Amino acids at position 5 in the peptide/MHC binding region of a public virus-specific TCR are completely inter-changeable without loss of function.

Anti-viral T-cell responses are usually directed against a limited set of antigens, but often contain many T cells expressing different T-cell receptors (TCRs). Identical TCRs found within virus-specific T-cell populations in different individuals are known as public TCRs, but also TCRs highly-similar to these public TCRs, with only minor variations in amino acids on specific positions in the Complementary Determining Regions (CDRs), are frequently found. However, the degree of freedom at these positions was not clear. In this study, we used the HLA-A*02:01-restricted EBV-LMP2FLY -specific public TCR as model and modified the highly-variable position 5 of the CDR3ß sequence with all 20 amino acids. Our results demonstrate that amino acids at this particular position in the CDR3ß region of this TCR are completely inter-changeable, without loss of TCR function. We show that the inability to find certain variants in individuals is explained by their lower recombination probability rather than by steric hindrance.

Update about Oralair® as a treatment for grass pollen allergic rhinitis.

Sublingual immunotherapy (SLIT) is a well-tolerated, safe, and effective approach to treating allergic rhinitis (AR). Oralair® is a five-grass pollen SLIT tablet containing natural pollen allergens from five of the major grass species responsible for seasonal AR due to grass pollen allergy. Recommended use is in a pre-coseasonal regimen, starting daily treatment approximately 4 months before the start of the pollen season, with treatment then continued daily throughout the season; treatment should continue for 3-5 y. Clinical efficacy and safety of Oralair® in patients with grass pollen-induced AR has been demonstrated in a comprehensive clinical development program of randomized controlled trials. Effectiveness has been substantiated in subsequent observational studies with sustained efficacy following treatment cessation and a favorable level of adherence, quality of life, benefit, and satisfaction for the patients. Supportive evidence for a benefit in reducing the risk or delaying the development of allergic asthma is emerging.

Prevalence of primary aldosteronism in hypertensive kidney transplant recipients: A cross-sectional study.

Due to high prevalence of primary aldosteronism (PA) in the general hypertensive population, and its association with worse cardiovascular and renal outcomes, the 2016 Endocrine Society Guidelines explicitly recognize PA as a major public health issue requiring urgent attention. Its prevalence in hypertensive kidney transplant recipients (KTRs) is unknown. In this cross-sectional study, we screened KTRs with hypertension who were on ≥4 antihypertensive medications, on 3 antihypertensive medications with BP ≥ 140/90, and on potassium supplements, or were hypokalemic. 172 of 280 eligible patients successfully completed the testing. A positive screen for PA defined by an aldosterone-to-renin ratio of ≥20 and a plasma aldosterone concentration of >15 ng/dL yielded a prevalence of 15.7%. Potassium supplement requirement (52% vs 27%, P = .01) and hypokalemia (25.9% vs 4.8%, P < .01) were more common in patients who screened positive compared with those who screened negative. 67% of patients who screened positive were on potassium supplements and/or were hypokalemic. Our study is the first to systematically explore the prevalence of PA among the hypertensive KTR population, which has inherently high cardiovascular risk. Further studies are needed to determine the cardiovascular and renal risk attributable to PA, and define optimal therapy for KTRs with PA.

Predictive role of gnathological techniques for the treatment of persistent idiopathic facial pain (PIFP).

INTRODUCTION/BACKGROUND: Persistent idiopathic craniofacial pain (PIFP) is a heterogeneous group of pain syndromes whose main characteristic is the daily presence of persistent pain for at least 3 months. The pathophysiology of PIFP is still not entirely known and probably related to biological and psychological factors. Although PIFP has been attributed to the central neuron activity, the importance of masticatory muscles as a possible pathogenic mechanism was recently demonstrated. The main purpose of our paper was to identify the physiological rest position of the mandible with minimal tonus of both the elevator and depressor muscles and the neuromuscular trajectory of mouth closing obtained by transcutaneous electrical stimulation (TENS) and maintained with the use of an occlusal device, known as orthotic. MATERIALS AND METHODS: The VAS scale for facial pain and the migraine disability assessment score (MIDAS) index for patient quality of life were evaluated at the beginning of the study for the 38 subjects that came to our attention. Our research included two phases. The first phase consisted of kinesiographic and electromyographic (EMG) examinations of the masticatory muscles and a 45-min application of TENS in order to deprogram the muscular activity. Kinesio-electromyographic examinations were repeated in the second phase. The main evaluated parameter was jaw deflection or deviation on the sagittal and frontal planes before and after TENS during patient tooth occlusion. Patients that showed a significant modification of this parameter were treated with orthotics for 12 months. RESULTS: The results of a 12-month follow-up show a sharp reduction of the VAS (pre-orthotic 9.05, range 8-10, SD 0.8; post-orthotic 5.87, range 1-5, SD 0.7) and an improvement in the quality of life (MIDAS). CONCLUSIONS: Our study demonstrated the usefulness of TENS as a screening method for the application of orthotics. This non-invasive and/or non-painful procedure could be a useful complementary treatment in this patient population. The results of the study also confirm the role of masticatory muscle dynamics as a possible pathogenic mechanism in patients with PIFP.

The role of electrophysiological investigations of masticatory muscles in patients with persistent idiopathic facial pain.

INTRODUCTION: The authors tried to establish whether there is any electrophysiological difference of masticatory muscle activity between patients with persistent idiopathic facial pain (PIFP) and healthy subjects. METHODS: Twenty-eight PIFP patients (6 men and 22 women, mean age 40 years) and 28 normal subjects (12 men and 16 women, mean age 40 years) underwent EMG of temporal and masseter muscles before and after transcutaneous electric nerve stimulation (TENS). RESULTS: After TENS stimulation, the mean amplitude difference was found to be smaller than the baseline before TENS in the PIFP patients compared with healthy subjects. CONCLUSIONS: The peculiar behavior of masticatory muscles after TENS could be relevant in order to explain the well-known improvement of pain reported by some PIFP patients after orthosis positioning.

The Association of 25-Hydroxyvitamin D Levels with Late Cytomegalovirus Infection in Kidney Transplant Recipients: the Wisconsin Allograft Recipient Database.

BACKGROUND: Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in kidney transplant recipients. Vitamin D has an integral role in proper immune function, and deficiency is common among kidney transplant recipients. It remains unclear whether 25-hydroxyvitamin D [25(OH)D] level is associated with CMV infection in kidney transplant recipients. METHODS: We examined the relationship between 25(OH)D levels, measured at least 6 months posttransplant, and subsequent CMV infection in 1976 recipients free of prior CMV infection. RESULTS: Of 1976 recipients, 251 (12.7%) were vitamin D deficient [25(OH)D <20 ng/mL] and 548 (27.7%) were insufficient (20-29 ng/mL) at the time of the first 25(OH)D measurement. A total of 107 recipients had a CMV infection within 1 year of a 25(OH)D measurement. Vitamin D deficiency was associated with a 1.81-fold higher risk (relative hazard = 1.81; 95% confidence interval [CI], 1.06-3.09) than vitamin D sufficiency after adjustment for baseline characteristics and concurrent graft function and blood calcineurin inhibitor concentration. Each 1 ng/mL lower 25(OH)D was associated with a 2% higher risk of infection (95% CI, 0%-4%) in continuous analyses after adjustment. CONCLUSIONS: Low 25(OH)D is common in kidney transplant recipients and associated with late CMV infection. These results highlight the need for interventional trials to assess the potential for vitamin D supplementation to reduce infectious complications in kidney transplant recipients.

[Characteristics of non-pharmacological interventions in the elderly with COPD. Smoking cessation, pulmonary rehabilitation, nutritional management and patient education]. / Particularités de la prise en charge non médicamenteuse de la BPCO chez les sujets âgés. Réhabilitation, sevrage tabagique, nutrition et éducation thérapeutique.

Chronic obstructive pulmonary disease (COPD) is a respiratory disorder responsible for a high mortality and disability. People older than 65 years are more commonly affected than younger people and tend to present with more symptoms and a greater level of disability. Non-pharmacological interventions play an important role in the management of all patients with COPD and this is particularly true in the elderly. Given the improvement in quality of life and risk of hospitalization, smoking cessation should be promoted to patients of all ages. Increased physical activity is associated with reduced respiratory symptoms. Tests such as the "Short Physical Performance Battery" can be useful in frailer older people with COPD, while walking tests such as the 6-minute walk test are used as an assessment before pulmonary rehabilitation. Increased physical activity should be combined with nutritional management. Screening for undernutrition by questionnaire, body mass index and albumin quantification is recommended in the elderly. In case of undernutrition, oral supplementation seems to reduce the risk of re-admission. All these measures must be included in an education program adapted to the elderly comorbidities (hearing loss, isolation…).

[Allergen-specific immunotherapy in the treatment of pollen allergy]. / Immunothérapie allergénique dans le traitement de l'allergie aux pollens.

Since its description by Noon in 1911, desensitization or allergen-specific immunotherapy (SIT) has been largely given by sub cutaneous injection in the treatment of allergic diseases. It remains the only treatment for allergic diseases aimed at the etiology. The development of sublingual route as an alternative to sub cutaneous injection, and of new forms of medication, has led to large-scale clinical trials, many of them performed with allergen tablets, particularly in the field of pollen allergy. These studies have confirmed that SIT is efficient in reducing allergic respiratory symptoms. Data on long term benefits and sustained efficacy after stopping treatment have also been published. These show an impact on the natural history of allergic disease and, in particular, a reduction in the risk of asthma in desensitized rhinitic subjects and in the acquisition of new sensitivities. The basic mechanisms of immunotherapy are becoming better understood and allow us to envisage improvements in this technique in the future. The sublingual route improves the risk/benefit ratio of desensitization and reduces the risk of serious side effects. These data suggest that the indications for SIT may be extended in a large number of patients with allergic respiratory diseases.

p-Sulfonato-calix[n]arenes inhibit staphylococcal bicomponent leukotoxins by supramolecular interactions.

PVL (Panton-Valentine leukocidin) and other Staphylococcus aureus ß-stranded pore-forming toxins are important virulence factors involved in various pathologies that are often necrotizing. The present study characterized leukotoxin inhibition by selected SCns (p-sulfonato-calix[n]arenes): SC4, SC6 and SC8. These chemicals have no toxic effects on human erythrocytes or neutrophils, and some are able to inhibit both the activity of and the cell lysis by leukotoxins in a dose-dependent manner. Depending on the type of leukotoxins and SCns, flow cytometry revealed IC50 values of 6-22 µM for Ca2+ activation and of 2-50 µM for cell lysis. SCns were observed to affect membrane binding of class S proteins responsible for cell specificity. Electrospray MS and surface plasmon resonance established supramolecular interactions (1:1 stoichiometry) between SCns and class S proteins in solution, but not class F proteins. The membrane-binding affinity of S proteins was Kd=0.07-6.2 nM. The binding ability was completely abolished by SCns at different concentrations according to the number of benzenes (30-300 µM; SC8>SC6≫SC4). The inhibitory properties of SCns were also observed in vivo in a rabbit model of PVL-induced endophthalmitis. These calixarenes may represent new therapeutic avenues aimed at minimizing inflammatory reactions and necrosis due to certain virulence factors.

The burden associated with ocular symptoms in allergic rhinitis.

BACKGROUND: Ocular symptoms remain widely neglected while they concern the majority of subjects with allergic rhinitis (AR) and impair their daily activities. We describe the characteristics of ocular symptoms in subjects suffering from AR in the French INSTANT study and their impact on daily activities. METHODS: This cross-sectional observational survey was carried out in November 2006 using face-to-face interviews. RESULTS: 31.7% of the population-based sample (n = 4,019) suffered from AR and 52.0% of AR subjects (n = 663) described ocular symptoms. Men had significantly less ocular symptoms than women (odds ratio 0.71, 95% CI 0.57-0.89). 57.5% of subjects suffered from ocular symptoms for >5 years, 30.2% for >6 months in the past 12 months, and 92.2% during the pollen season. The troublesome ocular symptoms were itching eyes (51.1%), watery eyes (38.6%), red eyes (6.6%) and swollen eyelids (3.6%). The trigger factors were pollens (51.3%), household dust and mites (34.8%), pets (12.2%) and air pollution (3.8%). Ocular symptoms had a negative impact on daily activities (blurred sight 47.8%, reduction in daily activities 38.8%, reduction in efficacy at work 25.8%, sleep disturbances 16.3%, and sick leave 12.9%). They were diagnosed in 38.9% of subjects and followed up in 34.8%. Treatment for ocular symptoms was prescribed to 35.4% of subjects and to 61.9% of subjects with a regular follow-up care. CONCLUSIONS: This survey confirms the impact of ocular symptoms on AR patients' lives and suggests that they are still neglected and undertreated.

The average Adjusted Symptom Score, a new primary efficacy end-point for specific allergen immunotherapy trials.

BACKGROUND: In clinical trials, the efficacy of immunotherapy for allergic rhinoconjunctivitis symptoms is often evaluated with the average Rhinoconjunctivitis Total Symptom Score (ARTSS). Effective treatment is associated with a lower ARTSS vs. placebo but use of rescue medication to alleviate symptoms reduces the RTSS and decreases the mean difference between active treatment and placebo groups. OBJECTIVE: To develop and describe the average Adjusted Symptom Score (AdSS), a new end-point reflecting symptom severity and rescue medication use in allergic rhinoconjunctivitis trials. METHODS: To calculate the AdSS, the RTSS is adjusted as follows: if a patient takes rescue medication on day d, the day's AdSS (AdSS(d)) is defined as the value of RTSS(d) or AdSS(d-1), whichever is higher. The AdSS on the following day (AdSS(d+1)) is defined as the value of RTSS(d+1) or AdSS(d), whichever is higher. The average of the daily AdSSs (during the season) was calculated post hoc for two trials investigating the efficacy of five-grass pollen sublingual immunotherapy tablets in adult and paediatric patients and compared with the ARTSS and three other outcome measures (the average Rescue Medication Score (ARMS), the ARTSS and the average Combined Score). RESULTS: The average AdSS clearly discriminated between active and placebo treatments and confirmed the original ARTSS results. Adjustment for rescue medication use decreased the observed placebo effect. CONCLUSION AND CLINICAL RELEVANCE: The average AdSS can be a valuable alternative to the ARTSS as a primary efficacy end-point in grass pollen allergic rhinoconjunctivitis trials. By adjusting the RTSS for rescue medication use, the AdSS can estimate symptom severity and the treatment effect more accurately. The AdSS is now being tested prospectively in large clinical trials.

Discrimination of auditory gratings in birds.

Auditory gratings (also called auditory ripples) are a family of complex, broadband sounds with sinusoidally modulated logarithmic amplitudes and a drifting spectral envelope. These stimuli have been studied both physiologically in mammals and psychophysically in humans. Auditory gratings share spectro-temporal properties with many natural sounds, including species-specific vocalizations and the formant transitions of human speech. We successfully trained zebra finches and budgerigars, using operant conditioning methods, to discriminate between flat-spectrum broadband noise and noises with ripple spectra of different densities that moved up or down in frequency at various rates. Results show that discrimination thresholds (minimum modulation depth) increased as a function of increasing grating periodicity and density across all species. Results also show that discrimination in the two species of birds was better at those grating periodicities and densities that are prominent in their species-specific vocalizations. Budgerigars were generally more sensitive than both zebra finches and humans. Both bird species showed greater sensitivity to descending auditory gratings, which mirrors the main direction in their vocalizations. Humans, on the other hand, showed no directional preference even though speech is somewhat downward directional. Overall, our results are suggestive of both common strategies in the processing of complex sounds between birds and mammals and specialized, species-specific variations on that processing in birds.

Implementation of pre-seasonal sublingual immunotherapy with a five-grass pollen tablet during optimal dosage assessment.

BACKGROUND: The optimal dose (300IR) of a five-grass pollen sublingual immunotherapy tablet in terms of efficacy was previously demonstrated from the first pollen season. OBJECTIVE: Here, we aim to confirm whether this dose remained optimal during the peak of the pollen season by assessing the efficacy and quality of life data. METHODS: A total of 628 subjects with grass pollen rhinoconjunctivitis were randomized in a double-blind, placebo-controlled, multi-centre, pan-European trial. Subjects received once-daily tablets (Stallergenes, Antony, France) of 100IR, 300IR, 500IR or placebo, starting 4 months before and throughout the 2005 grass pollen season. The pollen season was defined as the first day of 3 consecutive days with a grass pollen count above 30 grains/m(3) of air, recorded using Hirst-type volumetric pollen traps, to the last day before 3 consecutive days with a pollen count below 30 grains/m(3). RESULTS: The grass pollen season lasted an average of 30 days, with a peak of 12 days. The mean treatment duration before the grass pollen season was similar in the four treatment groups (121.4+/-31.1 to 128.6+/-15.4 days in the safety population). Both the 300IR and 500IR groups had highly significant improvements in Rhinoconjunctivitis Total Symptom Score (RTSS) vs. placebo at the peak pollen season (P=0.0005 and 0.0014, respectively), which agreed with improvements in RTSS in the primary evaluations. The average RTSS scores were slightly elevated during the peak pollen season in all treatment groups. The overall Rhinoconjunctivitis Quality of Life Questionnaire score confirmed the optimal dosage 300IR at peak (P<0.0001) and at the end (P< or =0.0031) of the pollen season. All doses were well tolerated. CONCLUSION: At the peak pollen season, the efficacy and quality of life data for both 300IR and 500IR groups was significantly improved vs. the placebo group. These results confirm the conclusions of the primary evaluations and validate the use of 300IR tablets for clinical practice.

Efficacy and safety of 5-grass pollen sublingual immunotherapy tablets in patients with different clinical profiles of allergic rhinoconjunctivitis.

BACKGROUND: The optimal dose of grass pollen tablets for sublingual immunotherapy (SLIT) in allergic rhinoconjunctivitis patients was previously established in a multinational, randomized, double-blind, placebo-controlled study in 628 adults. Patients were randomized to receive once-daily 5-grass pollen sublingual tablets of 100 IR (index of reactivity), 300 IR or 500 IR, or placebo starting 4 months before the pollen season. OBJECTIVE: The aim of this complementary analysis was to determine whether 300 IR 5-grass pollen SLIT-tablets is effective in different subtypes of patients who are allergic to grass pollen. METHODS: Different subgroups could be identified regarding comorbidities (with or without asthma during the grass-pollen season), sensitization (mono/polysensitization) and symptom severity. An additional exploratory analysis was performed within four subgroups based on pre-treatment assessment: Group 1=high specific IgE; Group 2=high symptom scores; Group 3=high skin sensitivity; Group 4=any of Group 1, 2 or 3. RESULTS: Asthma and sensitization status were not significant covariates as the average Rhinoconjunctivitis Total Symptom Score (RTSS) was identical for patients with and without grass-pollen asthma, as well as for mono- and polysensitized patients. Across the four subgroups, average RTSSs (+/- SD) for the optimal dosage (300 IR) were 3.91 +/- 3.16, 3.83 +/- 3.14, 2.55 +/- 2.13 and 3.61 +/- 2.97, for subgroups 1, 2, 3 and 4, respectively. ANCOVA showed that in Group 1 average RTSS did not differ significantly with different doses of SLIT. In Groups 2, 3 and 4, doses of 300 IR and 500 IR were significantly more effective than 100 IR and placebo (P< or =0.035). All doses of SLIT administered in this study can be considered safe in the patients investigated. CONCLUSIONS: The risk-benefit ratio validates the use of 300 IR tablets in clinical practice in all of these patient subgroups, regardless of severity profile, sensitization status and presence of asthma.

Agreement of efficacy assessments for five-grass pollen sublingual tablet immunotherapy.

BACKGROUND: The optimal dose of five-grass pollen sublingual tablet immunotherapy (SLIT) was established recently by the primary criteria Rhinoconjunctivitis Total Symptom Score (RTSS) from the first treatment season. Secondary and exploratory criteria, such as RTSS at peak pollen season, exploratory combined symptom and rescue medication use score, quality of life and immunological markers are calculated and described in this analysis. METHODS: Six hundred and twenty-eight patients with grass pollen rhinoconjunctivitis (> or =2 years duration) were randomized in a double-blind, placebo-controlled trial conducted in Europe. Patients received once-daily SLIT (Stallergenes, Antony, France) of 100IR, 300IR, 500IR or placebo, starting 4 months before grass pollen season and throughout the 2005 season. Patients were instructed to take rescue medication only if symptoms were severe and record symptom severity on using the RTSS. RESULTS: Both 300IR and 500IR doses significantly reduced mean RTSS at pollen peak (P = 0.0005 and P = 0.0014, respectively) and the exploratory combined score (P = 0.0001 and P = 0.0026, respectively) compared with placebo. Compared with patients in the placebo group, those who were taking the 300IR and 500IR doses reported significantly improved quality of life using the mean Rhinoconjunctivitis Quality of Life Questionnaire scores during the peak of the pollen season (P < 0.0001) and at the end of the pollen season (P = 0.0031 and P < or = 0.0001, respectively). Specific immunoglobulin G4 increased significantly depending on the SLIT dose (P < 0.0001). CONCLUSIONS: All secondary efficacy criteria, including efficacy at pollen peak, combined score, quality of life and immunological changes, indicate that 300IR tablets represent the optimal dose and suggest it is appropriate for use in clinical practice.

Resolution of SLE-related soft-tissue calcification following haematopoietic stem cell transplantation.

BACKGROUND: Calciphylaxis and calcinosis can both cause severe morbidity and mortality in patients with systemic lupus erythematosus (SLE). Haematopoietic stem cell transplantation (HSCT) has been successfully used to treat patients with refractory SLE. It was hypothesized that in calciphylaxis and calcinosis, ongoing inflammatory activity contributes to the calcium deposition in the media of small arteries, as well as perivascular and periarticular tissues. We report three patients whose soft-tissue calcification syndromes dramatically resolved after undergoing HSCT. METHODS: Three patients referred for refractory SLE underwent HSCT at a tertiary care medical center. SLE serologies and clinical features before and after HSCT were recorded. RESULTS: Despite receiving >6 months of intravenous cyclophosphamide (CYC), three SLE patients showed signs of persistent lupus activity, including severe soft-tissue calcification. The first patient was on haemodialysis and developed severe calciphylaxis with large ulcers and tissue necrosis. The second patient had calcinosis, with palpable crystals extruding from ulcers. The third patient had calcinosis characterized by subcutaneous nodules and plaques. Because prior conventional therapies had failed, the three were treated with high-dose CYC, anti-thymocyte globulin and HSCT. They have been followed post-HSCT for 26-38 months, with excellent clinical responses, including sustained resolution of skin abnormalities. CONCLUSIONS: The successful treatment of advanced calcium deposition by aggressive immune ablation underscores the contribution of SLE-mediated inflammation to soft-tissue calcification syndromes.

Temporal symmetry in primary auditory cortex: implications for cortical connectivity.

Neurons in primary auditory cortex (AI) in the ferret (Mustela putorius) that are well described by their spectrotemporal response field (STRF) are found also to have a distinctive property that we call temporal symmetry. For temporally symmetric neurons, every temporal cross-section of the STRF (impulse response) is given by the same function of time, except for a scaling and a Hilbert rotation. This property held in 85% of neurons (123 out of 145) recorded from awake animals and in 96% of neurons (70 out of 73) recorded from anesthetized animals. This property of temporal symmetry is highly constraining for possible models of functional neural connectivity within and into AI. We find that the simplest models of functional thalamic input, from the ventral medial geniculate body (MGB), into the entry layers of AI are ruled out because they are incompatible with the constraints of the observed temporal symmetry. This is also the case for the simplest models of functional intracortical connectivity. Plausible models that do generate temporal symmetry, from both thalamic and intracortical inputs, are presented. In particular, we propose that two specific characteristics of the thalamocortical interface may be responsible. The first is a temporal mismatch between the fast dynamics of the thalamus and the slow responses of the cortex. The second is that all thalamic inputs into a cortical module (or a cluster of cells) must be restricted to one point of entry (or one cell in the cluster). This latter property implies a lack of correlated horizontal interactions across cortical modules during the STRF measurements. The implications of these insights in the auditory system, and comparisons with similar properties in the visual system, are explored.

Neutrophil myeloperoxidase measurements in plasma, laminar tissue, and skin of horses given black walnut extract.

OBJECTIVE: To compare measurements of myeloperoxidase (MPO) in plasma, laminar tissues, and skin obtained from control horses and horses given black walnut heartwood extract (BWHE). ANIMALS: 22 healthy 5- to 15-year-old horses. PROCEDURES: Horses were randomly assigned to 4 groups as follows: a control group given water (n = 5) and 3 experimental groups given BWHE (17) via nasogastric intubation. Experimental groups consisted of 5, 6, and 6 horses that received BWHE and were euthanatized at 1.5, 3, and 12 hours after intubation, respectively. Control horses were euthanatized at 12 hours after intubation. Plasma samples were obtained hourly for all horses. Laminar tissue and skin from the middle region of the neck were harvested at the time of euthanasia. Plasma and tissue MPO concentrations were determined via an ELISA; tissue MPO activity was measured by use of specific immunologic extraction followed by enzymatic detection. RESULTS: Tissues and plasma of horses receiving BWHE contained significantly higher concentrations of MPO beginning at hour 3. Laminar tissue and skin from horses in experimental groups contained significantly higher MPO activity than tissues from control horses. Concentrations and activities of MPO in skin and laminar tissues were similar over time. CONCLUSIONS AND CLINICAL RELEVANCE: In horses, BWHE administration causes increases in MPO concentration and activity in laminar tissue and skin and the time of increased MPO concentration correlates with emigration of WBCs from the vasculature. These findings support the hypothesis that activation of peripheral WBCs is an early step in the pathogenesis of acute laminitis.