (C-C motif) ligand 18 (CCL18) and interleukin (IL)-10 are major factors secreted by phagocytes, postulated to recruit naïve T lymphocytes and inhibit pro-inflammatory cells. Our study investigated the role of CCL18 and IL-10 in an in vitro model of infection by MTB in human macrophages. CD14(+) monocytes, obtained from the peripheral blood of eight healthy donors, differentiated in monocyte-derived macrophages (MDM) with monocyte-colony stimulating factor (100 ng/ml) for 6 days, were stimulated in vitro with lipopolysaccharide (LPS) (1 microg/ml) and with heat killed MTB Hv37Ra (multiplicity of infection 1:5) for 24 h. Alveolar macrophages from five healthy donors were infected with MTB Hv37RA. CCL18 protein and mRNA were detected by enzyme-linked immunosorbent assay (ELISA) and real-time PCR, IL-10 levels by ELISA. Stimulation of MDM with LPS or MTB led to a significant increase in CCL18 protein (control 2.67 +/- 0.46 ng/ml, LPS 4.05 +/- 0.56 ng/ml, with MTB 6.70 +/- 1.59 ng/ml, n = 5, P < 0.05) and specific mRNA levels (control 0.09 +/- 0.01, LPS 0.24 +/- 0.11, with MTB 0.34 +/- 0.08 CCL18/Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), n = 3, P < 0.05). A significant increase of the production of CCL18 was observed in infected alveolar macrophages. IL-10 levels increased from 38.52 +/- 26.38 pg/ml in control cells to 1129.32 +/- 235.00 and 974.25 +/- 164.46 pg/ml in LPS and MTB treated cells, respectively (P < 0.05). Up-regulation of CCL18 and IL-10 in macrophages by MTB may be involved in the recruitment of naïve T cells in association with local suppressive immunity against intracellular pathogens. This could represent a mechanism of tolerance during the early phases of infection.

Prevalence of workplace exacerbation of asthma symptoms in an urban working population of asthmatics.

OBJECTIVES: We used an interviewer-administered questionnaire to investigate workplace exacerbation of asthma symptoms (WEAS) among low-income, minority, working asthmatics admitted Bellevue Hospital Center in New York City from 2001 to 2002. We hypothesized that a high prevalence of WEAS would be found in this population among all jobs held and a subset of individual occupational classifications. MEASUREMENTS AND MAIN RESULTS: Of 301 subjects, 51% reported WEAS in their current or most recent job; 71% reported WEAS in any job. Prevalences (95% confidence intervals) of WEAS in common job classifications were 61% (49-73%) in janitorial jobs, 50% (33-67%) in garment and textile manufacturing jobs, and 38% (23-55%) in construction jobs. CONCLUSION: WEAS is prevalent in this urban minority population.

Modification of the p53 transgene of a replication-competent adenovirus prevents mdm2- and E1b-55kD-mediated degradation of p53.

Clinical efficacy of adenovirus-mediated cancer gene therapy has been limited thus far. To improve its oncolytic effect, a replication-competent adenoviral vector was previously constructed to express high levels of p53 at a late time point in the viral life cycle. p53 expression from this vector improved tumor cell killing and viral spread in vitro. However, p53 function is antagonized by cellular mdm2 and adenoviral E1b-55kD, both of which are known to bind to and inactivate p53. Therefore, a new vector (Adp53W23S) that expresses a modified p53 transgene, which does not bind to E1b-55kd and mdm2, was constructed. The modified p53 protein was demonstrated to have a substantially prolonged half-life, and its localization was predominantly nuclear. Viral replication was unaffected by expression of the modified p53 and cancer cell killing was improved in vitro. However, in a xenograft model, efficacy was not significantly different from control virus. In conclusion, expression of a degradation-resistant p53 transgene late in the life cycle of a replication-competent adenovirus improves p53 stability and cancer cell killing in vitro. However, other factors, such as the adenoviral E1b-19kD and E1a proteins, which oppose p53 function, and limitations to viral spread need to be addressed to further improve in vivo efficacy.

Hypoxia reduces adenoviral replication in cancer cells by downregulation of viral protein expression.

Successful cancer therapy using replicating viral vectors relies on the spread of virus from infected to uninfected cells. To date, there has been limited clinical success in the use of replicating adenoviruses. In animal models, established xenograft tumors are rarely eliminated despite the persistence of high viral titers within the tumor. Hypoxia is a prevalent characteristic of solid tumors, whereas adenovirus naturally infects tissues exposed to ambient oxygen concentrations. Here, we report that hypoxia (1% oxygen) reduces adenoviral replication in H1299 and A549 lung cancer cells, BxPC-3 pancreatic cancer cells, LNCaP prostate cancer cells and HCT116 colon cancer cells. However, hypoxia does not reduce cell viability or restrict S-phase entry. Importantly, the production of E1a and fiber proteins under hypoxic conditions was substantially decreased at 24 and 48 h compared to room air controls. In contrast, Northern analysis showed similar levels of E1a mRNA in room air and hypoxic conditions. In conclusion, a level of hypoxia similar to that found within solid tumors reduces the replication of adenoviral vectors by reduction of viral protein expression without a reduction in mRNA levels. To further improve oncolytic therapy using a replicating adenovirus, it is important to understand the mechanism through which hypoxia and the virus interact to control expression of viral and cellular proteins, and consequently to develop means to overcome decreased viral production in hypoxic conditions.

Increased incidence of multidrug-resistant tuberculosis in diabetic patients on the Bellevue Chest Service, 1987 to 1997.

STUDY OBJECTIVES: To investigate the characteristics of tuberculosis infection in diabetic patients at Bellevue Hospital. DESIGN: We conducted a case-control study retrospectively reviewing the records of patients at Bellevue Hospital Center from 1987 to 1997 with a discharge diagnosis of tuberculosis and diabetes mellitus. SETTING: Bellevue Hospital Center is a 1,200-bed, inner-city municipal hospital located in the Lower East Side of New York City. PATIENTS: Fifty-three identified patients had verified tuberculosis infection and diabetes; of these, 50 charts were available for review. One hundred five control cases were selected from nondiabetic patients with a discharge diagnosis of tuberculosis during the same time period. MEASUREMENTS AND RESULTS: Thirty-six percent (18 cases) of the patients with diabetes and tuberculosis had multidrug-resistant tuberculosis (MDR-TB) compared to only 10% (10 cases) in the control group (p < 0.01) Controlling for homelessness, HIV status, and directly observed therapy, the relative risk of MDR-TB was calculated to be 8.6 (confidence interval, 3.1 to 23.6) in the diabetic group compared to the control group. CONCLUSIONS: There was a significant association between diabetes and MDR-TB. Diabetes continues to be a risk factor for tuberculosis and was associated with MDR-TB in our patients.

Medical aspects of global warming.

BACKGROUND: Global warming is caused by increased carbon dioxide (CO2)resulting in a greenhouse effect with enhanced warming of the earth. Measurements of CO2 show a steady increase over the past 30 years caused by the burning of fossil fuels and from the loss of natural CO2 sinks. A 100-year increase in global temperature by 0.3 to 0.6 degrees C is reflected in atmospheric warming, glacier shrinkage, and rising sea levels. OBJECTIVES: Planetary ecosystem dynamics are being altered, challenging public health. It is predicted that morbidity and mortality will increase as a result of heat stress, as seen in recent heat waves in the U.S. Weather disaster effects will increase in number and magnitude, and both noninfectious and infectious diseases may flourish. A significant challenge will be the changes in life cycles of microbial species due to the warmer environs. Specific increases in incidence have been noted for vector-borne diseases, in addition to pulmonary findings, cardiovascular morbidity, neurological diseases, and occupational diseases. CONCLUSIONS: Warming can be demonstrated by the observed changes that have already occurred in the environment, particularly the thinning of polar ice caps. The United States Global Research Program has been established to coordinate research activities, which responds to issues deemed important by the United Nations Framework Convention on Climate Change. Research issues pertain to the scientific uncertainties in the greenhouse effect, temperature measurements at various atmospheric levels and latitudes, and impact on biota redistribution. The Kyoto Protocol has mandated specific solutions, e.g., a 7% reduction in CO2 levels within 10 years. Future recommendations involve supporting new technologies that are available to decrease emissions as well as understanding the role that occupational and environmental specialists have in global warming recognition.

Malignant mesothelioma from neighborhood exposure to anthophyllite asbestos.

BACKGROUND: Anthophyllite asbestos has been reported to cause asbestosis, lung cancer, mesothelioma, and pleural plaques in occupationally exposed workers. Anthophyllite has also been associated with pleural plaques in Finland and Japan among those who live near mines and mills and have neighborhood or environmental exposure. METHODS: We evaluated a 38-year-old patient with pleural mesothelioma who lived, attended school, and delivered newspapers near a manufacturing facility that used exclusively anthophyllite asbestos fiber from ages 8-17 years. He had no work exposure to asbestos. RESULTS: The pleural mesothelioma was an epithelial type with tubulopapillary structures and was treated with an extrapleural pneumonectomy followed by radiation therapy. The malignant cells were positive by immunohistochemistry for cytokeratin but negative for carcinoembryonic antigen, S100, B72.3, and leu M1 antigen. Anthophyllite fibers were > 5 microm in length in lung tissue compared to 3 microm from a general population study. CONCLUSIONS: Anthophyllite asbestos has been associated with neighborhood environmental exposure and pleural plaques; we now report a neighborhood exposure and pleural mesothelioma.

In situ activation of helper T cells in the lung.

To better understand the lung and systemic responses of helper T cells mediating memory immunity to Mycobacterium tuberculosis, we used three- and four-color flow cytometry to study the surface phenotype of CD4(+) lymphocytes. Bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) samples were obtained from a total of 25 subjects, including 10 tuberculosis (TB)-infected subjects, 8 purified-protein-derivative-negative subjects, and 7 purified-protein-derivative-positive subjects. In marked contrast to CD4(+) lymphocytes from PB (9% +/- 5% expressing CD45RA and CD29), the majority (55% +/- 16%) of CD4(+) lymphocytes in BAL (ALs) simultaneously expressed CD45RA, a naïve T-cell marker, and CD29, members of the very late activation family. Further evaluation revealed that CD4(+) ALs expressed both CD45RA and CD45RO, a memory T-cell marker. In addition, the proportion of CD4(+) lymphocytes expressing CD69, an early activation marker, was drastically increased in BAL fluid (83% +/- 9%) compared to PB (1% +/- 1%), whereas no significant difference was seen in the expression of CD25, the low-affinity interleukin 2 receptor (34% +/- 15% versus 40% +/- 16%). More importantly, we identified a minor population of CD69(bright) CD25(bright) CD4(+) lymphocytes in BAL (10% +/- 6%) that were consistently absent from PB (1% +/- 1%). Thus, CD4(+) lymphocytes in the lung paradoxically coexpress surface molecules characteristic of naïve and memory helper T cells as well as surface molecules commonly associated with early and late stages of activation. No difference was observed for ALs obtained from TB-infected and uninfected lung segments in this regard. It remains to be determined if these surface molecules are induced by the alveolar environment or if CD4(+) lymphocytes coexpressing this unusual combination of surface molecules are selectively recruited from the circulation. Our data suggest that ex vivo experiments on helper T-cell subsets that display distinctive phenotypes may be pivotal to studies on the human immune response to potential TB vaccines.

Wild-type adenovirus decreases tumor xenograft growth, but despite viral persistence complete tumor responses are rarely achieved--deletion of the viral E1b-19-kD gene increases the viral oncolytic effect.

Strategies to target viral replication to tumor cells hold great promise for the treatment of cancer, but even with replicating adenoviruses complete tumor responses are rarely achieved. To evaluate replicating adenoviral vectors, we have used A549 human lung cancer nude mouse xenografts as a model system. Intratumoral injection of wild-type adenovirus (Ad309) significantly reduced tumor growth from day 14 (p = 0.04) onward; however, tumor volumes reached a plateau at day 50. At 100 days, high levels of titratable virus were present within persistent viable tumors. In contrast to viral injection into established tumors, when tumor cells were infected in vitro with wild-type virus and then mixed with uninfected tumor cells, 1% of infected cells was sufficient to prevent tumor establishment. An E1b-19kD-deleted viral mutant (Ad337) was more efficient than Ad309 in this cell-mixing model. Just 1 cell in 1000 infected with Ad337 prevented tumor growth. However, although better than wild-type virus, Ad337 was unable to eradicate established flank tumors. These data suggest that although replicating adenoviruses exhibit significant oncolytic activity, barriers within the established tumor, such as connective tissue and tumor matrix, may limit the spread of virus. Strategies to enhance viral spread through established tumors are therefore likely to greatly improve the therapeutic efficacy of replicating adenoviruses.

Inhibition of anchorage-independent growth and lung metastasis of A549 lung carcinoma cells by IkappaBbeta.

To evaluate the role of the NF-kappaB signaling pathway in oncogenic transformation, we expressed IkappaBbeta, a specific inhibitor of NF-kappaB, in two human lung adenocarcinoma cell lines, A549 and H441. Expression of IkappaBbeta significantly reduced NF-kappaB activation induced by cotransfection with p65/RelA or TNF-alpha and abrogated the basal NF-kappaB activity in A549 cells. Transfection of IkappaBbeta into A549, H441 and K-ras-transformed NIH3T3 cells suppressed anchorage-independent growth as measured by colony formation in soft agar. Anchorage-independent growth of vector-transfected A549 cells in reduced serum could be enhanced by both EGF and IGF-I. In contrast, only EGF but not IGF-I could induce anchorage-independent growth of IkappaBbeta-expressing A549 cells, suggesting that the IGF-I signaling pathway regulating growth and survival may be blocked by IkappaBbeta. Interestingly, expression of IkappaBbeta suppressed growth of A549 cells in low serum in vitro without affecting in vivo growth subcutaneously in nude mice. However, metastatic growth of IkappaBbeta-expressing A549 cells in the lungs of nude mice was significantly inhibited. These results provide evidence that NFkappaB plays an important role in anchorage-independent growth and metastatic growth of lung carcinoma cells.

Increasing incidence of Mycobacterium xenopi at Bellevue hospital: An emerging pathogen or a product of improved laboratory methods?

STUDY OBJECTIVES: To investigate the dramatic rise in number of Mycobacterium xenopi isolates identified in our mycobacteriology laboratory, and to determine if this increase was due to emerging clinical pathology or to changes in culture technique. DESIGN: Retrospective chart and laboratory review. SETTING: University-affiliated tertiary-care city hospital. PATIENTS: Eighty-one patients with a single culture positive for M xenopi from 1975 to 1994 (period 1), and 47 patients with two or more cultures positive from 1994 to 1998 (period 2). INTERVENTIONS: The Bellevue mycobacteriology laboratory changed the culture medium from solid Lowenstein-Jensen medium (used from 1975 to 1990) to the Septi-Check AFB System (Becton-Dickinson; Glencoe, MD; used from 1991 to 1994), to the Mycobacteria Growth Indication Tube (MGIT; Becton-Dickinson; used from 1995 to 1998). MEASUREMENTS AND RESULTS: We recovered 29 M xenopi isolates from 1975 to 1990, 12 isolates from 1991 to 1994, and 381 isolates from 1995 to 1998. We subsequently identified and reviewed the medical records of all 81 patients who were culture positive for M xenopi from 1975 to 1994 (period 1), and 46 patients who had two or more isolates culture positive for M xenopi from 1995 to 1998 (period 2). For period 1, 75% of the subjects were male, 80% were minority, and at least 43% were HIV positive. Only one patient had clinical M xenopi lung disease during this period. For period 2, 79% of the subjects were male, 83% were minority, and at least 58% were HIV positive; two additional patients were identified who had clinical M xenopi lung disease. CONCLUSIONS: The dramatic increase in M xenopi isolates noted in our hospital was due to a more sensitive laboratory isolation technique, rather than a true increase in clinical disease. Other hospitals utilizing MGIT systems for mycobacterial recovery should interpret positive M xenopi cultures with caution.

Correction of glycogen storage disease type II by enzyme replacement with a recombinant human acid maltase produced by over-expression in a CHO-DHFR(neg) cell line.

Inherited genetic deficiency of lysosomal acid alpha glucosidase or acid maltase (GAA) results in the autosomal recessive glycogen storage disease type II (GSD II). To investigate whether we could generate a functional recombinant human GAA (rhGAA) for enzyme replacement therapy, we subcloned the cDNAs for human GAA and mouse dihydrofolate reductase (DHFR) into DHFR(neg) Chinese hamster ovary cells and established a stable cotransformant that expressed rhGAA. We cultured the recombinant cells in media with progressively increasing concentrations of methotrexate and found that human GAA enzyme activity increased to over 2,000 IU per gram protein. Importantly, the human GAA enzyme activity correlated to equivalent amounts of human GAA protein by rocketimmunoelectrophoresis. We confirmed that the human GAA enzyme activity corresponded to an amplification in human GAA mRNA by Northern analysis and human GAA cDNA copy number by Southern analysis. Exposing the rhGAA to human GSDII fibroblast cells or patient's lymphocytes or monocytes resulted in uptake of the rhGAA and reversal of the enzymatic defect. Mannose-6-phosphate in the media blocked uptake. GAA -/- mice were treated with the rhGAA at 1 mg/kg, which resulted in heterozygous levels of GAA in tissues, most notably skeletal muscle, heart and diaphragm after two infusions. More importantly, after multiple infusions, hind, and fore-limb muscle weakness was reversed. This rhGAA would be ideal for enzyme replacement therapy in GSD II.

Hut lung. A domestically acquired particulate lung disease.

We report an illustrative case of advanced "hut lung," or domestically acquired particulate lung disease (DAPLD), in a recently emigrated nonsmoking Bangladeshi woman with a history of 171 hour-years of exposure to biomass smoke. She presented with symptoms of chronic cough, dyspnea, and early parenchymal lung disease. High-resolution computed tomography (CT) of the chest demonstrated numerous 2- to 3-mm nodules, sparing the pleural surface. To our knowledge, this is the first such report of CT findings in the literature. Bronchoscopy yielded typical anthracotic plaques and diffuse anthracosis with interstitial inflammation on histopathologic examination of biopsy specimens. DAPLD is potentially the largest environmentally attributable disorder in the world, with an estimated 3 billion people at risk. Caused by the inhalation of particles liberated from the combustion of biomass fuel, DAPLD results in significant morbidity from infancy to adulthood. Clinically, DAPLD manifests a broad range of disorders from chronic bronchitis and dyspnea to advanced interstitial lung disease and malignancy. While a detailed environmental history is essential for making the diagnosis in most individuals, for patients with advanced DAPLD, invasive modalities such as bronchoscopy with transbronchial biopsy and examination of bronchoalveolar lavage fluid help differentiate it from other diseases. Recognition of this syndrome and removal of the patient from the environment is the only treatment. The development of well-controlled interventional trials and the commitment of sufficient resources to educate local populaces and develop alternative fuel sources, stove designs, and ventilation are essential toward reducing the magnitude of DAPLD.

Differentiation of monocytes to macrophages switches the Mycobacterium tuberculosis effect on HIV-1 replication from stimulation to inhibition: modulation of interferon response and CCAAT/enhancer binding protein beta expression.

HIV-1 replication is inhibited in uninflamed lung macrophages and is stimulated during tuberculosis. Attempts to recapitulate activation of HIV-1 replication in primary monocytes and macrophages ex vivo and in the untreated and PMA-treated THP-1 cell line model in vitro have produced opposite results depending on the state of differentiation of the cells. After infection with Mycobacterium tuberculosis, monocytes enhanced HIV-1 replication and produced a stimulatory 37-kDa CCAAT/enhancer binding protein beta (C/EBPbeta) transcription factor, whereas macrophages suppressed HIV-1 replication and produced an inhibitory 16-kDa C/EBPbeta transcription factor. IFN-beta induced inhibitory 16-kDa C/EBPbeta in macrophages, but had no effect on C/EBPbeta expression in monocytes. Macrophages, but not monocytes, were able to activate IFN-stimulated gene factor-3 (ISGF-3), a transcription factor composed of STAT-1, STAT-2, and IFN regulatory factor (IRF)-9, after infection with M. tuberculosis or stimulation with type I IFN. Macrophages expressed IRF-9 DNA-binding activity, but monocytes did not, and addition of the IRF-9 component reconstituted ISGF-3 in extracts of IFN-treated monocytes. Modulation of IFN responsiveness upon differentiation occurred at least in part through a post-transcriptionally regulated increase in IRF-9 expression. Both monocytes and macrophages maintained IFN responsiveness, activating STAT-1 homodimer formation and transcription of the STAT-1 gene after IFN stimulation. In addition, both monocytes and macrophages were able to activate NF-kappaB upon infection with M. tuberculosis. These results show that induction of ISGF-3, expression of the inhibitory 16-kDa C/EBPbeta, and suppression of HIV-1 replication via a transcriptional mechanism are macrophage-specific responses to infection with M. tuberculosis.

Specific cell targeting for delivery of toxins into small-cell lung cancer using a streptavidin fusion protein complex.

New modalities of treatment for small-cell lung cancer (SCLC) are needed, because the majority of patients continue to die of disseminated disease despite an initial response to conventional chemotherapy. Abnormal surface expression of the neural-cell adhesion molecule (NCAM) has been noted to be highly associated with SCLC. We examined the ability and efficiency of a streptavidin-Protein A (ST-PA) fusion protein complexed with an anti-NCAM monoclonal antibody (Mab) to transfer biotinylated beta-galactosidase into human SCLC cell lines NCI-H69, NCI-H526, and NCI-H446. When the surface molecule NCAM was targeted with this system, more than 99% of the targeted cells internalized and exhibited beta-galactosidase activity. In addition, we evaluated cytotoxic activity against SCLC lines NCI-H69 and NCI-H526 by efficient delivery of biotinylated glucose oxidase using the same ST-PA/anti-NCAM Mab complex. Cytotoxicity of the transduced cells (SCLC) was 10-fold and 100-fold greater, respectively, than the glucose oxidase control. This system could be widely applied for specific therapy of cancer cells by targeting unique surface molecules (antigens) using the corresponding Mab/ST-PA complex to transfer a variety of effector molecules; e.g., immunotoxic compounds, into target cells with a high degree of efficiency and specificity.

Deletion of the adenoviral E1b-19kD gene enhances tumor cell killing of a replicating adenoviral vector.

Replicating adenoviral vectors are a promising new modality for cancer treatment and clinical trials with such vectors are ongoing. Targeting these vectors to cancer cells has been the focus of research. However, even if perfect targeting were to be achieved, a vector still must effectively kill cancer cells and spread throughout the bulk of the tumor. The adenoviral E1b-19kD protein is a potent inhibitor of apoptosis and may therefore compromise the therapeutic efficacy of an adenoviral vector. In this study we have investigated if an E1b-19kD gene deletion could improve the ability of a replicating adenoviral vector to spread through and kill cancer cells. In several lung cancer cell lines an E1b-19kD-deleted virus (Ad337) induced substantially more apoptosis than did a wild-type virus (Ad309), and tumor cell survival was significantly reduced in three of four cell lines. In addition, the apoptotic effects of cisplatin or paclitaxel were augmented by Ad337, but inhibited by wild-type virus. The number of infectious virus particles in the supernatant of infected cells was increased with Ad337 compared with wild-type virus, indicating enhanced early viral release. Ad337, in contrast to Ad309, induced significantly larger plaques after infection of A549 cells. This well-described large plaque phenotype of an E1b-19kD mutant virus is likely the result of early viral release and enhanced cell-to-cell viral spread. Loss of E1b-19kD function caused only minor cell line-specific increase or decrease in viral yield. We conclude that deletion of the E1b-19kD gene may enhance the tumoricidal effects of a replicating adenoviral vector.