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Inherited CTPS1, CD27, and CD70 deficiencies in humans have revealed key factors of T‐lymphocyte expansion, a critical prerequisite for an efficient immunity to Epstein–Barr virus (EBV) infection. RASGRP1 is a T‐lymphocyte‐specific nucleotide exchange factor known to activate the pathway of MAP kinases (MAPK). A deleterious homozygous mutation in RASGRP1 leading to the loss RASGRP1 expression was identified in two siblings who both developed a persistent EBV infection leading to Hodgkin lymphoma. RASGRP1‐deficient T cells exhibited defective MAPK activation and impaired proliferation that was restored by expression of wild‐type RASGRP1. Similar defects were observed in T cells from healthy individuals when RASGRP1 was downregulated. RASGRP1‐deficient T cells also exhibited decreased CD27‐dependent proliferation toward CD70‐expressing EBV‐transformed B cells, a crucial pathway required for expansion of antigen‐specific T cells during anti‐EBV immunity. Furthermore, RASGRP1‐deficient T cells failed to upregulate CTPS1, an important enzyme involved in DNA synthesis. These results show that RASGRP1 deficiency leads to susceptibility to EBV infection and demonstrate the key role of RASGRP1 at the crossroad of pathways required for the expansion of activated T lymphocytes. Synopsis RASGRP1 deficiency is characterized by a high susceptibility to develop Epstein‐Barr virus (EBV)‐driven B‐cell lymphoproliferative disorders such as B‐cell lymphoma like Hodgkin lymphoma. This is caused by defective expansion of activated T cells required for an efficient immune response to EBV. RASGRP1 is a critical factor of T‐cell proliferation including CD27‐, CD70‐ and CTPS1‐dependent pathways. RASGRP1 is required for expression of genes involved cell proliferation. This study emphasizes that T‐cell expansion is a critical step in immunity to EBV. Graphical Abstract RASGRP1 deficiency is characterized by a high susceptibility to develop Epstein‐Barr virus (EBV)‐driven B‐cell lymphoproliferative disorders such as B‐cell lymphoma like Hodgkin lymphoma. This is caused by defective expansion of activated T cells required for an efficient immune response to EBV.

Primary immune thrombocytopenia (ITP) is a disorder caused by autoantibody-mediated platelet destruction and decreased platelet production. Rituximab, a B cell-depleting agent, has become the first-line treatment for ITP; however, patients with refractory disease usually require splenectomy. We identified antibody-secreting cells as the major splenic B cell population that is resistant to rituximab. The phenotype, antibody specificity, and gene expression profile of these cells were characterized and compared to those of antibody-secreting cells from untreated ITP spleens and from healthy tissues. Antiplatelet-specific plasma cells (PC) were detected in the spleens of patients with ITP up to 6 months after rituximab treatment, and the PC population displayed a long-lived program similar to the one of bone marrow PC, thus explaining for most of these patients the absence of response to rituximab and the response to splenectomy. When analyzed by multiplex PCR at the single-cell level, normal splenic PC showed a markedly different gene expression profile, with an intermediate signature, including genes characteristic of both long-lived PC and proliferating plasmablasts. Surprisingly, long-lived PC were not detected in untreated ITP spleens. These results suggest that the milieu generated by B cell depletion promotes the differentiation and settlement of long-lived PC in the spleen.

The coronavirus disease 2019 (COVID-19) pandemic has highlighted bottlenecks in large-scale, frequent testing of populations for infections. Polymerase chain reaction (PCR)-based diagnostic tests are expensive, reliant on centralized labs, can take days to deliver results, and are prone to backlogs and supply shortages. Antigen tests that bind and detect the surface proteins of a virus are rapid and scalable but suffer from high false negative rates. To address this problem, an inexpensive, simple, and robust 60-minute do-it-yourself (DIY) workflow to detect viral RNA from nasal swabs or saliva with high sensitivity (0.1 to 2 viral particles/μL) and specificity (>97% true negative rate) utilizing reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed. ALERT (Accessible LAMP-Enabled Rapid Test) incorporates the following features: (1) increased shelf-life and ambient temperature storage, compared to liquid reaction mixes, by using wax layers to isolate enzymes from other reagents; (2) improved specificity compared to other LAMP end-point reporting methods, by using sequence-specific QUASR (quenching of unincorporated amplification signal reporters); (3) increased sensitivity, compared to methods without purification through use of a magnetic wand to enable pipette-free concentration of sample RNA and cell debris removal; (4) quality control with a nasopharyngeal-specific mRNA target; and (5) co-detection of other respiratory viruses, such as influenza B, by multiplexing QUASR-modified RT-LAMP primer sets. The flexible nature of the ALERT workflow allows easy, at-home and point-of-care testing for individuals and higher-throughput processing for labs and hospitals. With minimal effort, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific primer sets can be swapped out for other targets to repurpose ALERT to detect other viruses, microorganisms, or nucleic acid-based markers.

Background Granulomatous disease (GD) will develop in a subset of patients with common variable immunodeficiency (CVID). Little is known about the efficacy of therapeutic agents used for treating this disorder. Objective To evaluate the efficacy of immunosuppressive drugs with the help of a set of clinical, biological and radiological criteria. Method Clinical and laboratory features of CVID patients were collected from the French DEFI cohort, a prospective study on adults with hypogammaglobulinemia. The medical charts of 55 patients (93 %) of the GD cohort were reviewed. Results Among 436 subjects with CVID, 59 patients (13.5 %) were diagnosed with GD. Of the 55 patients in whom medical charts were available, 32 patients received treatment for the granulomatous disease. Corticosteroids were the most frequently used drug. Complete response to treatment was infrequent. It was achieved with corticosteroids, cyclophosphamide, hydroxychloroquine, rituximab and methotrexate. Azathioprine, cyclosporine, mycophenolate mofetil, sirolimus, infliximab and thalidomide led to partial or absence of response. Complete and partial responses were observed in lymph nodes, lungs, liver, skin, bone marrow and central nervous system. Absent of response for gastrointestinal tract granulomas was noted in all cases of treatment attempt. Conclusion CVID patients with GD exhibit a particular biological phenotype. Treatment should be considered in any symptomatic patient or if there is evidence of organ dysfunction. Corticosteroids are the drug of choice in most instances but response to treatment is often unsatisfactory.

Inborn errors of immunity (IEI) are a heterogeneous entity with an increasing number of late diagnoses. Besides infections, inflammatory manifestations are a growing part of the clinical landscape of IEI. These complications are of unknown causes and often lead to the prescription of immunosuppressive agents that worsen the underlying immune defect. We here report the case of an adult patient diagnosed with chronic Human Adenovirus C-1 arthritis in the setting of primary agammaglobulinemia. Metagenomic next-generation sequencing led to the correct diagnosis and high-dose intravenous immunoglobulins resulted in complete recovery. This observation gives new insights into adenoviral immunity and underlines the importance of metagenomics in the diagnosis of inflammatory manifestations in immunocompromised patients.

Whipple’s Disease is a rare systemic infectious disease caused by the ubiquitous actinomycetes Tropheryma whipplei (T. whipplei). We report herein a rare case of a cutaneous granulo matosis with hypercalcemia as an unusual presenting feature of Whipple’s disease. The diagnosis of the bacteria was obtained from skin and inguinal lymph node biopsy (16 rDNA PCR screening and histological examination using PAS staining). T. whipplei was also identified on saliva and stool specimens, using specific PCR and colonic biopsies. Treatment with hydroxychloroquine and doxycycline allowed a rapid resolution of symptoms with a complete recovery.

ObjectivePatients with X linked agammaglobulinemia are susceptible to enterovirus (EV) infections. Similarly, severe EV infections have been described in patients with impaired B-cell response following treatment with anti-CD20 monoclonal antibodies (mAbs), mostly in those treated for haematological malignancies. We aimed to describe severe EV infections in patients receiving anti-CD20 mAbs for immune-mediated inflammatory diseases (IMIDs).MethodsPatients were included following a screening of data collected through the routine surveillance of EV infections coordinated by the National Reference Center and a review of the literature. Additionally, neutralising antibodies were assessed in a patient with chronic EV-A71 meningoencephalitis.ResultsNine original and 17 previously published cases were retrieved. Meningoencephalitis (n=21/26, 81%) associated with EV-positive cerebrospinal fluid (n=20/22, 91%) was the most common manifestation. The mortality rate was high (27%). EV was the only causal agents in all reported cases. Patients received multiple anti-CD20 mAbs infusions (median 8 (5–10)), resulting in complete B-cell depletion and moderate hypogammaglobulinemia (median 4.9 g/L (4.3–6.7)), and had limited concomitant immunosuppressive treatments. Finally, in a patient with EV-A71 meningoencephalitis, a lack of B-cell response to EV was shown.ConclusionEV infection should be evoked in patients with IMIDs presenting with atypical organ involvement, especially meningoencephalitis. Anti-CD20 mAbs may lead to impaired B-cell response against EV, although an underlying primary immunodeficiency should systematically be discussed.

Introduction The prognosis of thrombotic thrombocytopenic purpura (TTP) has considerably improved since the introduction of plasma exchange (PEX) therapy. However, unresponsive thrombotic thrombocytopenic purpura (Un-TTP) still carries high morbidity and mortality rates, indicating a need for early specific treatments. Patients and Methods In a retrospective study including consecutive adults with TTP admitted between January 1997 and January 2011 in a teaching hospital intensive care unit (ICU), our objective here is to identify early clinical and laboratory features predicting Un-TTP. Patients who responded to plasma exchange and steroids ( N  = 49) were compared with patients with unresponsive TTP defined as requirement for other treatments, protracted course, or death ( N  = 37, 43 %). Results Hospital mortality was 24.3 % in the Un-TTP group. Variables associated with Un-TTP on univariate logistic regression were older age, cardiac involvement, neurological involvement, higher anti-a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS13) immunoglobulin G (IgG) titer, lower platelet counts starting on day 2, higher Sequential Organ Failure Assessment (SOFA) scores starting on day 3, need for higher plasma volumes to obtain remission, and greater use of adjuvant treatments and life-sustaining interventions. Multivariate logistic regression identified four factors independently associated with Un-TTP: age over 60 years [odds ratio (OR) 7.90; 95 % confidence interval (95 % CI) 1.06–78.34], cardiac (OR 5.17; 95 % CI 1.63–16.39) or neurological (OR 8.04; 95 % CI 1.27–51.03) manifestations at diagnosis, and day 2 platelet count less than 15 G/l (OR 3.88; 95 % CI 1.30–11.62). Conclusion Therapeutic intensification starting on day 3 or even earlier in patients with the independent risk factors for unresponsive TTP identified in our study deserves evaluation in a multicenter prospective study.

Background Angioimmunoblastic T‐cell lymphoma (AITL) is one of the most frequent peripheral T‐cell lymphomas (PTCL) in western countries. Skin involvement is common and may reveal the malignancy. Despite its frequency, skin involvement in AITL has been poorly described. Objectives We aimed to analyze the cutaneous expression of PTCL of TFH origin and its prognostic impact. Methods We conducted a multicenter retrospective cohort study by retrieving histopathological reports including the mention ‘AITL’ or ‘PTCL with T‐follicular helper phenotype’ (PTCL‐TFH) from five French tertiary hospital centers. Results From 2000 to 2022, we reviewed 382 histopathological records and identified 52 AITL cases and 5 PTCL‐TFH cases with cutaneous involvement. Thirty‐two (56%) patients were males with a mean age of 63 years. Fifty‐six (98%) patients presented with lymphadenopathy, 32 (56%) splenomegaly and 17 (30%) hepatomegaly. B signs were present in 34 (60%) patients. Skin lesions were present on the lower limbs in 44 (77%) patients, trunk in 38 (67%) patients, upper limbs in 35 (61%) and head in 27 (47%). Macules and papules were the most frequent lesions found in 47 (82%) patients, followed by nodules in 10 (17%) patients, erythemato‐squamous plaques in 10 (17%) patients, purpura in 9 (16%), urticaria in 9 (16%) and blisters in 5 (9%) patients. Erythroderma affected seven patients (12%). A skin biopsy was taken in 50 patients and revealed a specific lymphomatous infiltrate in 36 cases. A dominant skin T‐cell clone was detected in 13 out of 17 (76%) patients. Among the 14 patients with a nonspecific dermatitis, various histopathological patterns were observed including interface dermatitis, psoriasiform dermatitis, vasculitis, bullous dermatitis, granulomatous dermatitis and thrombotic vasculopathy. After a median follow‐up of 24 months (range, 0–121 months), median overall survival was 121 months (95% CI, 25.2–NA). At last follow‐up, 33 patients (58%) were alive, 20 (35%) were in complete remission and 7 (12%) were in partial remission; 30 (53%) patients experienced at least one relapse, including nodal relapses in 24 (80%) cases and cutaneous relapses in 12 (40%). Conclusions This study revealed the deep heterogeneity of skin presentations in AITL. Atypical skin presentations were common and included blistering, purpuric and psoriasiform eruptions.