Rat stomach ECL cells: mode of activation of histidine decarboxylase

Histidine decarboxylase (HDC) occurs in ECL cells in the oxyntic mucosa of rat stomach. It is activated by gastrin. Refeeding of fasted rats or treatment with the proton pump inhibitor omeprazole promptly raised the serum gastrin concentration and consequently the HDC activity and the HDC protein content of the oxyntic mucosa. The food- and omeprazole-induced increase in HDC mRNA expression in the oxyntic mucosa was modest by comparison. Blockade of translation (cycloheximide) but not transcription (actinomycin D) prevented the postprandial rise in HDC activity. The half-life of HDC activity (after blockade of translation) was 94 min in omeprazole-treated rats and 55 min in fasted controls. The rate of enzyme synthesis was estimated to be 15 times higher in omeprazole-treated rats than in fasted controls. Inhibition of histamine uptake into ECL-cell granules by reserpine, a blocker of the vesicular monoamine transporter type-2, lowered the HDC activity and prevented the gastrin-induced HDC activation. We suggest that HDC activation reflects enhanced transcription, translation and/or posttranslational enzyme activation as well as stabilization, and that a high cytosolic histamine concentration suppresses HDC activation.

Provision of anaesthesia for porcine cardiac transplantation at the veterinary school in Trinidad and Tobago

A successful heterotopic cardiac transplantation was performed between sibling female Yorkshire Juvenile swine. Adequate pre-medication with azaperone and a smooth induction were ensured for both pigs, which were anaesthetized simultaneously with sodium thiopentone followed by endotracheal intubation and intermittent positive pressure ventilation. Inhalation anaesthetic agents were used for maintenance, neuromuscular blockade was achieved with cisatracurium and both fentanyl and tramadol were used to provide analgesia. Invasive monitoring was used in both the donor and recipient. Central venous pressure (CVP) was maintained at > 10 cm H2O and mean arterial pressure (MAP) > 60 mmHg. Heparin was injected during the surgical dissection of the heart in the donor to prevent coronary thrombosis and prior to aortic side clamping for end-to-side anastomosis of the donor heart in the recipient abdomen. After transplantation, the cardiovascular parameters of the recipient showed a MAP of 85-105 mmHg and a CVP of 8-10 cm H2O while echocardiography of the transplanted heart confirmed an ejection fraction (EF) of 80%. A functional anaesthetic team was assembled and trained to provide anaesthesia for porcine cardiac transplantation. The transplanted heart suffered pump failure after 69 days and was excised for performance of tissue analysis.

Selective inhibitors of the osteoblast proteasome stimulate bone formation in vivo and in vitro

We have found that the ubiquitin-proteasome pathway exerts exquisite control of osteoblast differentiation and bone formation in vitro and in vivo in rodents. Structurally different inhibitors that bind to specific catalytic beta subunits of the 20S proteasome stimulated bone formation in bone organ cultures in concentrations as low as 10 nM. When administered systemically to mice, the proteasome inhibitors epoxomicin and proteasome inhibitor-1 increased bone volume and bone formation rates over 70% after only 5 days of treatment. Since the ubiquitin-proteasome pathway has been shown to modulate expression of the Drosophila homologue of the bone morphogenetic protein-2 and -4 (BMP-2 and BMP-4) genes, we examined the effects of noggin, an endogenous inhibitor of BMP-2 and BMP-4 on bone formation stimulated by these compounds and found that it was abrogated. These compounds increased BMP-2 but not BMP-4 or BMP-6 mRNA expression in osteoblastic cells, suggesting that BMP-2 was responsible for the observed bone formation that was inhibited by noggin. We show proteasome inhibitors regulate BMP-2 gene expression at least in part through inhibiting the proteolytic processing of Gli3 protein. Our results suggest that the ubiquitin-proteasome machinery regulates osteoblast differentiation and bone formation and that inhibition of specific components of this system may be useful therapeutically in common diseases of bone loss.

Genetic and physical mapping of Pi5(t), a locus associated with broad-spectrum resistance to rice blast

To gain an understanding of the molecular basis for resistance to rice blast (Magnaporthe grisea), we have initiated a project to clone Pi5(t), a locus associated with broad-spectrum resistance to diverse blast isolates. AFLP-derived markers linked to Pi5(t)-mediated resistance were isolated using bulked segregant analysis of F(2) populations generated by crossing three recombinant inbred lines (RILs), RIL125, RIL249, and RIL260 with the susceptible line CO39. The most tightly linked AFLP marker, S04G03, was positioned on chromosome 9 of the fingerprint-based physical map of Nipponbare, a well-characterized rice genotype. Flanking BAC-based Nipponbare markers were generated for saturation mapping using four populations, the three initial RILs and an additional one derived from a cross between M202 and RIL260. A BIBAC (binary BAC) library was constructed from RIL260. Using these resources Pi5(t) was mapped to a 170-kb interval, and a contiguous set of BIBAC clones spanning this region was constructed. It had previously been suggested that Pi3(t) and Pi5(t) might be allelic, due to their identical resistance spectrum and tight linkage. We therefore compared genomic regions for lines containing Pi3(t) using the Pi5(t)-linked markers. DNA gel-blot analyses indicated that the region around Pi3(t) is identical to that of Pi5(t), suggesting that Pi3(t) and Pi5(t) are the same resistance gene.

Role of cytokines in the gene expression of amyloid beta-protein precursor: identification of a 5'-UTR-binding nuclear factor and its implications in Alzheimer's disease

One of the major neuropathological characteristics of Alzheimer's disease (AD) is the brain depositions of senile plaques that are mainly composed of toxic amyloid beta-peptide (Abeta), which is generated from a family of Abeta containing precursor proteins (AbetaPP; 695-770 amino acids). The role of cytokines and growth factors has been implicated in the pathogenesis of AD. Our goal is to determine the mode of action of cytokines on the regulation of betaPP gene expression. Here we studied the effect of different cytokines on the activity of 5'-untranslated region (5'-UTR) of betaPP mRNA in human astrocytic cells (U-373). We compared betaPP-5'-UTR activity in the presence of interleukin-1 (IL-1alpha and IL-1beta), transforming growth factor (TGF-beta1) and tumor necrosis factor TNF-alpha1. The astrocytic cells, which were treated separately with these agents, were transfected with either the vector (pSV2CAT) or pSV2UTR-CAT construct containing 90 bp of AbetaPP 5'-UTR +54 to 144 bp). This region was cloned upstream of a reporter chloramphenicol acetyl transferase gene (CAT). Our results indicate that the treatment of pSV2UTR-CAT-transfected cells with either IL-1alpha, IL-1beta, TGF-beta1 or TNF-alpha1 stimulated reporter gene activity in a factor-specific manner. This was consistent with their effects on elevating AbetaPP protein levels. Transfection of the same cells with the pSV2CAT vector lacking 5'-UTR resulted in a reduced reporter gene activity with all treatments studied. DNA-gel shift experiments indicate that the 54/144 region binds to a nuclear protein(s) in a cell type specific manner. These results suggest that 5'-UTR of the AbetaPP gene can respond to the stimulation of different cytokines, which likely regulate AbetaPP transcription and translation via regulatory elements present in the AbetaPP promoter and in 5'-UTR, respectively. The characterization of AbetaPP regulatory elements, including the 5'-UTR, will accelerate the development of novel agents against new targets for AD.

Synthesis, characterization and in vitro release of 5-aminosalicylic acid and 5-acetyl aminosalicylic acid of polyanhydride--P(CBFAS)

A novel polyanhydride, poly[(5-carboxybutyl formamide)-2-acetyl salicylic anhydride] (P(CBFAS)), with 5-aminosalicylic acid (5-ASA) incorporated into the polymer backbone was synthesized and characterized by infrared, (1)H-nuclear magnetic resonance, differential scanning calorimetry, vapor pressure osmometry, etc. The polyanhydride was subjected to degradation and simultaneously released 5-ASA and its derivative 5-acetyl aminosalicylic acid (5-acetyl ASA) in vitro under various conditions. The factors influencing the release profiles of 5-ASA and 5-acetyl ASA, including polymer molecular weights, pH value, enzyme and rat gastrointestinal contents, were examined. The results showed that the release rate of 5-ASA and 5-acetyl ASA increases with increasing pH value and with decreasing molecular weights. In PBS (pH 8.0, 37 degrees C) total ASA released was 8.0% for P(CBFAS)(1) (Mn 10770) in 13 h, but only 1.1 and 2.6% at pH 2.0 and 6.5, respectively. Enzymes including pepsin and trypsin, as well as rat gastric and jejunum contents had little effect on the release rate of 5-ASA and 5-acetyl ASA at pH 2.0 and 6.5 (less than 4% in 13 h). However, the release rate of 5-ASA and 5-acetyl ASA was much fast in PBS(pH 8.0) containing 5% of cecal contents, the total ASA released was 13.6% for the polymer in 13 h. Considering the high drug loading of the polymer (50.2% of 5-ASA moieties in the backbones) and the degradation characters, it is possible to reach high local concentration of 5-ASA in the colon site via oral administration. Therefore, P(CBFAS) may be potentially useful in the colon specific delivery of 5-ASA.

Gaseous nitrogen loss from temperate perennial grass and clover dairy pastures in south-eastern Australia

The use of nitrogen (N) fertiliser on dairy pastures in south-eastern Australia has increased exponentially over the past 15 years. Concerns have been raised about the economic and environmental impact of N loss through volatilisation and denitrification. Emissions of NH3, N2, and N2O were measured for 3 years in the 4 different seasons from a grazed grass/clover pasture, with or without 200 kg N fertiliser/ha, applied as ammonium nitrate and urea.Nitrogen-fertilised treatments lost significantly more N than the control treatments in all cases. More NH3 was lost from urea-fertilised treatments than from either the control or ammonium nitrate treatments, whereas ammonium nitrate treatments lost significantly more N through denitrification than the control or urea treatments in all seasons, except for summer. More NH3 was lost in summer than in the other seasons, whereas denitrification and N2O losses were highest in winter and lowest in summer. The total annual NH3 loss from the control, ammonium nitrate, and urea treatments averaged 17, 32, and 57 kg N/ha.year, respectively. Annual denitrification losses were estimated at around 6, 15, and 13 kg N/ha.year for the control, ammonium nitrate, and urea treatments, respectively. Total gaseous N losses were estimated to be 23, 47, and 70 kg N/ha.year from the control, ammonium nitrate, and urea treatments respectively.Although the use of ammonium nitrate fertiliser would significantly reduce NH3 volatilisation losses in summer, this fertiliser costs 45% more per unit N than urea, so there is no economic justification for recommending its use over urea for the other seasons. However, the use of urea during the cooler, wetter months may result in significantly less denitrification loss. The results are discussed in terms of potential management strategies to improve fertiliser efficiency and reduce adverse effects on the environment.

The influence of phorbol ester on the effect of tamoxifen in breast cancer cells

To investigate the correlation between the activity of kinases in the growth factor signal transduction pathway and the development of resistance of breast cancer to tamoxifen, reporter gene regulated by the regulating fragment of CCD1 was transfected into the MCF-7 cells, and the influence of tamoxifen on the reporter gene expression was examined under different conditions of TPA treatment. Our results showed that the reporter gene expression was inhibited by tamoxifen and promoted by TPA. Furthermore, tamoxifen exerts an agonist effect on the reporter gene expression when the cells was treated by TPA previously for 12 h. It is concluded that TPA could induce estrogen-like effect of tamoxifen on estrogen receptor positive breast cancer cells and it may be one of the mechanisms responsible for the development of tamoxifen resistance.

cDNA microarray analysis of changes in gene expression induced by neuronal hypoxia in vitro

We used cDNA microarray gene expression profiling to characterize the transcriptional response to exposure of cultured mouse cerebral cortical neurons to hypoxia for 24 hr. Of 11,200 genes examined, 1,405 (12.5%) were induced or repressed at least 1.5-fold, whereas 26 known genes were induced and 20 known genes were repressed at least 2.5-fold. The most strongly induced genes included genes coding for endoplasmic reticulum proteins (Ero1L/Giig11, Sac1p, Ddit3/Gadd153), proteins involved in ubiquitination (Arih2, P4hb), proteins induced by hypoxia in non-neuronal systems (Gpi1, Aldo1, Anxa2, Hig1), and proteins that might promote cell death (Gas5, Egr1, Ndr1, Vdac2). These findings reinforce the importance of endoplasmic reticulum-based mechanisms and of protein-ubiquitination pathways in the neuronal response to hypoxia.

Effect of transcutaneous immunization with co-administered antigen and cholera toxin on systemic and mucosal antibody responses in sheep

Direct application of antigens to skin together with an adjuvant, a procedure called transcutaneous immunization (TCI), can induce systemic immune responses in mice, humans, cats and dogs. In previous studies we found that cholera toxin (CT) applied topically on unbroken skin induces systemic antibody and lymphocyte proliferative responses in sheep. The current study examined whether concurrent administration of CT and tetanus toxoid (TT) delivered transcutaneously could induce specific antibody responses to both antigens in sheep. Antibodies to both TT and CT were induced by TCI although antibody titres in serum to TT were higher in sheep receiving TT plus alum by intramuscular injection (n=5) than TT plus CT by TCI (n=5). The ratio of IgG1/IgG2 antibody to TT in serum was near unity, and the route of immunization, TCI versus injection, did not influence this ratio. In contrast, the ratio of IgG1/IgG2 antibody differed significantly between the two antigens, TT and CT, delivered by TCI, with a higher proportion of IgG1 antibody in serum to CT than TT. Antibody to TT was detected in lung washes from TCI and injection groups, with IgG1 predominating over IgG2 in both groups. IgA antibodies to CT and TT were detected in sera of CT and TT-immunized groups respectively but in lung washes IgA antibody to TT was detected only in the injection group. Results show that TCI induced systemic antibody responses to CT and the co-administered antigen TT, whereas no evidence was obtained for mucosal IgA responses following TCI.

Developmental expression of the beta-amyloid precursor protein and heat-shock protein 70 in the cerebral hemisphere region of the rat brain

Alzheimer's disease (AD) is characterized by depositions of the amyloid beta protein (A beta) in the brain in the form of extracellular plaques and cerebrovascular amyloid. A beta (approximately 4 kDa) is derived from a family of large (approximately 110 kDa) beta-amyloid precursor proteins (APP), which are integral membrane glycoproteins. Although a connection between AD and alcoholism has recently been suggested, this relationship has not been explored at the molecular level. Our hypothesis is that APP has a role in brain development and that abnormal APP levels may be involved in dementia associated with AD and alcoholism. We compared the profile of total APP levels between ethanol naïve alcohol-preferring (P) and alcohol-nonpreferring (NP) rats. We also investigated the possibility that APP levels can be regulated in an age-dependent manner in young rats. We studied the distribution of two proteins in the cerebral hemisphere region of the rat brain at various developmental periods. Six groups composed of the following different ages of rats were used: 7, 14, 21, 36, 43, and 78 (postnatal) days. Cell extracts from different regions of the brain were subjected to Western immunoblotting using mAb22C11. Our results suggest that levels of high-molecular-weight APP bands were greater in brain extracts from 7-day-old P rats than in other samples tested, and that the distribution of APP levels was more uneven in brain extracts from different ages of P than from NP rats. These initial results suggest that APP may play an important role in the early development of the rat brain and the alcohol-preferring trait may influence APP processing in the developing brain.

Nicotine reduces the secretion of Alzheimer's beta-amyloid precursor protein containing beta-amyloid peptide in the rat without altering synaptic proteins

Alzheimer's disease (AD) is characterized by cerebrovascular deposition of the amyloid beta-peptide (A beta), which is derived from a larger beta-amyloid precursor protein (beta APP). Altered metabolism of beta APP, resulting in increased A beta production, appears central in the neuropathology of AD. The processing of the holoprotein beta APP by different "secretase" enzymes results in three major carboxyl-truncated species. One species, which results from the cleavage of beta APP by gamma-secretase, is secreted into the cerebrospinal fluid (CSF) and is called sAPP gamma as it contains an intact A beta domain. Moreover, AD is characterized by cholinergic dysfunction and the loss of synaptic proteins. Reports of an inverse relation between nicotine intake, due to cigarette smoking, and the incidence of AD prompted us to investigate the effects of nicotine on beta APP processing and synaptic proteins in rats and in cell culture. Nicotine, 1 and 8 mg/kg/day, doses commensurate with cigarette smoking, and a higher but well tolerated dose, respectively, was administered over 14 days to rats. Levels of sAPP in the CSF sample were evaluated by Western blot analysis. The higher dose significantly increased levels of total sAPP; however, both doses significantly reduced sAPP gamma, which contains the amyloidogenic portion of A beta. These actions were blocked by nicotinic receptor antagonism. Nicotinic antagonists alone had no effect on either total sAPP or sAPP gamma levels in CSF. Nicotine did not significantly change the intracellular levels of total beta APP in rat brain extracts, which is consistent with neuronal cell culture data. Similarly, levels of vesicular protein, such as synaptophysin, and presynaptic terminal protein SNAP-25 were unaffected by nicotine treatment both in vivo and in cell culture experiments. Taken together, these results suggest that nicotine modifies beta APP processing away from the formation of potentially amyloidogenic products, without altering the levels of synaptic proteins, and that this can potentially offer therapeutic potential for Alzheimer's disease.

Control of secretion from rat stomach ECL cells in situ and in primary culture

The acid-producing part of the stomach is rich in peptide-hormone-producing endocrine/paracrine cells of different types. In birds and all mammals studied, ECL cells constitute the quantitatively predominant endocrine cell population in this location. They produce histamine and an as yet unidentified peptide hormone. The paracrine action of the ECL cells is to provide histamine to mediate the stimulating effect of gastrin on the acid-secreting parietal cells: the gastrin-ECL cell-parietal cell axis. Secretion of histamine from the ECL cells was studied in intact conscious rats subjected to gastric submucosal microdialysis and using isolated cells in primary culture. The microdialysis experiments revealed that ECL-cell histamine can be mobilized by the local infusion of gastrin, pituitary adenylate cyclase-activating peptide (PACAP), vasoactive intestinal peptide (VIP), peptide YY (PYY), met-enkephalin, endothelin and noradrenaline/adrenaline. While gastrin and met-enkephalin induced a sustained elevation of the submucosal histamine concentration, endothelin, PYY, PACAP, VIP, and noradrenaline/adrenaline induced a transient elevation. Somatostatin, galanin and the prostanoid, misoprostol, inhibited gastrin-stimulated histamine mobilization. Studies of isolated ECL cells (80-90% purity) showed gastrin, PACAP and VIP to stimulate histamine secretion and somatostatin, galanin and misoprostol to inhibit gastrin-stimulated secretion. At present, it seems unlikely that metenkephalin, endothelin, adrenaline and PYY act directly on the ECL cells in situ since the effects could not be reproduced with isolated ECL cells. Clearly, the ECL cells operate under the multifactorial control of circulating hormones, local hormones, catecholamines, neuropeptides and inflammatory mediators.

Gene therapy in transplantation

Gene transfer and gene therapy represent a relatively new field that has grown and expanded enormously in the last 5-10 years. The application of gene transfer and gene medicines to transplantation is currently in its infancy. Consideration for gene medicines in transplantation requires delivery of vectors, either to the graft or to the immune system. Delivery of vectors to the graft provides a choice of potential immunologic targets including: costimulatory signals; inhibitory cytokines; adhesion molecules; and molecules relating to apoptosis. In addition, non-immunologic targets, that increase graft protective mechanisms by reducing ischemic and immunologic damage, represent significant targets for gene transfer. Delivery of vectors to the immune system includes potential targets to modify the immune system, and results in tolerance. Other considerations for gene therapy include the development of additional technologies, such as gene conversion or transgenesis coupled with xenotransplantation, which may provide genetically modified organs. Another important aspect of gene transfer relates to regulation of the transgene expression. A variety of issues concerning innate immunity, adaptive immunity, response to vector components, response to transgene products, and entry of vectors into the antigen presentation and processing pathway require further investigation and refinement of approaches. Lastly, regulatable promoters and the understanding of their interaction with individual cells, tissues and organs, and their interaction with innate and adaptive immunity, are of paramount importance to improving the efficacy and utility of gene transfer. There is no doubt that there is much exciting basic and translational science to be accomplished in the next decade in order to solve these potential barriers and advance gene medicines into the clinical realm in transplantation.

Post-gastrectomy osteopenia in the rat: bone structure is preserved by retaining 10%-30% of the oxyntic gland area

BACKGROUND

The acid-producing part of the rat stomach (fundus) is rich in endocrine cells, i.e. ECL cells and A-like cells. The ECL cells operate under gastrin control and manufacture histamine, the chromogranin-derived peptide pancreastatin and an unidentified peptide hormone. The A-like cells produce ghrelin, a newly discovered growth hormone-releasing hormone. Surgical removal of the entire glandular stomach (gastrectomy, Gx) or the acid-producing part (fundectomy, Fx) causes osteopenia, which is striking in the calvaria. We speculate that the osteopenia develops after surgical removal of the fundus, because the fundus hosts agents that preserve bone. This study examines how much of the fundus is needed to preserve normal skull bone.

METHODS

Increasing portions of the fundus were resected surgically. The serum gastrin, ghrelin and pancreastatin concentrations were measured. The rats were killed after 10 weeks and the calvariae were subjected to transillumination analysis and quantitative histomorphometry.

RESULTS

Fx elevated serum gastrin in proportion to the amount of fundus resected, i.e., the more fundus that was resected, the higher the serum gastrin concentration. Serum ghrelin and pancreastatin concentrations were reduced proportionally to the amount of fundus resected. In rats subjected to 90% or 100% Fx, the calvariae displayed the anticipated pattern of bone loss. No bone loss was seen when 70% or less of the fundus was resected.

CONCLUSIONS

The results of the present study indicate that 10%-30% of the fundic mucosa is needed to preserve bone. The Gx/Fx-evoked osteopenia may be explained by hormonal deficiency caused by surgically eliminating or diminishing one of the endocrine cell populations in the fundic mucosa.

Mucosal T cell response to reovirus

During the last three decades, immunologists and gastroenterologists have witnessed the formation of mucosal immunology as a discipline in biomedical science, and studies of reovirus infection have substantially contributed to this evolution. We have focused on mucosal T cell responses induced by reovirus in conventional, germfree, nude, and NF-kappaB deficient mice. Several major facets of T cell function in the immune responses to this mucosal pathogen have been examined, including viral selection of oligoclonal-T cells, extrathymic T cell development, and distinct signaling pathways used by CD8 sublineages. In addition, our findings with virus-specific T cells selected in the mucosa have suggested novel mechanisms for the rearrangement, selection, and expansion of TCR genes. With the increasing application of molecular tools, reovirus will continue to be a useful model pathogen to study mucosal immunology and will further our understanding of mucosal immunity in health and disease.

Integrated management of the Upper Mersey river basin using the SMILE object-oriented software system

This paper presents the application of the object-oriented framework SMILE to the management of flows and water quality in the Upper Mersey river catchment. The design river flows are those exceeded for 95% of the time, and are estimated applying alternative methods. The influence of compensation reservoirs, surface-water abstractions, and continuous discharges on low river flows is quantified. The annual licensed abstraction volumes are further reviewed. The monitored river water quality is classified using the River Ecosystem scheme. The compliance of the sewage treatment works and trade effluents with their discharge-consent limits is also assessed. The impact of effluents on the variation of river water quality is evaluated through Monte Carlo simulations at the discharge points. The points where the downstream water quality fails to comply with proposed River Quality Objectives are identified. The consent limits of the corresponding discharges are assessed, and changes to the BOD and total ammonia limits are suggested.

[Clinical comparison between intraoperative local arterial infusion chemotherapy and systemic venous chemotherapy of gastric cancer]

OBJECTIVE

To evaluate the effect of intraoperative local arterial infusion chemotherapy for gastric cancer.

METHODS

The effects of intraoperative local arterial infusion chemotherapy in 40 patients with gastric cancer were assessed. Twenty-four patients with gastric cancers who underwent the intraoperative systemic chemotherapy were taken as controls. The removed specimens were examined microscopically to show the degeneration and necrosis of the tumour cell.

RESULTS

After the treatment of the tumour cells, all of the cases in the study group showed various degrees of degeneration and necrosis. The immediate effective rate was 95% for the the study group but only 41.67% for the control group (P < 0.05).

CONCLUSION

Intraoperative local arterial infusion chemotherapy for gastric cancer has good immediate effect and little side effect; it prevents the intraoperative iatrogenic metastases and implantation and decreases the postoperative recurrence of gastric cancer.

Epidermal powder immunization induces both cytotoxic T-lymphocyte and antibody responses to protein antigens of influenza and hepatitis B viruses

Cytotoxic T lymphocytes (CTL) play a vital role in host defense against viral and intracellular bacterial infections. However, nonreplicating vaccines administered by intramuscular injection using a syringe and needle elicit predominantly humoral responses and not CTL responses. Here we report that epidermal powder immunization (EPI), a technology that delivers antigens on 1.5- to 2.5-microm gold particles to the epidermis using a needle-free powder delivery system, elicits CTL responses to nonreplicating antigens. Following EPI, a majority of the antigen-coated gold particles were found in the viable epidermis in the histological sections of the target skin. Further studies using transmission electron microscopy revealed the intracellular localization of the gold particles. Many Langerhans cells (LCs) at the vaccination site contained antigen-coated particles, as revealed by two-color immunofluorescence microscopy, and these cells were found in the draining lymph nodes 20 h later. Immune responses to several viral protein antigens after EPI were studied in mice. EPI with hepatitis B surface antigen (HBsAg) and a synthetic peptide of influenza virus nucleoprotein (NP peptide) elicited antigen-specific CTL responses as well as antibody responses. In an in vitro cell depletion experiment, we demonstrated that the CTL activity against HBsAg elicited by EPI was attributed to CD8(+), not CD4(+), T cells. As controls, needle injections of HBsAg or the NP peptide into deeper tissues elicited solely antibody, not CTL, responses. We further demonstrated that EPI with inactivated A/Aichi/68 (H3N2) or A/Sydney/97 (H3N2) influenza virus elicited complete protection against a mouse-adapted A/Aichi/68 virus. In summary, EPI directly delivers protein antigens to the cytosol of the LCs in the skin and elicits both cellular and antibody responses.