Understanding patient-derived tumor organoid growth through an integrated imaging and mathematical modeling framework.

Patient-derived tumor organoids (PDTOs) are novel cellular models that maintain the genetic, phenotypic and structural features of patient tumor tissue and are useful for studying tumorigenesis and drug response. When integrated with advanced 3D imaging and analysis techniques, PDTOs can be used to establish physiologically relevant high-throughput and high-content drug screening platforms that support the development of patient-specific treatment strategies. However, in order to effectively leverage high-throughput PDTO observations for clinical predictions, it is critical to establish a quantitative understanding of the basic properties and variability of organoid growth dynamics. In this work, we introduced an innovative workflow for analyzing and understanding PDTO growth dynamics, by integrating a high-throughput imaging deep learning platform with mathematical modeling, incorporating flexible growth laws and variable dormancy times. We applied the workflow to colon cancer organoids and demonstrated that organoid growth is well-described by the Gompertz model of growth. Our analysis showed significant intrapatient heterogeneity in PDTO growth dynamics, with the initial exponential growth rate of an organoid following a lognormal distribution within each dataset. The level of intrapatient heterogeneity varied between patients, as did organoid growth rates and dormancy times of single seeded cells. Our work contributes to an emerging understanding of the basic growth characteristics of PDTOs, and it highlights the heterogeneity in organoid growth both within and between patients. These results pave the way for further modeling efforts aimed at predicting treatment response dynamics and drug resistance timing.

Optical wavefront phase-tilt measurement using Si-photonic waveguide grating couplers.

Silicon photonic wavefront phase-tilt sensors for wavefront monitoring using surface coupling grating arrays are demonstrated. The first design employs the intrinsic angle dependence of the grating coupling efficiency to determine local wavefront tilt, with a measured sensitivity of 7 dB/°. The second design connects four gratings in an interferometric waveguide circuit to determine incident wavefront phase variation across the sensor area. In this device, one fringe spacing corresponds to 2° wavefront tilt change. These sensor elements sample a wavefront incident on the chip surface without the use of bulk optic elements, fiber arrays, or imaging arrays. Both sensor elements are less than 60 µm across and are potential unit cell sensor elements for large arrays that monitor wavefront shape across an image or pupil plane in adaptive optics systems for free-space optical communications, astronomy, and beam pointing applications.

Whole-exome sequencing of T- B+ severe combined immunodeficiency in Egyptian infants, JAK3 predominance and novel variants.

Severe combined immunodeficiency (SCID) is fatal if not treated with immune reconstitution. In Egypt, T- B+ SCID accounts for 38·5% of SCID diagnoses. An accurate genetic diagnosis is essential for choosing appropriate treatment modalities and for offering genetic counseling to the patient's family. The objectives of this study were to describe the clinical, immunological and molecular characteristics of a cohort of twenty Egyptian patients with T- B+ SCID. The initial diagnosis (based on clinical features and flow cytometry) was followed by molecular investigation (whole-exome sequencing). All patients had the classic clinical picture for SCID, including failure to thrive (n = 20), oral candidiasis (n = 17), persistent diarrhea (n = 14), pneumonia (n = 13), napkin dermatitis (n = 10), skin rash (n = 7), otitis media (n = 3) and meningitis (n = 2). The onset of manifestations was at the age of 2·4 ± 1·6 months and diagnosis at the age of 6·7 ± ·5 months, giving a diagnostic delay of 4·3 months. JAK3 gene variants were most frequent (n = 12) with three novel variants identified, followed by IL2Rγ variants (n = 6) with two novel variants. IL7Rα and CD3ε variants were found once, with a novel variant each. T- B+ NK- SCID accounted for approximately 90% of the Egyptian patients with T- B+ SCID. Of these T- B+ NK- SCID cases, 60% were autosomal recessive syndromes caused by JAK3 mutations and 30% were X-linked syndromes. It might be useful to sequence the JAK3 gene (i.e. targeted Sanger sequencing) in all T- B+ SCID patients, especially after X-linked SCID has been ruled out. Hence, no more than 10% of T- B+ SCID patients might require next-generation for a molecular diagnosis.

Improved Access to Organo-Soluble Di- and Tetrafluoridochlorate(I)/(III) Salts.

A facile one-pot gram-scale synthesis of tetraalkylammonium tetrafluoridochlorate(III) [cat][ClF4 ] ([cat]=[NEt3 Me]+ , [NEt4 ]+ ) is described. An acetonitrile solution of the corresponding alkylammonium chloride salt is fluorinated with diluted fluorine at low temperatures. The reaction proceeds via the [ClF2 ]- anion which is structurally characterized for the first time. The potential application of [ClF4 ]- salts as fluorinating agents is evaluated by the reaction with diphenyl disulfide, Ph2 S2 , to pentafluorosulfanyl benzene, PhSF5 . The CN moieties in acetonitrile and [B(CN)4 ]- are transferred in CF3 groups. Exposure of carbon monoxide, CO, leads to the formation of carbonyl fluoride, COF2 , and elemental gold is dissolved under the formation of tetrafluoridoaurate [AuF4 ]- .

Phenotypical heterogeneity in RAG-deficient patients from a highly consanguineous population.

Mutations affecting recombination activation genes RAG1 and RAG2 are associated with variable phenotypes, depending on the residual recombinase activity. The aim of this study is to describe a variety of clinical phenotypes in RAG-deficient patients from the highly consanguineous Egyptian population. Thirty-one patients with RAG mutations (from 28 families) were included from 2013 to 2017. On the basis of clinical, immunological and genetic data, patients were subdivided into three groups; classical T- B- severe combined immunodeficiency (SCID), Omenn syndrome (OS) and atypical SCID. Nineteen patients presented with typical T- B- SCID; among these, five patients carried a homozygous RAG2 mutation G35V and five others carried two homozygous RAG2 mutations (T215I and R229Q) that were detected together. Four novel mutations were reported in the T- B- SCID group; three in RAG1 (A565P, N591Pfs*14 and K621E) and one in RAG2 (F29S). Seven patients presented with OS and a novel RAG2 mutation (C419W) was documented in one patient. The atypical SCID group comprised five patients. Two had normal B cell counts; one had a previously undescribed RAG2 mutation (V327D). The other three patients presented with autoimmune cytopaenias and features of combined immunodeficiency and were diagnosed at a relatively late age and with a substantial diagnostic delay; one patient had a novel RAG1 mutation (C335R). PID disorders are frequent among Egyptian children because of the high consanguinity. RAG mutations stand behind several variable phenotypes, including classical SCID, OS, atypical SCID with autoimmunity and T- B+ CID.

A novel method for automated assessment of megakaryocyte differentiation and proplatelet formation.

Transfusion of platelet concentrates represents an important treatment for various bleeding complications. However, the short half-life and frequent contaminations with bacteria restrict the availability of platelet concentrates and raise a clear demand for platelets generated ex vivo. Therefore, in vitro platelet generation from megakaryocytes represents an important research topic. A vital step for this process represents accurate analysis of thrombopoiesis and proplatelet formation, which is usually conducted manually. We aimed to develop a novel method for automated classification and analysis of proplatelet-forming megakaryocytes in vitro. After fluorescent labelling of surface and nucleus, MKs were automatically categorized and analysed with a novel pipeline of the open source software CellProfiler. Our new workflow is able to detect and quantify four subtypes of megakaryocytes undergoing thrombopoiesis: proplatelet-forming, spreading, pseudopodia-forming and terminally differentiated, anucleated megakaryocytes. Furthermore, we were able to characterize the inhibitory effect of dasatinib on thrombopoiesis in more detail. Our new workflow enabled rapid, unbiased, quantitative and qualitative in-depth analysis of proplatelet formation based on morphological characteristics. Clinicians and basic researchers alike will benefit from this novel technique that allows reliable and unbiased quantification of proplatelet formation. It thereby provides a valuable tool for the development of methods to generate platelets ex vivo and to detect effects of drugs on megakaryocyte differentiation.

Cylindrospermopsin toxicity in mice following a 90-d oral exposure.

Cylindrospermopsin (CYN) is a toxin associated with numerous species of freshwater cyanobacteria throughout the world. It is postulated to have caused an episode of serious illnesses in Australia through treated drinking water, as well as lethal effects in livestock exposed to water from farm ponds. Toxicity included effects indicative of both hepatic and renal dysfunction. In humans, symptoms progressed from initial hepatomegaly, vomiting, and malaise to acidosis and hypokalemia, bloody diarrhea, and hyperemia in mucous membranes. Laboratory animal studies predominantly involved the intraperitoneal (i.p.) route of administration and confirmed this pattern of toxicity with changes in liver enzyme activities and histopathology consistent with hepatic injury and adverse renal effects. The aim of this study was designed to assess subchronic oral exposure (90 d) of purified CYN from 75 to 300 µg/kg/d in mouse. At the end of the dosing period, examinations of animals noted (1) elevated organ to body weight ratios of liver and kidney at all dose levels, (2) treatment-related increases in serum alanine aminotransferase (ALT) activity, (3) decreased blood urea nitrogen (BUN) and cholesterol concentrations in males, and (4) elevated monocyte counts in both genders. Histopathological alterations included hepatocellular hypertrophy and cord disruption in the liver, as well as renal cellular hypertrophy, tubule dilation, and cortical tubule lesions that were more prominent in males. A series of genes were differentially expressed including Bax (apoptosis), Rpl6 (tissue regeneration), Fabp4 (fatty acid metabolism), and Proc (blood coagulation). Males were more sensitive to many renal end points suggestive of toxicity. At the end of exposure, toxicity was noted at all dose levels, and the 75 µg/kg group exhibited significant effects in liver and kidney/body weight ratios, reduced BUN, increased serum monocytes, and multiple signs of histopathology indicating that a no-observed-adverse-effect level could not be determined for any dose level.

[Provision of palliative care for people with advanced dementia]. / Palliativversorgung von Menschen mit fortgeschrittener Demenz.

As a result of a literature-based expert process, this review provides an overview about the principles of palliative care for people with advanced dementia that are relevant for clinical practice. In particular, the indications, impact and aims of palliative care for advanced dementia are described. Life-prolonging measures and management of symptoms at the end of life are discussed. Furthermore, the overview focuses on the legal basis of decision making.

Novel approaches and perspectives in allergen immunotherapy.

In this review, we report on relevant current topics in allergen immunotherapy (AIT) which were broadly discussed during the first Aarhus Immunotherapy Symposium (Aarhus, Denmark) in December 2015 by leading clinicians, scientists and industry representatives in the field. The aim of this symposium was to highlight AIT-related aspects of public health, clinical efficacy evaluation, mechanisms, development of new biomarkers and an overview of novel therapeutic approaches. Allergy is a public health issue of high socioeconomic relevance, and development of evidence-based action plans to address allergy as a public health issue ought to be on national and regional agendas. The underlying mechanisms are in the focus of current research that lays the ground for innovative therapies. Standardization and harmonization of clinical endpoints in AIT trials as well as current knowledge about potential biomarkers have substantiated proof of effectiveness of this disease-modifying therapeutic option. Novel treatments such as peptide immunotherapy, intralymphatic immunotherapy and use of recombinant allergens herald a new age in which AIT may address treatment of allergy as a public health issue by reaching a large fraction of patients.

A critical review of the postulated role of the non-essential amino acid, ß-N-methylamino-L-alanine, in neurodegenerative disease in humans.

The compound BMAA (ß-N-methylamino-L-alanine) has been postulated to play a significant role in four serious neurological human diseases: Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC) found on Guam, and ALS, Parkinsonism, and dementia that occur globally. ALS/PDC with symptoms of all three diseases first came to the attention of the scientific community during and after World War II. It was initially associated with cycad flour used for food because BMAA is a product of symbiotic cycad root-dwelling cyanobacteria. Human consumption of flying foxes that fed on cycad seeds was later suggested as a source of BMAA on Guam and a cause of ALS/PDC. Subsequently, the hypothesis was expanded to include a causative role for BMAA in other neurodegenerative diseases including Alzheimer's disease (AD) through exposures attributed to proximity to freshwaters and/or consumption of seafood due to its purported production by most species of cyanobacteria. The hypothesis that BMAA is the critical factor in the genesis of these neurodegenerative diseases received considerable attention in the medical, scientific, and public arenas. This review examines the history of ALS/PDC and the BMAA-human disease hypotheses; similarities and differences between ALS/PDC and the other diseases with similar symptomologies; the relationship of ALS/PDC to other similar diseases, studies of BMAA-mediated effects in lab animals, inconsistencies and data gaps in the hypothesis; and other compounds and agents that were suggested as the cause of ALS/PDC on Guam. The review concludes that the hypothesis of a causal BMAA neurodegenerative disease relationship is not supported by existing data.

Behavioral variant frontotemporal dementia: advanced disease stages and death. A step to palliative care.

OBJECTIVE: The aim of the present study was to gain insight into the living and care situation in advanced behavioral variant frontotemporal dementia (bvFTD), to describe symptoms and findings in advanced bvFTD, and to evaluate somatic comorbidities and circumstances of death. METHODS: Standardized interviews were conducted with family caregivers of 83 patients with bvFTD. Forty-four percent of the patients were already deceased at the time of the interview. RESULTS: At the time of the interview or death, respectively, 47% of the patients lived in a nursing home. The median time between symptom onset and nursing home admission was 5.0 ± 5.5 years. In moderate and severe dementia stages almost all patients suffered from severe disabilities including impairment of language, gait, swallowing, and of the ability to care for themselves. Sixteen percent of the patients had got enteral tube feeding. Comorbid somatic diseases were diagnosed in 46% of the patients. Twenty-three percent of the deceased patients had been admitted into a hospital before death. Cardiovascular disease and respiratory disease, mostly pneumonia, were the most frequent causes of death. CONCLUSIONS: Advanced bvFTD is characterized by severe cognitive impairment and physical disabilities. BvFTD leads to a premature death. Our findings stress the importance of strategies that maximize patient comfort in advanced disease stages and allow for a peaceful death. Copyright © 2016 John Wiley & Sons, Ltd.

Suicide and assisted dying in dementia: what we know and what we need to know. A narrative literature review.

BACKGROUND: Evidence-based data on prevalence and risk factors of suicidal intentions and behavior in dementia are as scarce as the data on assisted dying. The present literature review aimed on summarizing the current knowledge and provides a critical discussion of the results. METHODS: A systematic narrative literature review was performed using Medline, Cochrane Library, EMBASE, PSYNDEX, PSYCINFO, Sowiport, and Social Sciences Citation Index literature. RESULTS: Dementia as a whole does not appear to be a risk factor for suicide completion. Nonetheless some subgroups of patients with dementia apparently have an increased risk for suicidal behavior, such as patients with psychiatric comorbidities (particularly depression) and of younger age. Furthermore, a recent diagnosis of dementia, semantic dementia, and previous suicide attempts most probably elevate the risk for suicidal intentions and behavior. The impact of other potential risk factors, such as patient's cognitive impairment profile, behavioral disturbances, social isolation, or a biomarker based presymptomatic diagnosis has not yet been investigated. Assisted dying in dementia is rare but numbers seem to increase in regions where it is legally permitted. CONCLUSION: Most studies that had investigated the prevalence and risk factors for suicide in dementia had significant methodological limitations. Large prospective studies need to be conducted in order to evaluate risk factors for suicide and assisted suicide in patients with dementia and persons with very early or presymptomatic diagnoses of dementia. In clinical practice, known risk factors for suicide should be assessed in a standardized way so that appropriate action can be taken when necessary.

Effects of maternal high-fat diet and sedentary lifestyle on susceptibility of adult offspring to ozone exposure in rats.

Epidemiological and experimental data suggest that obesity exacerbates the health effects of air pollutants such as ozone (O3). Maternal inactivity and calorically rich diets lead to offspring that show signs of obesity. Exacerbated O3 susceptibility of offspring could thus be manifested by maternal obesity. Thirty-day-old female Long-Evans rats were fed a control (CD) or high-fat (HF) (60% calories) diet for 6 wks and then bred. GD1 rats were then housed with a running wheel (RW) or without a wheel (SED) until parturition, creating four groups of offspring: CD-SED, CD-RW, HF-SED and HF-RW. HF diet was terminated at PND 35 and all offspring were placed on CD. Body weight and %fat of dams were greatest in order; HF-SED > HF-RW > CD-SED > CD-RW. Adult offspring were exposed to O3 for two consecutive days (0.8 ppm, 4 h/day). Glucose tolerance tests (GTT), ventilatory parameters (plethysmography), and bronchoalveolar fluid (BALF) cell counts and protein biomarkers were performed to assess response to O3. Exercise and diet altered body weight and %fat of young offspring. GTT, ventilation and BALF cell counts were exacerbated by O3 with responses markedly exacerbated in males. HF diet and O3 led to significant exacerbation of several BALF parameters: total cell count, neutrophils and lymphocytes were increased in male HF-SED versus CD-SED. Males were hyperglycemic after O3 exposure and exhibited exacerbated GTT responses. Ventilatory dysfunction was also exacerbated in males. Maternal exercise had minimal effects on O3 response. The results of this exploratory study suggest a link between maternal obesity and susceptibility to O3 in their adult offspring in a sex-specific manner.

Effects of vitamin D supplementation on glycated haemoglobin and fasting glucose levels in hypertensive patients: a randomized controlled trial.

AIM: To investigate the efficacy of vitamin D supplementation on glycaemic control. METHODS: The Styrian Vitamin D Hypertension Trial was a single-centre, double-blind, placebo-controlled study conducted between 2011 and 2014 at the Medical University of Graz, Austria. We enrolled 200 people with arterial hypertension and 25-hydroxyvitamin D [25(OH)D] concentrations <30 ng/mL. Study participants were randomized to receive either 2800 IU of vitamin D or placebo per day for 8 weeks. The present study was a post hoc analysis that incorporated an analysis of covariance (ancova) approach, while adjusting for baseline differences. RESULTS: A total of 185 participants [mean ± standard deviation age, 60.1 ± 11.3 years; 47% women; mean 25(OH)D 21.2 ± 5.6 ng/mL, mean glycated haemoglobin (HbA1c) 44.8 ± 11.8 mmol/mol and mean body mass index 30.4 ± 5.4 kg/m(2) ] completed the trial. ancova showed a mean treatment effect [95% confidence interval (CI)] on HbA1c of -3.52 (-6.7 to -0.34) mmol/mol (p = .045). There was no difference in fasting glucose -4.7 mg/dL (95% CI -16.3 to 6.9; p = .426). CONCLUSIONS: Vitamin D supplementation in obese hypertensive patients with low 25(OH)D reduces HbA1c levels. This finding warrants further investigation into potential vitamin D effects on glucose homeostasis.

[Men who have sex with men (MSM) and HIV infection in Ouagadougou, Burkina Faso: Knowledge, attitudes, practices and seroprevalence survey]. / Les hommes qui ont des rapports sexuels avec d'autres hommes (HSH) et l'infection à VIH à Ouagadougou, Burkina Faso : connaissances, attitudes, pratiques et enquête de séroprévalence.

BACKGROUND: Like many African countries, the issue of sex between men in Burkina Faso remains taboo and sometimes result in social exclusion. This population which is vulnerable to HIV/AIDS is unknown, due to lack of scientific researches. AIM: Our study aimed to characterize knowledge, attitudes and sexual practices and to estimate HIV seroprevalence among men having sex with men (MSM) living in Ouagadougou. METHODS: A cross-sectional study was conducted in order to describe and analyze MSM living in Ouagadougou. They were recruited by snowball sampling, aged at least 18 years, and accepted to participate at the study. Data were collected by qualified interviewers through administered questionnaire face to face. HIV test was systematically proposed. RESULTS: A total of 142 MSM were recruited during the study period. The sample was mostly composed of students or pupils (60.8%), single men (91%), with age range 18-30 years (96.5%). The HIV knowledge median score was 8/10. HIV seroprevalence was 8.9% (4.5-15.4). CONCLUSION: Our study confirms the vulnerability of MSM living in Ouagadougou about HIV/AIDS given the high rate of HIV seroprevalence. Targeted interventions for prevention, care and scientific research are challenges for the authorities to sustain the achievements of the national fight against HIV and AIDS.

Cardiovascular control, autonomic function, and elite endurance performance in spinal cord injury.

We aimed to determine the relationship between level of injury, completeness of injury, resting as well as exercise hemodynamics, and endurance performance in athletes with spinal cord injury (SCI). Twenty-three elite male paracycling athletes (C3-T8) were assessed for neurological level/completeness of injury, autonomic completeness of injury, resting cardiovascular function, and time to complete a 17.3-km World Championship time-trial test. A subset were also fitted with heart rate (HR) monitors and their cycles were fitted with a global positioning systems device (n = 15). Thoracic SCI exhibited higher seated systolic blood pressure along with superior time-trial performance compared with cervical SCI (all P < 0.01). When further stratified by autonomic completeness of injury, the four athletes with cervical autonomic incomplete SCI exhibited a faster time-trial time and a higher average speed compared with cervical autonomic complete SCI (all P < 0.042). Maximum and average HR also tended to be higher in cervical autonomic incomplete vs autonomic complete. There were no differences in time-trial time, HR, or speed between thoracic autonomic complete vs incomplete SCI. In conclusion, autonomic completeness of injury and the consequent ability of the cardiovascular system to respond to exercise appear to be a critical determinant of endurance performance in elite athletes with cervical SCI.

[Genetics of dementia]. / Genetik der Demenzen.

Most psychiatric diseases in adulthood have a multifactorial origin. This also applies for most cases of dementia; however, rare familial forms of Alzheimer's disease and frontotemporal lobar degeneration follow an autosomal dominant (Mendelian) inheritance pattern. Alzheimer's disease that is caused by mutations in the genes for presenilin 1, presenilin 2 and amyloid precursor protein has an onset under the age of 65 years in most cases. Approximately 10 % of frontotemporal lobar degeneration cases display an autosomal dominant inheritance pattern. According to the current S3 guidelines on dementia of the German Association for Psychiatry, Psychotherapy and Psychosomatics and the German Society of Neurology, genetic counseling should be offered if an autosomal dominant disease pattern is suspected. Genetic counseling must conform to the German Genetic Diagnostics Act (Gendiagnostikgesetz).

[Psychosocial Aspects in Cardiac Rehabilitation: From Theory to Practice. A Position Paper From the Cardiac Rehabilitation Section of The European Association of Cardiovascular Prevention and Rehabilitation of the European Society of Cardiology].

A large body of empirical research shows that psychosocial risk factors (PSRFs) such as low socio-economic status, social isolation, stress, type-D personality, depression and anxiety increase the risk of incident coronary heart disease (CHD) and also contribute to poorer health-related quality of life (HRQoL) and prognosis in patients with establishedCHD. PSRFs may also act as barriers to lifestyle changes and treatment adherence and may moderate the effects of cardiac rehabilitation (CR). Furthermore, there appears to be a bidirectional interaction between PSRFs and the cardiovascular system. Stress, anxiety and depression affect the cardiovascular system through immune, neuroendocrine and behavioural pathways. In turn, CHD and its associated treatments may lead to distress in patients, including anxiety and depression. In clinical practice, PSRFs can be assessed with single-item screening questions, standardised questionnaires, or structured clinical interviews. Psychotherapy and medication can be considered to alleviate any PSRF-related symptoms and to enhance HRQoL, but the evidence for a definite beneficial effect on cardiac endpoints is inconclusive. A multimodal behavioural intervention, integrating counselling for PSRFs and coping with illness should be included within comprehensive CR. Patients with clinically significant symptoms of distress should be referred for psychological counselling or psychologically focused interventions and/or psychopharmacological treatment. To conclude, the success of CR may critically depend on the interdependence of the body and mind and this interaction needs to be reflected through the assessment and management of PSRFs in line with robust scientific evidence, by trained staff, integrated within the core CR team.

Fiber-chip grating coupler based on interleaved trenches with directionality exceeding 95.

We propose a fiber-chip grating coupler that interleaves the standard full and shallow etch trenches in a 220 nm thick silicon layer to provide a directionality upward exceeding 95%. By adjusting the separation between the two sets of trenches, constructive interference is achieved in the upward direction independent of the bottom oxide thickness and without any bottom reflectors, overlays, or customized etch depths. We implement a transverse subwavelength structure in the first two grating periods to minimize back-reflections. The grating coupler has a calculated coupling efficiency of CE~-1.05 dB with a 1 dB bandwidth of 30 nm and minimum feature size of 100 nm, compatible with deep-UV lithography.

Sequential allergen desensitization of basophils is non-specific and may involve p38 MAPK.

BACKGROUND: Sequential allergen desensitization provides temporary tolerance for allergic patients. We adapted a clinical protocol to desensitize human blood basophils ex vivo and investigated the mechanism and allergen specificity. METHODS: We included 28 adult, grass allergic subjects. The optimal, activating allergen concentration was determined by measuring activated CD63(+) CD193(+) SS(Low) basophils in a basophil activation test with 8 log-dilutions of grass allergen. Basophils in whole blood were desensitized by incubation with twofold to 2.5-fold increasing allergen doses in 10 steps starting at 1 : 1000 of the optimal dose. Involvement of p38 mitogen-activated protein kinase (MAPK) was assessed after 3 min of allergen stimulation (n = 7). Allergen specificity was investigated by desensitizing cells from multi-allergic subjects with grass allergen and challenging with optimal doses of grass, birch, recombinant house dust mite (rDer p2) allergen or anti-IgE (n = 10). RESULTS: Desensitization reduced the fraction of blood basophils responding to challenge with an optimal allergen dose from a median (IQR) 81.0% (66.3-88.8) to 35.4% (19.8-47.1, P < 0.0001). CD63 MFI expression was reduced from 68 248 (29 336-92 001) to 30 496 (14 046-46 179, P < 0.0001). Basophils from multi-allergic subjects were desensitized with grass allergen. Challenge with grass allergen resulted in 39.6% activation (15.8-58.3). An unrelated challenge (birch, rDer p2 or anti-IgE) resulted in 53.4% activation (30.8-66.8, P = 0.16 compared with grass). Desensitization reduced p38 MAPK phosphorylation from a median 48.1% (15.6-92.8) to 26.1% (7.4-71.2, P = 0.047) and correlated with decrease in CD63 upregulation (n = 7, r > 0.79, P < 0.05). CONCLUSION: Desensitization attenuated basophil response rapidly and non-specifically at a stage before p38 MAPK phosphorylation.