Is intraoperative electrocorticography (ECoG) for long-term epilepsy-associated tumors (LEATs) more useful in children?-A Randomized Controlled Trial.

OBJECTIVES: The utility of intraoperative electrocorticography (ECoG)-guided resective surgery for pediatric long-term epilepsy-associated tumors (LEATs) with antiseizure medication (ASM) resistant epilepsy is not supported by robust evidence. As epilepsy networks and their ramifications are different in children from those in adults, the impact of intraoperative ECoG-based tailored resections in predicting prognosis and influencing outcomes may also differ. We evaluated this hypothesis by comparing the outcomes of resections with and without the use of ECoG in children and adults by a randomized study. METHODS: From June 2020 to January 2022, 42 patients (17 children and 25 adults) with LEATs and antiseizure medication (ASM)-resistant epilepsy were randomly assigned to one of the 2 groups (ECoG or no ECoG), prior to surgical resection. The 'no ECoG' arm underwent gross total lesion resection (GTR) without ECoG guidance and the ECoG arm underwent GTR with ECoG guidance and further additional tailored resections, as necessary. Factors evaluated were tumor location, size, lateralization, seizure duration, preoperative antiepileptic drug therapy, pre- and postresection ECoG patterns and tumor histology. Postoperative Engel score and adverse event rates were compared in the pediatric and adult groups of both arms. Eloquent cortex lesions and re-explorations were excluded to avoid confounders. RESULTS: Forty-two patients were included in the study of which 17 patients were in the pediatric cohort (age < 18 years) and 25 in the adult cohort. The mean age in the pediatric group was 11.11 years (SD 4.72) and in the adult group was 29.56 years (SD 9.29). The mean duration of epilepsy was 9.7 years (SD 4.8) in the pediatric group and 10.96 (SD 8.8) in the adult group. The ECoG arm of LEAT resections had 23 patients (9 children and 14 adults) and the non-ECoG arm had 19 patients (8 children and 11 adults). Three children and 3 adults from the ECoG group further underwent ECoG-guided tailored resections (average 1.33 additional tailored resections/per patient.).The histology of the tailored resection specimen was unremarkable in 3/6 (50%).Overall, the commonest histology in both groups was ganglioglioma and the temporal lobe, the commonest site of the lesion. 88.23% of pediatric cases (n = 15/17) had an excellent outcome (Engel Ia) following resection, compared to 84% of adult cases (n = 21/25) at a mean duration of follow-up of 25.76 months in children and 26.72 months in adults (p = 0.405).There was no significant difference in seizure outcomes between the ECoG and no ECoG groups both in children and adults, respectively (p > 0.05). Additional tailored resection did not offer any seizure outcome benefit when compared to the non-tailored resections. CONCLUSIONS: The use of intraoperative electrocorticography in LEATs did not contribute to postoperative seizure outcome benefit in children and adults. No additional advantage or utility was offered by ECoG in children when compared to its use in adults. ECoG-guided additional tailored resections did not offer any additional seizure outcome benefit both in children and adults.

The Concise Guide to PHARMACOLOGY 2023/24: Ion channels.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16178. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

Evaluation of the efficacy of tongue swab and saliva as samples for testing COVID-19 infection in symptomatic cases in comparison with nasopharyngeal swab.

Introduction. COVID-19 caused by SARS CoV-2 continues to be a major health concern globally. Methods for detection of the disease are necessary for public health efforts to monitor the spread of this disease as well as for detecting the emergence of new variants.Gap statement. Collection of Nasopharyngeal swab (NPS), the gold standard sample for the detection of COVID-19 infection by RT-qPCR is invasive and requires the expertise of a trained medical provider. This highlights the need for validating less invasive samples that can be self-collected without the need for trained medical provider.Aim. To validate saliva and tongue swab as potential samples for the diagnosis of COVID-19.Methodology. Adult and paediatric cases who had acute influenza like illness were enrolled in the study. The study involved comparison of Nucleic Acid Amplification Tests (NAAT) results for the detection of COVID-19 obtained by using saliva and tongue swab with that of NPS.Result and Conclusion. The sensitivity and specificity of saliva as sample for COVID-19 detection were found to be 71 and 88% respectively whereas those of tongue swab as sample were 78 and 90 %. Further validation was based on the positive and negative predictive values, the likelihood ratio, agreement percentage and the kappa statistic. The findings of the study point towards tongue swab and saliva as suitable alternative samples for the diagnosis of COVID-19 with a slightly higher accuracy and agreement for tongue swab than saliva. However considering the fatality of COVID-19, they are better suited for mass screening of people than for diagnosis.

Eleven Crucial Pesticides Appear to Regulate Key Genes That Link MPTP Mechanism to Cause Parkinson's Disease through the Selective Degeneration of Dopamine Neurons.

Pesticides kill neurons, but the mechanism leading to selective dopaminergic loss in Parkinson's disease (PD) is unknown. Understanding the pesticide's effect on dopaminergic neurons (DA) can help to screen and treat PD. The critical uptake of pesticides by the membrane receptors at DA is hypothesized to activate a signaling cascade and accelerate degeneration. Using MPTP as a reference, we demonstrate the mechanisms of eleven crucial pesticides through molecular docking, protein networks, regulatory pathways, and prioritization of key pesticide-regulating proteins. Participants were recruited and grouped into control and PD based on clinical characteristics as well as pesticide traces in their blood plasma. Then, qPCR was used to measure pesticide-associated gene expression in peripheral blood mononuclear cells between groups. As a result of molecular docking, all eleven pesticides and the MPTP showed high binding efficiency against 274 membrane receptor proteins of DA. Further, the protein interaction networks showed activation of multiple signaling cascades through these receptors. Subsequent analysis revealed 31 biological pathways shared by all 11pesticides and MPTP that were overrepresented by 46 crucial proteins. Among these, CTNNB1, NDUFS6, and CAV1 were prioritized to show a significant change in gene expression in pesticide-exposed PD which guides toward therapy.

A study on seroconversion following first & second doses of ChAdOx1 nCoV-19 vaccine in Central Kerala.

Background & objectives: Vaccination against COVID-19 induces spike protein-binding IgG antibodies, a robust correlate of protection against COVID-19. This study was undertaken to assess the humoral response after completion of both the doses of ChAdOx1 nCoV vaccine in healthcare workers (HCWs) at a tertiary care health centre in India. Methods: A cross-sectional COVID-19 vaccine-induced antibody study was conducted among HCWs. IgG antibodies against spike protein were measured at least 28 days after the first dose and the second dose of vaccination in both SARS CoV-2 naïve and recovered HCWs. Mean and median antibody titre following each dose of vaccine and its association with age, gender, co-morbidities and factors such as exercise, stress and sleep deprivation were also explored. Results: Among the 200 vaccine recipients, 91.5 per cent showed seroconversion after the first dose and 99.5 per cent after the second dose. The mean titre after the second dose was significantly higher when compared to the first dose (12.68±4.17 vs. 9.83±6.3, P=0.001). More than half (54%) had high antibody titre ≥12 S/Co (Signal/cut-off). Previous COVID-19 infection was the single most important factor influencing antibody production, where the mean titre just after a single dose [mean-17.81±5.94, median-20.5 (interquartile range [IQR]-3.7)] surpassed the titre after the second dose in SARS CoV-2 naïve individuals [mean-12.29±4.00, median-12.8 (IQR-3.7), P=0.001]. Furthermore, 28 per cent of vaccinees showed a reduction in titre after the second dose. The mean fall in titre was 2.25±1.40 and was more pronounced in males, the younger age group and those with previous COVID-19 infection. Interpretation & conclusions: ChAdOx1 nCov-19 vaccine after two doses elicited an excellent immune response. However, greater immunogenicity after the first dose was seen among those with previous COVID-19 infection, even surpassing the titre achieved by the second dose of vaccine in SARS CoV-2 naïve recipients. A fall in antibody titre after the second dose is a matter of concern and requires further studies.

THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: Ion channels.

The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15539. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.

Gastrointestinal parasites of Asian elephants (Elephas maximus L. 1798) in south Wayanad forest division, Kerala, India.

Microscopic-coprological examination of Asian Elephant (Elephas maximus L., 1798) dung piles (n = 55) in South Wayanad Forest Division from March to August, 2017 revealed 74.5% prevalence of parasites in elephants. Ancylostoma sp. Anoplocephala sp., Strongyle type egg and Strongyloides sp. were the major parasites recorded. Strongyloides sp. and Strongyle type egg were observed more frequently (58.1%). Ancylostoma sp. and Anoplocephala sp. were constituted 1.8% each; mixed parasitic species infections were recorded. The frequency distribution of parasitic load in elephants showed skewed distribution of propagules. Centrifugal sedimentation and floatation methods of fecal examination of outer and inner regions of dung did not show significant difference in number of propagules. The highest number of parasitic propagules was recorded in floatation method. The number of propagules varied among dung samples of different herds collected from different localities. There were no relation between the parasitic load and age of elephants. The mean density of parasite eggs was higher in solitary animals (214.3 ± 155.4 epg) than herd elephants (147.78 ± 111.1 epg). Though parasitic load was higher in solitary males, based on the occurrence of parasites using logistic regression it was found that females had 1.83 times higher occurrence for parasitic infection than males. Both length and width of parasite egg size classes were used to classify into different taxonomic groups using discriminate function analysis. Three distinct size clusters were identified. Nematode and Cestode eggs were classified correctly with 95.7% accuracy. Since, the egg size was similar in nematode group separation into genus was difficult. Further, inclusion of stages of development of egg and larvae enable better separation.

Domain structure and function of matrix metalloprotease 23 (MMP23): role in potassium channel trafficking.

MMP23 is a member of the matrix metalloprotease family of zinc- and calcium-dependent endopeptidases, which are involved in a wide variety of cellular functions. Its catalytic domain displays a high degree of structural homology with those of other metalloproteases, but its atypical domain architecture suggests that it may possess unique functional properties. The N-terminal MMP23 pro-domain contains a type-II transmembrane domain that anchors the protein to the plasma membrane and lacks the cysteine-switch motif that is required to maintain other MMPs in a latent state during passage to the cell surface. Instead of the C-terminal hemopexin domain common to other MMPs, MMP23 contains a small toxin-like domain (TxD) and an immunoglobulin-like cell adhesion molecule (IgCAM) domain. The MMP23 pro-domain can trap Kv1.3 but not closely-related Kv1.2 channels in the endoplasmic reticulum, preventing their passage to the cell surface, while the TxD can bind to the channel pore and block the passage of potassium ions. The MMP23 C-terminal IgCAM domain displays some similarity to Ig-like C2-type domains found in IgCAMs of the immunoglobulin superfamily, which are known to mediate protein-protein and protein-lipid interactions. MMP23 and Kv1.3 are co-expressed in a variety of tissues and together are implicated in diseases including cancer and inflammatory disorders. Further studies are required to elucidate the mechanism of action of this unique member of the MMP family.

Raised intrathecal levels of APRIL and BAFF in patients with systemic lupus erythematosus: relationship to neuropsychiatric symptoms.

INTRODUCTION: The tumour necrosis factor (TNF) family ligands BAFF (B-cell activating factor of TNF family) and APRIL (a proliferation-inducing ligand) are essential for B-cell survival and function. Elevated serum levels of BAFF and APRIL have been reported earlier in patients with systemic lupus erythematosus (SLE). Since autoantibody formation in the central nervous system (CNS) is a distinct feature of neuropsychiatric SLE (NPSLE), we have investigated whether NPSLE is associated with an enhanced intrathecal production of APRIL and BAFF. METHODS: Levels of BAFF and APRIL in cerebrospinal fluid (CSF) and serum from healthy controls, SLE patients without CNS involvement, and patients with NPSLE were determined by enzyme-linked immunosorbent assay. Interleukin-6 (IL-6) levels were determined by an IL-6-specific bioassay. RESULTS: SLE patients had levels of APRIL in CSF that were more than 20-fold higher and levels of BAFF in CSF that were more than 200-fold higher than those of healthy controls. Separate analyses of SLE patients with and without CNS involvement revealed that NPSLE patients had enhanced levels of APRIL in CSF. BAFF and APRIL were likely produced locally in the CNS as CSF and serum levels did not correlate. Moreover, CSF levels of APRIL correlated with BAFF but not with IL-6, suggesting that APRIL and BAFF in the CNS are regulated together but that they are produced independently of IL-6. CONCLUSION: To our knowledge this is the first study to show elevated levels of BAFF and APRIL in CSF of SLE patients. APRIL was augmented in NPSLE patients compared with SLE patients without CNS involvement. APRIL and BAFF antagonists breeching the blood-brain barrier therefore could have beneficial effects on SLE patients, in particular patients with NPSLE.

Th17 development and autoimmune arthritis in the absence of reactive oxygen species.

Dendritic cells (DC) express a functional NADPH oxidase and produce reactive oxygen species (ROS) upon interaction with microbes and T cells. Exposure to ROS leads to DC activation and maturation, as evidenced by phenotypic and functional changes. We have evaluated how endogenous ROS production affects the cytokine secretion pattern and T cell-activating capacity of bone marrow-derived murine DC. DC treated with ROS scavengers, as well as DC from mice that lack a functional NADPH oxidase (and thereby inherently deficient in ROS production) produced significantly increased levels of IL-1beta, IL-6, TNF-alpha and TGF-beta in response to microbial activation. DC deficient in ROS production induced high levels of IFN-gamma and IL-17 in responding T cells after Ag-specific or superantigen-induced activation. Finally, we show that ROS deficiency affected the induction of a T cell-dependent inflammatory condition, collagen-induced arthritis (CIA). C57BL/6 mice that lack a functional NADPH oxidase developed a severe and erosive CD4-dependent CIA, whereas the majority of the congenic wild-type animals remained healthy. These data suggest that ROS act as immunomodulators in DC-driven T cell activation and perhaps also in T cell-dependent immunopathology.

Oral tolerance induction by mucosal administration of cholera toxin B-coupled antigen involves T-cell proliferation in vivo and is not affected by depletion of CD25+ T cells.

Oral administration of antigens coupled to the B subunit of the cholera toxin (CTB) can dramatically reduce the amount of antigen needed for tolerance induction and has been used in several animal models to suppress conditions where the immune system overreacts to foreign and self-antigens. In this study, the cellular events following oral administration of CTB-coupled antigen was investigated. As a model system, limited numbers of CSFE-labelled cells from influenza haemagglutinin peptide (HApep) T-cell transgenic mice were transferred to wild type mice and the mice were then given CTB-coupled HApep orally. The inductive events of CTB-induced tolerance was characterized by extensive proliferation of HApep-specific T cells in the mesenteric lymph nodes (MLNs) and in the spleen. The proliferating cells up-regulated the gut homing molecule alpha4beta7 and down-regulated the high endothelial venule binding molecule L-selectin. Addition of the whole cholera toxin (CT) to CTB-HApep showed a similar pattern as CTB-HApep feeding, with antigen-specific proliferation in the MLN and spleen and expression of alpha4beta7 on the proliferating cells. However, addition of CT to CTB-HApep, produced a stronger and faster proliferative response and abrogated CTB-HA mediated oral tolerance. Feeding of CTB-HApep expanded CD25+ cells in the MLNs. CTB-induced oral tolerance could, however, not be explained by CD25+ dependent regulatory activity, as oral administration of CTB-HApep to mice depleted of CD25+ cells still gave rise to systemic tolerance. Thus, several mechanisms might co-orchestrate the systemic tolerance seen in response to feeding with CTB-coupled antigen.

Mucosal adjuvants and anti-infection and anti-immunopathology vaccines based on cholera toxin, cholera toxin B subunit and CpG DNA.

Mucosal immunisation may be used both to protect the mucosal surfaces against infections and as a means for immunological treatment of peripheral immunopathological disorders through the induction of systemic antigen-specific tolerance ('oral tolerance'). The development of mucosal vaccines, whether for prevention of infectious diseases or for oral tolerance immunotherapy, requires efficient antigen delivery and adjuvant systems that can help to present the appropriate vaccine or immunotherapy antigens to the mucosal immune system. The most potent (but also toxic) mucosal adjuvants are cholera toxin (CT) and the closely related Escherichia coli heat-labile enterotoxin (LT), and much effort and significant progress have been made recently to generate toxicologically acceptable derivatives of these toxins with retained adjuvant activity. Among these are the non-toxic, recombinantly produced cholera toxin B-subunit (CTB). CTB is a specific protective antigen component of a widely registered oral cholera vaccine as well as a promising vector for either giving rise to mucosal anti-infective immunity or for inducing peripheral anti-inflammatory tolerance to chemically or genetically linked foreign antigens administered mucosally. CT and CTB have also recently been used as combined vectors and adjuvants for markedly promoting ex vivo dendritic cell (DC) vaccination with different antigens and also steering the immune response to the in vivo-reinfused DCs towards either broad Th1 + Th2 + CTL immunity (CT) or Th2 or tolerance (CTB). Another type of mucosal adjuvants is represented by bacterial DNA or synthetic oligodeoxynucleotides containing CpG-motifs, which especially when linked to CTB have been found to effectively stimulate both innate and adaptive mucosal immune responses. The properties and clinical potential of these different classes of adjuvants are being discussed.

Transcutaneous immunization with cholera toxin B subunit adjuvant suppresses IgE antibody responses via selective induction of Th1 immune responses.

Topical application of cholera toxin (CT) onto mouse skin can induce a humoral immune response to CT as well as to coadministered Ags. In this study, we examined the nontoxic cell-binding B subunit of CT (CTB) as a potential adjuvant for cutaneous immune responses when coadministered with the prototype protein Ag, OVA. CTB applied onto skin induced serum Ab responses to itself with magnitudes comparable to those evoked by CT but was poorly efficient at promoting systemic Ab responses to coadministered OVA. However, transcutaneous immunization (TCI) with either CT or CTB and OVA led to vigorous OVA-specific T cell proliferative responses. Furthermore, CTB potentiated Th1-driven responses (IFN-gamma production) whereas CT induced both Th1 and Th2 cytokine production. Coadministration of the toxic subunit CTA, together with CTB and OVA Ag, led to enhanced Th1 and Th2 responses. Moreover, whereas TCI with CT enhanced serum IgE responses to coadministered OVA, CTB suppressed these responses. TCI with either CT or CTB led to an increased accumulation of dendritic cells in the exposed epidermis and the underlying dermis. Thus, in contrast to CT, CTB appears to behave very differently when given by the transcutaneous as opposed to a mucosal route and the results suggest that the adjuvanticity of CT on Th1- and Th2-dependent responses induced by TCI involves two distinct moieties, the B and the A subunits, respectively.

Cholera toxin B subunit as a carrier molecule promotes antigen presentation and increases CD40 and CD86 expression on antigen-presenting cells.

Cholera toxin B subunit (CTB) is an efficient mucosal carrier molecule for the generation of mucosal antibody responses and/or induction of systemic T-cell tolerance to linked antigens. CTB binds with high affinity to GM1 ganglioside cell surface receptors. In this study, we evaluated how conjugation of a peptide or protein antigen to CTB by chemical coupling or genetic fusion influences the T-cell-activating capacity of different antigen-presenting cell (APC) subsets. Using an in vitro system in which antigen-pulsed APCs were incubated with antigen-specific, T-cell receptor-transgenic T cells, we found that the dose of antigen required for T-cell activation could be decreased >10,000-fold using CTB-conjugated compared to free antigen. In contrast, no beneficial effects were observed when CTB was simply admixed with antigen. CTB conjugation enhanced the antigen-presenting capacity not only of dendritic cells and B cells but also of macrophages, which expressed low levels of cell surface major histocompatibility complex (MHC) class II and were normally poor activators of naive T cells. Enhanced antigen-presenting activity by CTB-linked antigen resulted in both increased T-cell proliferation and increased interleukin-12 and gamma interferon secretion and was associated with up-regulation of CD40 and CD86 on the APC surface. These results imply that conjugation to CTB dramatically lowers the threshold concentration of antigen required for immune cell activation and also permits low-MHC II-expressing APCs to prime for a specific immune response.

Vaccination with Bordetella pertussis-pulsed autologous or heterologous dendritic cells induces a mucosal antibody response in vivo and protects against infection.

This study demonstrates for the first time that vaccination with either autologous or heterologous dendritic cells (DC) pulsed with specific antigen induces protective immune responses against noninvasive bacteria, namely Bordetella pertussis. The DC-mediated protection is associated with strong B. pertussis-specific immunoglobulin G (IgG) and IgA responses in the lung.

Mucosal immunity and tolerance: relevance to vaccine development.

The mucosal immune system of mammals consists of an integrated network of lymphoid cells which work in concert with innate host factors to promote host defense. Major mucosal effector immune mechanisms include secretory antibodies, largely of immunoglobulin A (IgA) isotype, cytotoxic T cells, as well as cytokines, chemokines and their receptors. Immunologic unresponsiveness (tolerance) is a key feature of the mucosal immune system, and deliberate vaccination or natural immunization by a mucosal route can effectively induce immune suppression. The diverse compartments located in the aerodigestive and genitourinary tracts and exocrine glands communicate via preferential homing of lymphocytes and antigen-presenting cells. Mucosal administration of antigens may result in the concomitant expression of secretory immunoglobulin A (S-IgA) antibody responses in various mucosal tissues and secretions, and under certain conditions, in the suppression of immune responses. Thus, developing formulations based on efficient delivery of selected antigens/tolerogens, cytokines and adjuvants may impact on the design of future vaccines and of specific immunotherapeutic approaches against diseases associated with untoward immune responses, such as autoimmune disorders, allergic reactions, and tissue-damaging inflammatory reactions triggered by persistent microorganisms.

Antigen presentation in the murine oral epithelium.

We have previously reported that the buccal mucosa can support delayed type hypersensitivity (DTH) reactions to contact sensitizers. In the present study, we show that cells isolated from the buccal epithelium are able to present soluble exogenous antigens to specific T cells. Single cell suspensions obtained by enzymatic dispersion of buccal epithelial sheets could present the native protein antigen hen-egg lysozyme (HEL) to the I-Ak-restricted CD4+ T-cell hybridoma specific for a.a 46-61 on HEL. T-cell activation resulted in interleukin-2 (IL-2) production which could be inhibited by anti-major histocompatibility complex (MHC) class-II antibodies of pertinent specificity. Immunohistochemical staining of whole buccal epithelial sheets revealed that all MHC II positive cells had a dendritic morphology and expressed ATPase activity, indicating that these cells represent a major antigen-presenting cell (APC) population in this tissue. Furthermore, single cell suspensions isolated from buccal epithelium (BEC) after local in vivo administration of either a native soluble protein, a synthetic dodecapeptide, or a contact sensitizer were able to activate antigen-specific T cells ex vivo. Kinetic analyses indicated that maximal APC activity in the oral epithelium occurred within 1 hr after local antigen administration, and had essentially vanished after 24 hr. Conversely, APC activity was undetectable in draining cervico-mandibular lymph node cell suspensions recovered 1 hr after local antigen injection but became manifest after 3-24 hr. These observations suggest that dendritic cells can acquire antigens in the buccal epithelium and migrate to draining lymph nodes where they present processed antigen to MHC class II-restricted T cells. This APC population may thus be a critical element in the initiation of Th1-driven DTH responses in the oral mucosa.

Differential in vivo effects of a superantigen and an antibody targeted to the same T cell receptor. Activation-induced cell death vs passive macrophage-dependent deletion.

Superantigens have multiple pleiotropic effects in vivo, causing the activation, proliferation, and deletion of specific T cells. In our study, we analyzed the effects of the bacterial superantigen Staphylococcus aureus enterotoxin B (SEB) on peripheral T cells in vivo. As an internal control we took advantage of a IgG2a mAb, F23.1 (anti-V beta 8), that recognizes products from the same V beta gene family as that recognized by SEB. Suprisingly, not only SEB, but also F23.1 primes peripheral T cells to undergo oligonucleosomal DNA fragmentation typical for programmed cell death (PCD). Nonetheless the deletion and induction of PCD imposed by both agents obey rather different principles. First, SEB, not F23.1-induced PCD, concerns T cells that have passed through the S phase of the cell cycle, as demonstrated by experiments in which the thymidine analogue 5-bromo-2'desoxyuridine was detected in mono- and oligonucleosomal fragments of T cells undergoing PCD. Second, deletion of V beta 8+ T cells induced by SEB, not F23.1, can be blocked in vivo by high doses of retinol and, during the early phase, by glucocorticoid receptor blockade with RU-38486. Inasmuch as retinol fails to antagonize the glucocorticoid-induced PCD, at least two pathways are involved in early SEB-driven deletion, one that depends on the presence of endogenous glucocorticoid, and another that can be inhibited by retinol. Third, depletion of phagocytes in vivo by means of liposome-encapsulated dichloromethylene diphosphonate does not impede the activation and deletion of V beta 8+ cells by SEB, although it partially prevents the elimination of T cells binding F23.1 in vivo. Thus, macrophages are not rate-limiting for the action of SEB. In a further series of experiments, we demonstrate that SEB causes the secretion of a variety of cytokines (IL-1, -2, -4, -10, granulocyte-macrophage-CSF, IFN-gamma, and TNF) that may cause lethal septic shock. In contrast, F23.1 that efficiently induces all these mediators in vitro, fails to do so in vivo. In synthesis, the elimination of T cells induced by two different agents specific for V beta 8 obeys different principles: activation-induced cell death in the case of SEB and passive macrophage-mediated elimination in the case of F23.1.