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1. The resting membrane potential of freshly purified normodense human eosinophils bathed in and dialysed with quasi-physiological solutions was -63 + 2 mV (n = 100). 2. In voltage-clamp mode with quasi-physiological internal and external solutions, voltage steps from the holding potential of -60 mV to levels positive to +20 mV resulted in development of a quasi-instantaneous outward current and a slowly developing outward current. The instantaneous current was absent when the cells were bathed in and dialysed with K+-free solution.3. The slow outward current persisted following simultaneous replacement of K+, Na+ and most of the Cl-with largely impermeant ions (tetraethylammonium, N-methyl-D-glucamine and methanesulphonate) and was augmented when the cell was dialysed with a solution of increased buffering capacity for protons. The observed reversal potential of the current closely followed the hydrogen equilibrium potential over a wide range of internal-external pH combinations, indicating that the conductance underlying the slow outward current was highly selective for H+ ions. 4. Acidification of the pipette solution (increasing [H+]1) augmented the outward H+ current and shifted its activation range negatively, whilst acidification of the external solution had the opposite effect. The voltage dependence of the current is modulated by the transmembrane pH gradient so that only outward current could be activated. However, when the outward current was activated by a voltage step, rapid acidification of external solution produced an inward H+ current which rapidly deactivated. 5. The proton current was reversibly inhibited in a voltage-dependent manner by extracellular application of Zn2+. The apparent dissociation constants were 8 nm (at +40 mV), 36 nm (at +70 mV) and 200 nm (at +100 mV).6. The proton current was augmented by exposure to 10 ,UM arachidonic acid. This augmentation consisted of a shift of the voltage dependence of activation to more negative potentials and enhancement of maximum conductance (H,max Assessment of the role of the eosinophil in health and disease eosinophils are now incriminated as important effector cells has proved difficult because these cells constitute only a in a number of diverse human diseases. These include the small percentage of the total leucocyte population. This host response to parasite infestation and tumours, the contrasts with the relatively sophisticated understanding reaction to transplanted tissues, and both allergic and nonthat exists for the more abundant neutrophil. Nevertheless, allergic inflammatory reactions of the major organ systems (reviewed by Spry, 1988).* To whom correspondence should be addressed. Receptor-directed stimulation of eosinophils and neutrophils leads to the release of a wide repertoire of chemical mediators. Some of these exist preformed within secretory granules, whilst others, such as eicosanoids and oxidants, are generated de novo when the cell is stimulated. Compared with neutrophils, there is a poor understanding of the events that...

BACKGROUND-Rheumatoid arthritis, like many inflammatory diseases, is characterized by episodes of quiescence and exacerbation (flares). The molecular events leading to flares are unknown.METHODS-We established a clinical and technical protocol for repeated home collection of blood in patients with rheumatoid arthritis to allow for longitudinal RNA sequencing (RNA-seq). Specimens were obtained from 364 time points during eight flares over a period of 4 years in our index patient, as well as from 235 time points during flares in three additional patients. We identified transcripts that were differentially expressed before flares and compared these with data from synovial single-cell RNA-seq. Flow cytometry and sorted-blood-cell RNA-seq in additional patients were used to validate the findings. RESULTS-Consistent changes were observed in blood transcriptional profiles 1 to 2 weeks before a rheumatoid arthritis flare. B-cell activation was followed by expansion of circulating CD45−CD31−PDPN+ preinflammatory mesenchymal, or PRIME, cells in the blood from patients with rheumatoid arthritis; these cells shared features of inflammatory synovial fibroblasts. Levels of circulating PRIME cells decreased during flares in all 4 patients, and flow cytometry and sorted-cell RNA-seq confirmed the presence of PRIME cells in 19 additional patients with rheumatoid arthritis. CONCLUSIONS-Longitudinal genomic analysis of rheumatoid arthritis flares revealed PRIME cells in the blood during the period before a flare and suggested a model in which these cells

Dynamic post-transcriptional control of RNA expression by RNA-binding proteins (RBPs) is critical during immune response. ZFP36 RBPs are prominent inflammatory regulators linked to autoimmunity and cancer, but functions in adaptive immunity are less clear. We used HITS-CLIP to define ZFP36 targets in mouse T cells, revealing unanticipated actions in regulating T-cell activation, proliferation, and effector functions. Transcriptome and ribosome profiling showed that ZFP36 represses mRNA target abundance and translation, notably through novel AU-rich sites in coding sequence. Functional studies revealed that ZFP36 regulates early T-cell activation kinetics cell autonomously, by attenuating activation marker expression, limiting T cell expansion, and promoting apoptosis. Strikingly, loss of ZFP36 in vivo accelerated T cell responses to acute viral infection and enhanced anti-viral immunity. These findings uncover a critical role for ZFP36 RBPs in restraining T cell expansion and effector functions, and suggest ZFP36 inhibition as a strategy to enhance immune-based therapies.

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The results are consistent with an autoimmune etiology in a subset of cases of Tourette's syndrome.

Dynamic post-transcriptional control of RNA expression by RNA-binding proteins (RBPs) is critical during immune response. ZFP36 RBPs are prominent inflammatory regulators linked to autoimmunity and cancer, but functions in adaptive immunity are less clear. We used HITS-CLIP to define ZFP36 targets in T-cells, which revealed unanticipated actions in regulating T-cell activation, proliferation, and effector functions. Transcriptome and ribosome profiling showed that ZFP36 represses mRNA target abundance and translation, notably through a novel class of AU-rich sites in coding sequence. Functional studies revealed that ZFP36 regulates early T-cell activation kinetics in a cell autonomous manner, by attenuating activation marker expression, limiting T-cell expansion, and promoting apoptosis. Strikingly, loss of ZFP36 in vivo accelerated T-cell responses to acute viral infection, and enhanced anti-viral immunity. These findings uncover a critical role for ZFP36 RBPs in restraining T-cell expansion and effector functions, and suggest ZFP36 inhibition as a novel strategy to enhance immune-based therapies.

dsDNA were shown in 64% of patients with autoimmune To determine the significance of antibodies to singlehepatitis, 46% with cryptogenic hepatitis, and 43% with stranded (anti-ssDNA) and double-stranded DNA (antichronic hepatitis B. 8 Tsuchiya and colleagues, using an ELISA dsDNA) in antinuclear antibody (ANA)-positive type 1 autobased on a similar substrate, found anti-dsDNA in 48% of immune hepatitis, sera from 53 patients were tested by patients with autoimmune hepatitis and 17% of patients with enzyme immunosorbent assay (ELISA) and indirect immunoprimary biliary cirrhosis. 9 Testing of the same sera by an fluorescence using the Crithidia luciliae substrate. Antiindirect immunofluorescence assay based on the kinetoplast dsDNA were detected in 18 patients (34%) by ELISA and 12of Crithidia luciliae, a pure source of dsDNA, disclosed simipatients (23%) by the Crithidia-based assay. Twenty patients lar results. 9 A smaller study from Australia, using an immuwith anti-dsDNA by either assay (38%) had higher serum nofluorescence assay based on Crithidia luciliae, also showed levels of immunoglobulin G (3971 { 270 mg/dL vs. 3201 { a significant serologic overlap with SLE.10 247 mg/dL, P Å .05) than seronegative patients. They also Methodological differences can affect the detection of antihad human leukocyte antigen (HLA) DR4 more commonly dsDNA and the assessment of its clinical significance. Conthan other patients (83% vs. 41%, P Å .006) and normal tamination of the dsDNA substrate with single-stranded DNA subjects (83% vs. 30%, P Å .00007). In contrast to patients (ssDNA) may result in false positive results in some inseropositive by the Crithidia-based assay, those seropositive stances. 5 Differences in antibody avidity and class may also by ELISA failed corticosteroid therapy more commonly (24% influence detection. ELISAs detect antibodies of low avidity vs. 3%, P Å .04). Anti-ssDNA were found in 45 patients that may predominate in diseases other than SLE whereas (85%) and they did not distinguish patients with different the Crithidia assay may detect only high avidity antibodies clinical features or outcomes. We conclude that anti-dsDNA of greater pathogenic importance. outcome to determine the clinical pertinence of the findings and we evaluate the association between antibody expression Antibodies to double-stranded DNA (anti-dsDNA) have a and the known genetic risk factors for type 1 autoimmune high specificity for the diagnosis of systemic lupus erythema-hepatitis. We also determine the frequency of antibodies to tosus (SLE) and they correlate closely with disease activity.