P1507Role of adjuvant carotid ultrasound in women undergoing stress echocardiography for the assessment of suspected angina with no previous history of coronary artery disease

Introduction

Traditional risk assessment tools classify the majority of women at low risk despite cardiovascular disease remaining the leading cause of death in women. Additionally conventional stress testing techniques have poor predictive value in women, due to unique pathophysiological mechanisms causing ischaemia in women, and the lower prevalence of obstructive CAD. The study sought to evaluate the role of adjuvant carotid ultrasound (CU) in women attending for stress echocardiography (SE).

Methods and results

415 women (Mean age 62±10 years, 28% Diabetes Mellitus, Mean BMI 28) attending for SE prospectively underwent CU, to assess Carotid Intima-media thickness (CIMT) and the presence of plaque.

47 women (11%) had inducible wall motion abnormalities, and carotid disease (CD) was present in 46% (Carotid plaque in 41%, 15% CIMT >75th percentile). Women with CD were older (65 vs 58 years, p<0.0001), more likely to have Diabetes (41% vs 21%, p=0.0001) and hypertension (67% vs 36%, p<0.01), and had higher pretest probability of CAD (59% vs 41%, p<0.0001). 40% of women classified as low Framingham, were found to have evidence of CD. Conversely, only 40% of women classified as high Framingham risk, had CD.

The positive predictive value of SE for flow-limiting CAD was 51%, but the presence of carotid plaque improved this to 71% (p<0.01). Of all clinical and test parameters, carotid plaque (p=0.001) and SE result (p=0.01) were the only independent predictors of >70% angiographic.

Conclusion

CU significantly improves the accuracy of SE alone for identifying flow-limiting disease on coronary angiography. Non-invasive assessment of subclinical atherosclerosis using CU offers an individualized disease-guided approach in women, where conventional scoring systems offer modest risk stratification.

A rare case of simultaneous pneumoperitoneum and pneumomediastinum with a review of the literature

Simultaneous pneumoperitoneum and pneumomediastinum is a rare clinical occurrence. It has been reported in the literature as a complication of various medical and dental procedures. To our knowledge, we present the first case of a non-iatrogenic and traumatic simultaneous pneumoperitoneum and pneumomediastinum in a previously independent 91-year-old man who presented to hospital with back and chest wall pain following mechanical fall from standing. A new radiological diagnosis of diverticular disease with possible perforation was made following admission. Despite appropriate management and supportive measures, the patient died 12 days after admission from a kidney injury.

Pigment epithelium-derived factor inhibits advanced glycation end-products-induced cytotoxicity in retinal pericytes

AIM

This study investigated the effects of pigment epithelium-derived factor (PEDF) on advanced glycation end-product (AGE)-induced cytotoxicity in porcine retinal pericytes and the signalling mechanism involved.

METHODS

Retinal pericytes were isolated from porcine eyes and characterized by immunocytochemistry. The effect of AGEs and PEDF on cell proliferation was determined by bromodeoxyuridine (BrdU) assay. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was analyzed by luminescence assay. Reactive oxygen species (ROS), nitric oxide (NO), superoxide dismutase (SOD) and glutathione peroxidase (GSH) were determined by biochemical assays. Induction of apoptosis was determined by caspase-3 colorimetric assay and DNA fragmentation analysis. Src activity was assessed by transient transfection analysis, and the status of Src phosphorylation at Y419 was analyzed by a competitive ELISA method.

RESULTS

AGEs significantly increased intracellular ROS generation in pericytes via NADPH oxidase and induced cell death via caspase-3 enzyme activation, whereas PEDF increased cell proliferation in a dose-dependent manner. In addition, PEDF inhibited AGE-induced ROS generation by increasing levels of SOD and GSH, and also blocked the activation of caspase-3. Furthermore, PEDF induced cell survival via the Src pathway by Src phosphorylation at Y419, as evidenced by a pharmacological inhibitor and Src mutants.

CONCLUSION

These results suggest that PEDF abrogates AGE-induced oxidative stress and apoptosis in retinal pericytes via the Src pathway, thereby suggesting that PEDF is an effective therapeutic agent for the treatment of loss of pericytes in early diabetic retinopathy.

HLA class I serotypes and cytotoxic T-lymphocyte responses among human immunodeficiency virus-1-uninfected Thai volunteers immunized with ALVAC-HIV in combination with monomeric gp120 or oligomeric gp160 protein boosting

Antigen-induced cellular immunogenicity may vary between populations due to differences in human leukocyte antigen (HLA) diversity and, hence, may play a critical role in the protection afforded by vaccines. In the setting of two, phase I/II human immunodeficiency virus-1 vaccine trials of a recombinant canarypox prime, and boosting with either recombinant monomeric gp120 or oligomeric gp160, we assessed the association between specific human leukocyte antigen (HLA) class I serotypes and the presence of cytotoxic T-lymphocyte response measured by 51Cr-release assay. HLA class I serotypes A11, A24, A33, B46, and B75 were the most common, present in 10% or more of 245 individuals studied. Forty of 187 (21.4%) Thai adults who received either ALVAC-HIV with gp120 or oligomeric gp160 or ALVAC alone had a precursor cytolytic CD8 T-cell response (pCTL). HLA-B44 was positively and significantly associated with a pCTL response (odds ratio 7.6, 95% CI: 2.7-21.2), whereas B46 was negatively associated but not robust when adjusted for multiple comparisons. Responses to Env proteins accounted for the majority (nine of 11) of pCTL activity among those persons with B44. This HLA class I serotype occurred in 9.4% of participants overall (including the placebo group), less commonly than what is reported from populations of European ancestry. These results strengthen the importance of assessing HLA class I distributions in conjunction with studies of vaccines designed to elicit cellular immunity in different populations.

Quantitative analysis of children's microactivity patterns: The Minnesota Children's Pesticide Exposure Study

The National Human Exposure Assessment Survey (NHEXAS)/Minnesota Children's Pesticide Exposure Study (MNCPES) was a population-based study designed to characterize children's exposure to residential pesticides and to evaluate the contribution of residential and children's activities to children's exposure. Families of 168 children were surveyed for residential use of pesticides and children's activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week-long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand-to-mouth and object-to-mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.

BALB/c mice bearing a transgenic IL-12 receptor beta 2 gene exhibit a nonhealing phenotype to Leishmania major infection despite intact IL-12 signaling

In BALB/c mice infected with Leishmania major, early secretion of IL-4 leads to a Th2-type response and nonhealing. We explored the role of IL-4-induced down-regulation of the IL-12Rbeta2 chain in the establishment of this Th2 response. First, we showed that the draining lymph nodes of resistant C57BL/6 mice infected with L. major were enriched in CD4+/IL-12Rbeta2 chain+ cells producing IFN-gamma. Next, we demonstrated that BALB/c background mice bearing an IL-12Rbeta2-chain transgene manifested a nonhealing phenotype similar to wild-type littermates despite the persistence of their ability to undergo STAT4 activation. Finally, we found that such transgenic mice display more severe infection than wild-type littermates when treated with IL-12 7 days after infection, and under this condition, the mice display increased Leishmania Ag-induced IL-4 secretion. These studies indicate that although CD4+/IL-12Rbeta2 chain+ T cells are important components of the Th1 response, maintenance of IL-12Rbeta2 chain expression is not sufficient to change a Th2 response to a Th1 response in vivo and thus to allow BALB/c mice to heal L. major infection.

The potency and durability of DNA- and protein-based vaccines against Leishmania major evaluated using low-dose, intradermal challenge

DNA- and protein- based vaccines against cutaneous leishmaniasis due to Leishmania major were evaluated using a challenge model that more closely reproduces the pathology and immunity associated with sand fly-transmitted infection. C57BL/6 mice were vaccinated s.c. with a mixture of plasmid DNAs encoding the Leishmania Ags LACK, LmSTI1, and TSA (AgDNA), or with autoclaved L. major promastigotes (ALM) plus rIL-12, and the mice were challenged by inoculation of 100 metacyclic promastigotes in the ear dermis. When challenged at 2 wk postvaccination, mice receiving AgDNA or ALM/rIL-12 were completely protected against the development of dermal lesions, and both groups had a 100-fold reduction in peak dermal parasite loads compared with controls. When challenged at 12 wk, mice vaccinated with ALM/rIL-12 maintained partial protection against dermal lesions and their parasite loads were no longer significantly reduced, whereas the mice vaccinated with AgDNA remained completely protected and had a 1000-fold reduction in dermal parasite loads. Mice vaccinated with AgDNA also harbored few, if any, parasites in the skin during the chronic phase, and their ability to transmit L. major to vector sand flies was completely abrogated. The durable protection in mice vaccinated with AgDNA was associated with the recruitment of both CD8(+) and CD4(+) T cells to the site of intradermal challenge and with IFN-gamma production by CD8(+) T cells in lymph nodes draining the challenge site. These data suggest that under conditions of natural challenge, DNA vaccination has the capacity to confer complete protection against cutaneous leishmaniasis and to prevent the establishment of infection reservoirs.

Yeast exocytic v-SNAREs confer endocytosis

In yeast, homologues of the synaptobrevin/VAMP family of v-SNAREs (Snc1 and Snc2) confer the docking and fusion of secretory vesicles at the cell surface. As no v-SNARE has been shown to confer endocytosis, we examined whether yeast lacking the SNC genes, or possessing a temperature-sensitive allele of SNC1 (SNC1(ala43)), are deficient in the endocytic uptake of components from the cell surface. We found that both SNC and temperature-shifted SNC1(ala43) yeast are deficient in their ability to deliver the soluble dye FM4-64 to the vacuole. Under conditions in which vesicles accumulate, FM4-64 stained primarily the cytoplasm as well as fragmented vacuoles. In addition, alpha-factor-stimulated endocytosis of the alpha-factor receptor, Ste2, was fully blocked, as evidenced using a Ste2-green fluorescent protein fusion protein as well as metabolic labeling studies. This suggests a direct role for Snc v-SNAREs in the retrieval of membrane proteins from the cell surface. Moreover, this idea is supported by genetic and physical data that demonstrate functional interactions with t-SNAREs that confer endosomal transport (e.g., Tlg1,2). Notably, Snc1(ala43) was found to be nonfunctional in cells lacking Tlg1 or Tlg2. Thus, we propose that synaptobrevin/VAMP family members are engaged in anterograde and retrograde protein sorting steps between the Golgi and the plasma membrane.

DNA vaccines: a key for inducing long-term cellular immunity

Over the past few years, major advances in several areas of immunology have provided a foundation for the rational design of vaccines against diseases requiring cellular immunity. Among these advances are the cellular mechanisms by which DNA vaccines can sustain long-term humoral and cellular immunity.

The role of antigen and IL-12 in sustaining Th1 memory cells in vivo: IL-12 is required to maintain memory/effector Th1 cells sufficient to mediate protection to an infectious parasite challenge

IL-12 plays a central role in both the induction and magnitude of a primary Th1 response. A critical question in designing vaccines for diseases requiring Th1 immunity such as Mycobacterium tuberculosis and Leishmania major is the requirements to sustain memory/effector Th1 cells in vivo. This report examines the role of IL-12 and antigen in sustaining Th1 responses sufficient for protective immunity to L. major after vaccination with LACK protein (LP) plus rIL-12 and LACK DNA. It shows that, after initial vaccination with LP plus rIL-12, supplemental boosting with either LP or rIL-12 is necessary but not sufficient to fully sustain long-term Th1 immunity. Moreover, endogenous IL-12 is also shown to be required for the induction, maintenance, and effector phase of the Th1 response after LACK DNA vaccination. Finally, IL-12 is required to sustain Th1 cells and control parasite growth in susceptible and resistant strains of mice during primary and secondary infection. Taken together, these data show that IL-12 is essential to sustain a sufficient number of memory/effector Th1 cells generated in vivo to mediate long-term protection to an intracellular pathogen.

Requirements for the maintenance of Th1 immunity in vivo following DNA vaccination: a potential immunoregulatory role for CD8+ T cells

Protective immunity against Leishmania major generated by DNA encoding the LACK (Leishmania homologue of receptor for activated C kinase) Ag has been shown to be more durable than vaccination with LACK protein plus IL-12. One mechanism to account for this may be the selective ability of DNA vaccination to induce CD8+ IFN-gamma-producing T cells. In this regard, we previously reported that depletion of CD8+ T cells in LACK DNA-vaccinated mice abrogated protection when infectious challenge was done 2 wk postvaccination. In this study, we extend these findings to study the mechanism by which CD8+ T cells induced by LACK DNA vaccination mediate both short- and long-term protective immunity against L. major. Mice vaccinated with LACK DNA and depleted of CD8+ T cells at the time of vaccination or infection were unable to control infection when challenge was done 2 or 12 wk postvaccination. Remarkably, it was noted that depletion of CD8+ T cells in LACK DNA-vaccinated mice was associated with a striking decrease in the frequency of LACK-specific CD4+ IFN-gamma-producing T cells both before and after infection. Moreover, data are presented to suggest a mechanism by which CD8+ T cells exert this regulatory role. Taken together, these data provide additional insight into how Th1 cells are generated and sustained in vivo and suggest a potentially novel immunoregulatory role for CD8+ T cells following DNA vaccination.

DNA vaccines: immunology, application, and optimization*

The development and widespread use of vaccines against infectious agents have been a great triumph of medical science. One reason for the success of currently available vaccines is that they are capable of inducing long-lived antibody responses, which are the principal agents of immune protection against most viruses and bacteria. Despite these successes, vaccination against intracellular organisms that require cell-mediated immunity, such as the agents of tuberculosis, malaria, leishmaniasis, and human immunodeficiency virus infection, are either not available or not uniformly effective. Owing to the substantial morbidity and mortality associated with these diseases worldwide, an understanding of the mechanisms involved in generating long-lived cellular immune responses has tremendous practical importance. For these reasons, a new form of vaccination, using DNA that contains the gene for the antigen of interest, is under intensive investigation, because it can engender both humoral and cellular immune responses. This review focuses on the mechanisms by which DNA vaccines elicit immune responses. In addition, a list of potential applications in a variety of preclinical models is provided.

House dust levels of selected insecticides and a herbicide measured by the EL and LWW samplers and comparisons to hand rinses and urine metabolites

During the Minnesota Children's Pesticide Exposure Study (MNCPES), comparisons were made between the insecticide/herbicide loadings obtained with two household dust/insecticide or herbicide samplers: the Edwards and Lioy (EL) press sampler (used for dust collection from carpets or other surfaces) and the Lioy, Waimnan and Weisel (LWW) surface wipe sampler. The results were compared with hand rinse levels, and urine metabolite levels obtained from 102 children (ages 3-13). All measurements were made during a 1-week sampling period, and information was obtained on household pesticide use and each child's activities. Of the homes, <5% had recent spot uses of a pesticide but none had recent general applications. The analyses focused primarily on atrazine (a herbicide), and malathion, diazinon, and chlorpyrifos (insecticides). Metabolites were measured for atrazine, malathion and chlorpyrifos. The atrazine levels obtained using the EL indicate that this compound was transported into the home by an unquantified transport mechanism (e.g. tracking of soil). Two malathion hand rinse values exceeded >170 ng/cm2, suggesting that since indoor surface levels were low, these children had other sources of exposure. Atrazine, chlorpyrifos and malathion were detectable in >30% of the homes by the EL, LWW or hand rinse. Only chlorpyrifos had detectable levels in > or = 50% of the samples for all types, i.e. compound or metabolite, which is consistent with it being a common household pesticide. The median (and maximum) chlorpyrifos levels for the EL surface, EL carpet, LWW surface (two rooms), hand rinse, and urine metabolites were: 0.07 (32.6) ng/cm2; 0.07 (44.5) ng/cm2; 0.34 (3.64) ng/cm2; 0.42 (14.4) ng/cm2; 0.03 (2.14) ng/hand and 6.9 (59.0) microg/g, respectively. A strong correlation was found for chlorpyrifos between the EL surface and carpet samples. Chlorpyrifos levels detected by LWW had a different distribution and concentration range than the EL, indicating that it collected more than the surface dislodgeable insecticide. EL was directly comparable to the hand rinse or urine levels, but only the LWW had a weak correlation with hand rinse levels, suggesting that the children had other sources of chlorpyrifos exposure. Thus, mechanistic exposure studies are needed to more accurately establish exposure dose relationships in residential settings.

Vaccine requirements for sustained cellular immunity to an intracellular parasitic infection

The humoral immunity induced by many viral and bacterial vaccines mediates protection that is maintained over a long period of time. In contrast, for other intracellular infections (such as with Leishmania major or Mycobacterium tuberculosis) for which cell-mediated immunity is required for protection, the mechanisms for developing durable responses after vaccination have not been well defined. Here we demonstrate that vaccination with plasmid DNA encoding a specific leishmanial antigen is more effective than leishmanial protein plus recombinant IL-12 in eliciting long-term immunity capable of controlling L. major infection. We also show that leishmanial protein plus IL-12 DNA produces an immunity that lasts much longer than does immunity elicited by leishmanial protein plus IL-12 protein, indicating that the persistence of IL-12 may be the essential determinant in maintaining durable cell-mediated immune responses for an intracellular parasitic infection.

CD40 ligand/trimer DNA enhances both humoral and cellular immune responses and induces protective immunity to infectious and tumor challenge

CD40/CD40 ligand interactions have a central role in the induction of both humoral and cellular immunity. In this study, we examined whether a plasmid expressing CD40 ligand/trimer (CD40LT) could enhance immune responses in vivo. BALB/c mice were injected with plasmid expressing beta-galactosidase DNA with or without CD40LT DNA or IL-12 DNA, and immune responses were assessed. Mice vaccinated with beta-gal DNA plus CD40LT DNA or IL-12 DNA had a striking increase in Ag-specific production of IFN-gamma, cytolytic T cell activity, and IgG2a Ab. The mechanism by which CD40LT DNA enhanced these responses was further assessed by treating vaccinated mice with anti-IL-12 mAb or CTLA-4 Ig (CTLA4Ig). Production of IFN-gamma and CTL activity was abrogated by these treatments, suggesting that CD40LT DNA was mediating its effects on IFN-gamma and CTL activity through induction of IL-12 and enhancement of B7 expression, respectively. Physiologic relevance for the ability of CD40LT DNA to enhance immune responses by the aforementioned pathways was shown in two in vivo models. First, with regard to CTL activity, mice vaccinated with CD40LT DNA did not develop metastatic tumor following challenge with lethal dose of tumor. Moreover, in a mouse model requiring IL-12-dependent production of IFN-gamma, mice vaccinated with soluble Leishmania Ag and CD40LT DNA were able to control infection with Leishmania major. These data suggest that CD40LT DNA could be a useful vaccine adjuvant for diseases requiring cellular and/or humoral immunity.

Accumulation of chlorpyrifos on residential surfaces and toys accessible to children

Quantitative examination of major pathways and routes of exposure to pesticides is essential for determining human risk. The current study was conducted in two apartments and examines the accumulation of the pesticide chlorpyrifos in childrens' toys after the time suggested for reentry after application. It has been established for the first time that a semivolatile pesticide will accumulate on and in toys and other sorbant surfaces in a home via a two-phase physical process that continues for at least 2 weeks postapplication. A summation of the above for a 3-6-year-old child yielded an estimated nondietary total dose of 208 microg/kg/day. Potential exposure from the inhalation pathway was negligible, while dermal and nondietary oral doses from playing with toys contributed to 39 and 61% of the total dose, respectively. If children with high frequency mouthing behavior are considered as candidates for acute exposure to chlorpyrifos residues, the estimated acute dose could be as high as 356 microg/kg/day. Routine reapplication of pesticides could lead to continued accumulation in toys and other sorbant surfaces, e.g., pillows, with large sorbant reservoirs, which can become a long-term source of exposure to a child. Estimates of a child's nondietary exposure to chlorpyrifos associated with toys and other sorbant surfaces for a period of 1 week following application appear to be of public health concern, and studies of actual childhood exposure from this pathway are warranted in the home environment. The above information should be used to determine if current procedures for postapplication reentry are sufficient and to evaluate the need for procedures to store frequently used household toys, pillows, and other sorbant objects during insecticidal application.

Vector magnitude using orthogonal ECG leads during ventricular fibrillation is associated with defibrillation outcome

Random fluctuations of ventricular fibrillation (VF) affect defibrillation; in addition, the heart is more susceptible to defibrillation at a higher absolute VF voltage (AVFV). Shocks delivered at higher AVFV waveforms from a single lead of the electrocardiogram (ECG) are more effective than conventional shocks. The authors investigated a new sensing method using multiple leads for better representation of the depolarization state of the heart. In this non-thoracotomy defibrillation study, a vector waveform derived from three orthogonal surface leads X, Y, and Z was analyzed in real time using two distinct defibrillation lead configurations, P1: RV-coil electrode (-) <--> (SVC-coil electrode + SCP) (+); and P2: RV-coil electrode (+) <--> (SVC-coil electrode + SCP) (-), where (-) represents cathode and (+) anode for the first phase of biphasic shock (RV = right ventricle, SVC = superior vena cava, SCP = subcutaneous patch). A PC-based closed-loop waveform-processing system, the peak-shock method (PSM), was developed to analyze the vector waveforms and trigger a biphasic shock at an AVFV peak. In using this defibrillation technique, an empirical threshold was applied to a weight function consisting of short-term and long-term moving averages of the vector VF waveform. A total of 340 shock trials in nine canine studies resulted in a significantly higher defibrillation success rate for the PSM compared with the conventional random-shock method (RSM), which involved shocking after a fixed VF time (54% for the PSM versus 42% for the RSM, p < 0.03). This further confirms that a susceptible period for defibrillation occurs during VF. The hardware/software design satisfied the requirements for processing the VF vector waveform in real time, and with the help of signal-processing techniques the high VF voltage could be detected at it occurred in real time. In addition, the P2 defibrillation lead configuration was significantly better than the P1 (p < 0.006).

Accumulation of chlorpyrifos on residential surfaces and toys accessible to children

Quantitative examination of major pathways and routes of exposure to pesticides is essential for determining human risk. The current study was conducted in two apartments and examines the accumulation of the pesticide chlorpyrifos in childrens' toys after the time suggested for reentry after application. It has been established for the first time that a semivolatile pesticide will accumulate on and in toys and other sorbant surfaces in a home via a two-phase physical process that continues for at least 2 weeks postapplication. A summation of the above for a 3-6-year-old child yielded an estimated nondietary total dose of 208 microg/kg/day. Potential exposure from the inhalation pathway was negligible, while dermal and nondietary oral doses from playing with toys contributed to 39 and 61% of the total dose, respectively. If children with high frequency mouthing behavior are considered as candidates for acute exposure to chlorpyrifos residues, the estimated acute dose could be as high as 356 microg/kg/day. Routine reapplication of pesticides could lead to continued accumulation in toys and other sorbant surfaces, e.g., pillows, with large sorbant reservoirs, which can become a long-term source of exposure to a child. Estimates of a child's nondietary exposure to chlorpyrifos associated with toys and other sorbant surfaces for a period of 1 week following application appear to be of public health concern, and studies of actual childhood exposure from this pathway are warranted in the home environment. The above information should be used to determine if current procedures for postapplication reentry are sufficient and to evaluate the need for procedures to store frequently used household toys, pillows, and other sorbant objects during insecticidal application.

Vaccination with DNA encoding the immunodominant LACK parasite antigen confers protective immunity to mice infected with Leishmania major

To determine whether DNA immunization could elicit protective immunity to Leishmania major in susceptible BALB/c mice, cDNA for the cloned Leishmania antigen LACK was inserted into a euykaryotic expression vector downstream to the cytomegalovirus promoter. Susceptible BALB/c mice were then vaccinated subcutaneously with LACK DNA and challenged with L. major promastigotes. We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein. Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12. The immunity conferred by LACK DNA was durable insofar as mice challenged 5 wk after vaccination were still protected, and the infection was controlled for at least 20 wk after challenge. In addition, the ability of mice to control infection at sites distant to the site of vaccination suggests that systemic protection was achieved by LACK DNA vaccination. The control of disease progression and parasitic burden in mice vaccinated with LACK DNA was associated with enhancement of antigen-specific interferon-gamma (IFN-gamma) production. Moreover, both the enhancement of IFN-gamma production and the protective immune response induced by LACK DNA vaccination was IL-12 dependent. Unexpectedly, depletion of CD8(+) T cells at the time of vaccination or infection also abolished the protective response induced by LACK DNA vaccination, suggesting a role for CD8(+) T cells in DNA vaccine induced protection to L. major. Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.