Individual Alpha Peak Frequency Moderates Transfer of Learning in Cognitive Remediation of Schizophrenia.

OBJECTIVE: Meta-analyses report moderate effects across cognitive remediation (CR) trials in schizophrenia. However, individual responses are variable, with some participants showing no appreciable gain in cognitive performance. Furthermore, reasons for heterogeneous outcome are undetermined. We examine the extent to which CR outcome is attributable to near learning-direct gains in trained cognitive tasks-while also exploring factors influencing far transfer of gains during training to external cognitive measures. METHOD: Thirty-seven schizophrenia outpatients were classified as CR responders and non-responders according to change in MATRICS Consensus Cognitive Battery composite score following 20 sessions of computer-based training. Metrics of near learning during training, as well as baseline demographic, clinical, cognitive, and electroencephalographic (EEG) measures, were examined as predictors of responder status. RESULTS: Significant post-training improvement in cognitive composite score (Cohen's d = .41) was observed across the sample, with n = 21 and n = 16 classified as responders and non-responders, respectively. Near learning was evidenced by significant improvement on each training exercise with practice; however, learning did not directly predict responder status. Group-wise comparison of responders and non-responders identified two factors favoring responders: higher EEG individual alpha frequency (IAF) and lower antipsychotic dosing. Tested in moderation analyses, IAF interacted with learning to predict improvement in cognitive outcome. CONCLUSION: CR outcome in schizophrenia is not directly explained by learning during training and appears to depend on latent factors influencing far transfer of trained abilities. Further understanding of factors influencing transfer of learning is needed to optimize CR efficacy.

Subcortical volumetric abnormalities in bipolar disorder.

Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case-control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen's d=-0.232; P=3.50 × 10-7) and thalamus (d=-0.148; P=4.27 × 10-3) and enlarged lateral ventricles (d=-0.260; P=3.93 × 10-5) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons.

Single-Cell Transcriptomic Analysis of Salivary Gland Endothelial Cells.

Vascular endothelial cells have important tissue-specific functions in fibrosis and regeneration. In the salivary gland, endothelial cells are required for proper development, but their roles within adult glands are largely unknown. To identify ligand-receptor interactions between endothelial cells and other cell types that may be important during fibrosis and regeneration, we used a reversible ductal ligation injury. To induce injury, a clip was applied to the primary ducts for 14 d, and to induce a regenerative response, the clip was subsequently removed for 5 d. To identify endothelial cell-produced factors, we used single-cell RNA sequencing of stromal-enriched cells from adult female submandibular and sublingual salivary glands. Transcriptional profiles of homeostatic salivary gland endothelial cells were compared to endothelial cells of other organs. Salivary gland endothelial cells expressed many unique genes and displayed the highest overlap in gene expression with other fenestrated endothelial cells from the colon, small intestine, and kidney. Comparison of the 14-d ligated, mock-ligated, and 5-d deligated stromal-enriched transcripts and lineage tracing revealed that endothelial cells retain their identity following ligation and recovery from injury. CellChat and NATMI were used to predict changes in ligand-receptor interactions from endothelial cells to other cells in response to ligation and deligation. CellChat and NATMI predicted that after ligation, interactions with fibroblasts, epithelial cells, and glial cells were increased, and following deligation, interactions with pericyte, glia, fibroblasts, and immune cells were increased. Some of the highest-ranked interactions predicted in ligated compared to mock endothelial cells were between glial cells via Col4a2-Cd93 and Jag2-Notch1, as well as epithelial cells via Pecam1-Cd38, while in deligated compared to ligated endothelial cells, the top interactions were between fibroblasts via Ntf3-Ntrk2, glial cells via Hspg2-Itgb1, and pericytes via Jam2-F11r. Understanding salivary gland endothelial cell signaling will inform future endothelial cell-based regenerative therapies.

The nonnucleoside reverse transcriptase inhibitor MIV-150 in carrageenan gel prevents rectal transmission of simian/human immunodeficiency virus infection in macaques.

Development of a microbicide that prevents rectal transmission of human immunodeficiency virus (HIV) is a vital component in reducing HIV spread. We recently demonstrated that a formulation of the nonnucleoside reverse transcriptase inhibitor (NNRTI) MIV-150 in carrageenan reduced vaginal infection of macaques with simian immunodeficiency virus SIVmac239 with HIV-1(HxB2) reverse transcriptase (SHIV-RT). Herein, we performed the first testing of MIV-150-carrageenan against rectal infection. Rhesus macaques were treated rectally with MIV-150-carrageenan or methyl cellulose (MC) placebo gel up to 4 h prior to rectal challenge with 10³ or 10(4) 50% tissue culture infective doses (TCID50) of SHIV-RT. Infection was assessed by measuring plasma virus RNA as well as T and B cell responses. MIV-150-carrageenan protected all animals challenged with 10³ TCID(50 when gel was applied either 30 min or 4 h prior to challenge, while 100% of the MC-treated animals became infected (n = 4 each; P < 0.03). Partial protection (2 of 4 animals) by MIV-150-carrageenan was observed for rectal challenge with 10-fold more virus applied 4 h after the gel. Sequencing of the RT gene from plasma virus RNA isolated at peak viremia confirmed that both of these animals (like infected MC controls) were infected with wild-type virus. Infection correlated with the development of SIV-specific T and B cell responses. MIV-150 was detected in the rectal fluids and tissues 4 h after gel application but was not detected in the blood at any time (0.5 to 24 h). These data are promising for the development of NNRTI-containing gels to prevent rectal HIV transmission.

Antibodies to cachectin/tumor necrosis factor reduce interleukin 1 beta and interleukin 6 appearance during lethal bacteremia.

Cytokines secreted in response to invading micro-organisms are important mediators of detrimental hemodynamic and metabolic changes in the host. To test whether cachectin/TNF plays a role in triggering release of other cytokines in the setting of infection, anesthetized baboons were passively immunized against systemic cachectin/TNF before infusion of a LD100 dose of live Escherichia coli. Bacteremia led to significant increases in circulating levels of cachectin/TNF, IL-1 beta, and IL-6. Although bacterial endotoxin/lipopolysaccharide is a potent stimulus for the synthesis and release of IL-1 and IL-6 in vitro, specific neutralization of cachectin/TNF in vivo with mAb pretreatment significantly attenuated both the IL-1 beta and the IL-6 responses despite fulminant overwhelming bacteremia. These data suggest that cachectin/TNF is essential for the initiation or amplification of IL-1 and IL-6 release during lethal gram-negative septic shock syndrome.

A human tumor necrosis factor p75 receptor agonist stimulates in vitro T cell proliferation but does not produce inflammation or shock in the baboon.

Tumor necrosis factor (TNF) is a potentially useful adjunct to anticancer therapies. However, the clinical utility of TNF has been limited by generalized toxicity and hypotension. Recently, studies have begun to dissect the individual proinflammatory and immunologic responses that result from TNF binding to its two cellular receptors, p55 and p75, in an attempt to develop TNF receptor agonists with reduced systemic toxicity. To evaluate a p75 receptor selective TNF mutant (p75TNF), TNF and p75TNF were administered to healthy anesthetized baboons. Intravenous infusion of the p75TNF produced none of the hemodynamic changes seen after the infusion of TNF. Infusion of p75TNF also failed to induce the plasma appearance of interleukins 6 and 8. However, p75TNF enhanced in vitro baboon thymocyte proliferation to concanavalin A, and infusion of p75TNF resulted in increased soluble p55 and p75 receptor plasma concentrations. Local skin necrosis and tissue neutrophil infiltration were seen after subcutaneous injections of TNF and p55TNF. Subcutaneous injection of p75TNF did not result in skin necrosis but did result in a modest dermal infiltration of lymphocytes and macrophages. The findings suggest that p75TNF may stimulate T cell proliferation without the systemic and local toxicity seen with TNF.

A unique family of endothelial cell polypeptide mitogens: the antigenic and receptor cross-reactivity of bovine endothelial cell growth factor, brain-derived acidic fibroblast growth factor, and eye-derived growth factor-II.

Bovine brain, hypothalamus, pituitary, and retina contain potent anionic polypeptide mitogens for endothelial cells. Immunological assays using murine monoclonal antibodies against bovine endothelial cell growth factor (ECGF) and radioreceptor assays using [125I]ECGF were performed to determine the cross-reactivity of ECGF with bovine acidic pI brain-derived fibroblast growth factor (acidic FGF) and bovine eye-derived growth factor-II [EDGF-II). We observed that acidic FGF and EDGF-II are recognized by anti-ECGF monoclonal antibodies and compete with [125I] ECGF for receptor occupancy. Furthermore, the biological activity of ECGF, acidic FGF, and EDGF-II is potentiated by the glycosaminoglycan, heparin. These results argue that ECGF, acidic FGF, and EDGF-II belong to a common family of polypeptide growth factors.

Reversible conversion of monomeric human prion protein between native and fibrilogenic conformations.

Prion propagation involves the conversion of cellular prion protein (PrPC) into a disease-specific isomer, PrPSc, shifting from a predominantly alpha-helical to beta-sheet structure. Here, conditions were established in which recombinant human PrP could switch between the native alpha conformation, characteristic of PrPC, and a compact, highly soluble, monomeric form rich in beta structure. The soluble beta form (beta-PrP) exhibited partial resistance to proteinase K digestion, characteristic of PrPSc, and was a direct precursor of fibrillar structures closely similar to those isolated from diseased brains. The conversion of PrPC to beta-PrP in suitable cellular compartments, and its subsequent stabilization by intermolecular association, provide a molecular mechanism for prion propagation.

Characterization of Cu2+-binding modes in the prion protein by visible circular dichroism and multivariate curve resolution.

Visible circular dichroism (CD) spectra from the copper(II) titration of the metal-binding region of the prion protein, residues 57-98, were analyzed using the self-modeling curve resolution method multivariate curve resolution-alternating least squares (MCR-ALS). MCR-ALS is a set of mathematical tools for estimating pure component spectra and composition profiles from mixture spectra. Model-free solutions (e.g., soft models) are produced under the assumption that pure component profiles should be nonnegative and unimodal. Optionally, equality constraints can be used when the concentration or spectrum of one or more species is known. MCR-ALS is well suited to complex biochemical systems such as the prion protein which binds multiple copper ions and thus gives rise to titration data consisting of several pure component spectra with overlapped or superimposed absorption bands. Our study reveals the number of binding modes used in the uptake of Cu(2+) by the full metal-binding region of the prion protein and their relative concentration profiles throughout the titration. The presence of a non-CD active binding mode can also be inferred. We show that MCR-ALS analysis can be initialized using empirically generated or mathematically generated pure component spectra. The use of small model peptides allows us to correlate specific Cu(2+)-binding structures to the pure component spectra.

Oxygen radical scavengers selectively inhibit interleukin 8 production in human whole blood.

The hydroxyl radical (OH.) scavenger dimethyl sulfoxide (DMSO) was found to dose-dependently inhibit interleukin 8 (IL-8) production in LPS-stimulated human whole blood. At a concentration of 1% (vol/vol), DMSO blocked IL-8 release by approximately 90% in the presence of 1 microgram/ml LPS at a 24-h time point, but did not affect cell viability or reduce the production of tumor necrosis factor (TNF), interleukin 6, or interleukin-1 beta (IL-1 beta). DMSO was found to directly inhibit IL-8 expression at the level of transcription. Furthermore, this effect was not LPS-specific, in that IL-8 production was reduced by DMSO to a similar extent upon stimulation of blood with phytohemagglutinin, aggregated immune complexes, TNF, or IL-1 beta. Other oxygen radical scavengers that have been shown to inhibit OH.-dependent reactions (dimethyl thiourea, thiourea, mannitol, and ethanol) also inhibited IL-8 production. Conversely, addition of H2O2 caused a dose-dependent stimulation of IL-8 release. These results provide evidence that reactive oxygen metabolites play an important role in the regulation of IL-8 production and suggest that reduction of IL-8 release may contribute to the beneficial effects of antioxidants in experimental models of inflammation and ischemia/reperfusion injury.

Evidence for the involvement of interleukin 6 in experimental cancer cachexia.

In this report we describe an experimental model of cachexia that fulfills the criteria of an early effect with a small tumor mass not related to the growth rate of the tumor, and progressive wasting of muscle and fat without a detectable loss of appetite. C-26.IVX is a cell line derived from murine colon-26 adenocarcinoma which retains the transplantability of the original tumor and induces true cachexia in syngeneic hosts. Evidence is presented to support a role for interleukin (IL-6) as a cachectic factor in the development of cancer cachexia in this model system. Thus, increasing levels of IL-6 in C-26.IVX-bearing mice correlate with the development of cachexia. If the primary tumors were resected, mice gained weight and the levels of IL-6 in the serum were reduced significantly. Moreover, monoclonal antibody to murine IL-6 (but not anti-tumor necrosis factor antibody) was able to significantly suppress the development of key parameters of cachexia in tumor bearing mice.

The acute splanchnic and peripheral tissue metabolic response to endotoxin in humans.

The in vivo alterations in organ-specific substrate processing and endogenous mediator production induced by endotoxin were investigated in healthy volunteers. An endotoxin bolus (20 U/kg) produced increased energy expenditure, hyperglycemia, hypoaminoacidemia, and an increase in circulating free fatty acids. These changes included increased peripheral lactate and free fatty acid output, along with increased peripheral uptake of glucose. Coordinately, there were increased splanchnic uptake of oxygen, lactate, amino acids, and free fatty acids, and increased splanchnic glucose output. There were no changes in circulating glucagon, or insulin and transient changes in epinephrine and cortisol were insufficient to explain the metabolic changes. Plasma cachectin levels peaked 90 min after the endotoxin infusion, and hepatic venous (HV) cachectin levels (peak 250 +/- 50 pg/ml) were consistently higher than arterial levels (peak 130 +/- 30 pg/ml, P less than 0.05 vs. HV). No interleukin 1 alpha or 1 beta was detected in the circulation. Circulating interleukin 6, measured by B.9 hybridoma proliferation, peaked 2 h after the endotoxin challenge (arterial, 16 +/- 2 U/ml; HV, 21 +/- 3 U/ml). The net cachectin efflux (approximately 7 micrograms) from the splanchnic organs demonstrates that these tissues are a major site for production of this cytokine. Hence, splanchnic tissues are likely influenced in a paracrine fashion by regional cachectin production and may also serve as a significant source for systemic appearance of this cytokine.

Interleukin-1 receptor blockade improves survival and hemodynamic performance in Escherichia coli septic shock, but fails to alter host responses to sublethal endotoxemia.

The present study was undertaken to evaluate the extent to which an endogenous interleukin-1 (IL-1) response contributes to the hemodynamic and metabolic consequences of sublethal endotoxemia or lethal Gram-negative septic shock. Young, healthy baboons received either a sublethal dose of lipopolysaccharide (LPS) or an LD100 of live Escherichia coli bacteria, and one half of the animals in each group were continuously infused with IL-1 receptor antagonist (IL-1ra). Plasma IL-1 beta was not detected in this model of endotoxemia. Administration of IL-1ra had only minimal effects on the modest hemodynamic and metabolic responses to sublethal endotoxemia, and did not attenuate the plasma cytokine response. In contrast, high circulating levels of IL-1 beta (range 300-800 pg/ml) were seen during lethal E. coli septic shock. IL-1ra treatment significantly attenuated the decrease in mean arterial blood pressure (MAP) (from -72 +/- 8 to -43 +/- 6 mm Hg; P less than 0.05) and cardiac output (from -0.81 +/- 0.17 to -0.48 +/- 0.15 liter/min; P less than 0.05), and significantly improved survival from 43 to 100% at 24 h (P less than 0.05). The plasma IL-1 beta and IL-6 responses to lethal E. coli septic shock were also significantly diminished by IL-1ra treatment (P less than 0.05), whereas tumor necrosis factor-alpha (TNF alpha) concentrations were unaffected. We conclude that an exaggerated systemic IL-1 beta response is characteristic of lethal E. coli septic shock, and contributes significantly to the hemodynamic and metabolic consequences of E. coli septic shock. IL-1ra can significantly attenuate the cytokine cascade and improve survival.

CpG-C ISS-ODN activation of blood-derived B cells from healthy and chronic immunodeficiency virus-infected macaques.

Cytosine-phosphate-guanine class C (CpG-C) immunostimulatory sequence oligodeoxynucleotides (ISS-ODNs) activate human B cells and dendritic cells (DCs), properties that suggest potential use as a novel adjuvant to enhance vaccine efficacy. After demonstrating that the CpG-C ISS-ODN C274 activates macaque DCs, we examined in vitro activation of macaque B cells by C274 as a prelude to evaluation of this molecule as an adjuvant in the testing of candidate human immunodeficiency virus vaccines in the rhesus macaque-simian immunodeficiency virus (SIV) model. C274 induced macaque CD20(+) B cells to proliferate more strongly than CD40 ligand or CpG-B ISS-ODN. C274 enhanced B cell survival; increased viability was most evident after 3-7 days of culture. Increased expression of CD40, CD80, and CD86 by B cells was apparent within 24 h of exposure to C274 and persisted for up to 1 week. C274-stimulated, B cell-enriched and peripheral blood mononuclear cell suspensions from naïve and immunodeficiency virus-infected monkeys secreted several cytokines [e.g., interleukin (IL)-3, IL-6, IL-12, interferon-alpha] and chemokines [e.g., monocyte chemoattractant protein-1/CC chemokine ligand 2 (CCL2), macrophage-inflammatory protein-1alpha/CCL3, IL-8/CXC chemokine ligand 8]. In comparison, exposure of macaque B cells to SIV had minimal impact on surface phenotype, despite inducing cytokine and chemokine production in cells from infected and uninfected animals. These observations emphasize the need to identify strategies to optimally boost immune function, as immunodeficiency viruses themselves only partially activate B cells and DCs. The ability of C274 to stimulate B cells and DCs in healthy and infected monkeys suggests its possible use as a broad-acting adjuvant to be applied in the rhesus macaque model for the development of preventative and therapeutic vaccines.

Antibody formation against beta-tubulin class III in response to brain trauma.

Brain trauma typically leads to neuronal damage and loss. Assuming a transient autoimmune response to debris of the damaged neurones, we have monitored serum titres of IgG and IgM antibodies to beta-tubulin class III (betaTcIII), which is almost exclusively found in neuronal cytoskeletons. In 15 out of 18 patients, the peak of the IgG or IgM antibody titre appeared in the serum within 3 weeks of a brain trauma.

Visualization of fusion activation in the Semliki Forest virus spike.

BACKGROUND: Viral spike proteins such as those of Semliki Forest virus (SFV) undergo a conformational change triggered by low pH which results in the fusion of the viral envelope with cellular membranes. The viral spike precursor of SFV is insensitive to low pH, and hence is fusion incompetent, until it is proteolytically cleaved to give the fusion competent mature form. RESULTS: Three-dimensional image reconstructions from cryo-electron micrographs were used to compare the virion structure of wild-type SFV with that of a mutant SFV in which cleavage of the spike precursor had been blocked. Upon maturation to the fusion competent form, the spike undergoes a conformational change in which copies of the polypeptide containing the fusion sequence (E1) move from peripheral to lateral positions bringing them closer together. CONCLUSIONS: This first visualization of the maturation of a viral spike protein complex suggests a mechanism for the conformational change which controls the fusion process.

Determination of microtubule polarity by cryo-electron microscopy.

BACKGROUND: Microtubules are tubular polymers of tubulin dimers, which are arranged head-to-tail in protofilaments that run lengthwise along the microtubules, giving them an overall structural polarity. Many of the functions of microtubules depend on this polarity, including directed intracellular transport and chromosome segregation during mitosis. The determination of microtubule polarity for lengthwise views of microtubules observed by electron microscopy has not previously been possible. Here, we present methods for directly determining the polarity of individual microtubules imaged by cryo-electron microscopy. RESULTS: When observed in vitreous ice by cryo-electron microscopy, microtubules with skewed protofilaments show arrowhead moiré patterns. We have used centrosome nucleated microtubules to relate the directionality of the moiré patterns to microtubule polarity. We show that the arrowheads point towards the plus end of microtubules with protofilaments having a right-handed skew, and towards the minus end of microtubules with protofilaments having a left-handed skew. We describe two methods for determining the handedness of the protofilament skew. The first method uses two or more tilted views. The second method involves analysis of the diffraction patterns of the microtubule images. CONCLUSIONS: It is now possible to determine directly the polarity of in vitro assembled microtubules from cryo-electron micrographs. This will be helpful in a number of types of studies, including studies of the three-dimensional structure of microtubules interacting with motor proteins, as knowledge of the polarity of the microtubule is essential to understand motor directionality.

Evolutionary conservation in the hepatitis B virus core structure: comparison of human and duck cores.

BACKGROUND: Hepatitis B virus is a major human pathogen which has been extensively studied, yet its structure is unknown. Cryo-electron microscopy of the viral cores expressed in Escherichia coli or isolated from infected liver provides a means for determining the structure of the hepatitis B nucleocapsid. RESULTS: Using cryo-electron microscopy and three-dimensional image reconstruction, we have determined the structures of duck and human hepatitis B virus cores and find that they have similar dimer-clustered T = 3 and T = 4 icosahedral organizations. The duck virus core protein sequence differs from the human in both length and amino acid content; however, the only significant structural differences observed are the lobes of density on the lateral edges of the projecting (distal) domain of the core protein dimer. The different cores contain varying amounts of nucleic acid, but exhibit similar contacts between the core protein and the nucleic acid. Immunoelectron microscopy of intact cores has localized two epitopes on the core surface corresponding to residues 76-84 and 129-132. CONCLUSIONS: The bacterial expression system faithfully reproduces the native hepatitis B virus core structure even in the absence of the complete viral genome. This confirms that proper assembly of the core is independent of genome packaging. Difference imaging and antibody binding map three sequence positions in the structure: the C terminus and the regions near amino acids 80 and 130. Finally, we suggest that the genome-core interactions and the base (proximal) domain of the core dimer are evolutionarily conserved whereas the projecting domain, which interacts with the envelope proteins, is more variable.

Dendritic cells and HIV infection: activating dendritic cells to boost immunity.

Dendritic cells (DCs) are white blood cells that coordinate innate and adaptive immunity. They are distributed within epithelia and mucosal-associated lymphoid tissues, positioned to entrap incoming pathogens or vaccines. Human immunodeficiency virus (HIV) and the non-human primate equivalent (SIV) exploit DCs to amplify infection, underscoring the need to harness strategies that promote presentation of virus by DCs to stimulate potent anti-viral immunity instead of virus transmission. Two main subsets of DCs need to be considered: myeloid (MDC) and plasmacytoid (PDC) subsets. Using the SIV-macaque system to advance oral vaccine research, we examined macaque PDC and MDC biology, identifying ways to activate DCs and boost antiviral immunity. Immunostimulatory oligodeoxyribonucleotides (ISS-ODNs) stimulated PDC/MDC mixtures to up-regulate co-stimulatory molecule expression and to secrete both IFN-alpha and IL-12. Additionally, ISS-ODNs augmented SIV-specific IFN-gamma responses induced by virus-bearing DCs. ISS-ODN-driven DC activation is being pursued to improve oral/nasopharyngeal mucosal vaccines and therapies against HIV.

Bcl-2 antisense oligodeoxynucleotide therapy of Epstein-Barr virus-associated lymphoproliferative disease in severe combined immunodeficient mice.

Bcl-2 is upregulated by Epstein-Barr virus (EBV) in immortalized lymphoblastoid (LCL) B cells and is expressed in the majority of EBV-associated posttransplant lymphoproliferative disorders (PTLDs). Given the antiapoptotic function and chemoprotective effects of Bcl-2, it represents a rational target for modulation using antisense oligodeoxynucleotides in Bcl-2-expressing, EBV-associated lymphoproliferative disorders. Using a fully phosphorothioated oligodeoxynucleotide targeted to the first six codons of Bcl-2, we examined the effects of Bcl-2 antisense both in vitro in LCLs and in vivo in the human/severe combined immunodeficient chimeric model of EBV-associated lymphoproliferative disorders. In vitro treatment of LCLs with Bcl-2 antisense in the presence of cationic lipid was associated with decreased expression of Bcl-2 protein, inhibition of proliferation, and stimulation of apoptotic cell death; these effects were sequence-dependent. Furthermore, treatment of LCL-bearing severe combined immunodeficient mice with Bcl-2 antisense but not control oligodeoxynucleotides completely prevented or significantly delayed the development of fatal EBV-positive lymphoproliferative disease in vivo. These studies demonstrate that Bcl-2 antisense oligodeoxynucleotides mediate sequence-dependent antitumor effects in EBV-associated B-cell lymphoproliferations both in vitro and in vivo. These findings suggest that Bcl-2 antisense therapy may represent a novel antitumor treatment strategy for EBV-associated PTLDs and other Bel-2-expressing, EBV-positive malignancies.