Relationships of circulating CD4+ T cell subsets and cytokines with the risk of relapse in patients with Crohn's disease.

Background and aims: We aimed to analyze circulating CD4+ T cell subsets and cytokines during the course of Crohn's disease (CD). Methods and results: CD4+ T cell subsets, ultrasensitive C-reactive protein (usCRP), and various serum cytokines (IL-6, IL-8, IL-10, IL-13, IL-17A, IL-23, TNFα, IFNγ, and TGFß) were prospectively monitored every 3 months for 1 year, using multicolor flow cytometry and an ultrasensitive Erenna method in CD patients in remission at inclusion. Relapse occurred in 35 out of the 113 consecutive patients (31%). For patients in remission within 4 months prior to relapse and at the time of relapse, there was no significant difference in Th1, Th17, Treg, and double-positive CD4+ T cell subsets co-expressing either IFNγ and FOXP3, IL-17A and FOXP3, or IFNγ and IL-17A. On the contrary, in patients who remained in remission, the mean frequency and number of double-positive IL-17A+FOXP3+ CD4+ T cells and the level of usCRP were significantly higher (p ≤ 0.01) 1 to 4 months prior to relapse. At the time of relapse, only the IL-6 and usCRP levels were significantly higher (p ≤ 0.001) compared with those patients in remission. On multivariate analysis, a high number of double-positive IL-17A+FOXP3+ CD4+ T cells (≥1.4 cells/mm3) and elevated serum usCRP (≥3.44 mg/L) were two independent factors associated with risk of relapse. Conclusions: Detection of circulating double-positive FOXP3+IL-17A+ CD4+ T cell subsets supports that T cell plasticity may reflect the inflammatory context of Crohn's disease. Whether this subset contributes to the pathogenesis of CD relapse needs further studies.

Hypersensitivity transfusion reactions to fresh frozen plasma: a retrospective analysis of the French hemovigilance network.

Few data are currently available on hypersensitivity transfusion reactions (HTRs) after exposure to fresh frozen plasma (FFP). Between 2000 and 2018, three different FFP production strategies have been used in France, leading to the concomitant use of different types of FFP. The objective of this study was to describe the rate of FFP-related HTRs and to assess the relative risk of each type of FFP. HTR following FFP transfusion between 2000 and 2018 were retrospectively extracted from the national hemovigilance database of the French National Agency for Medicines and Health Products Safety (ANSM). Temporal evolution of the incidence of reactions was modeled using logistic regression. During the study period, the overall rate of FFP-related HTRs was 52.0 (95% CI 50.2-53.9) reactions per 100,000 units of FFP issued. The rate of FFP-related HTRs progressively increased over the study period, from 28.7 (95% CI 22.8-36.0) in 2000 to 88.9 (78.8-100.3) reactions per 100,000 units of FFP issued in 2018 (OR 1.08 [1.07 - 1.09], P < .001), whereas the rate of other types of adverse transfusion reactions (ATRs) decreased. Between 2000 and 2014, its period of use, Solvent-Detergent-treated Apheresis FFP (SD-APH) was associated with the lowest risk of HTR. Our results indicate that although the rate of HTRs to FFP is low in France, the risk of having such a reaction has steadily increased between 2000 and 2018. A declarative bias is unlikely as the rate of other type of FFP-related ATRs decreased over the same period. The risk of HTRs to FFP is suggested to differ according to the processing of the FFP with a lower risk for SD-APH.

Insights into the Allergenic Potential of the Edible Yellow Mealworm (Tenebrio molitor).

The edible yellow mealworm (Tenebrio molitor), contains an extremely diverse panel of soluble proteins, including proteins with structural functions such as muscle proteins, as well as proteins involved in metabolic functions such as enzymes. Most of these proteins display a more or less pronounced allergenic character toward previously sensitized people, especially people allergic to shrimps and other shellfish. A mass spectrometry approach following the separation of a mealworm protein, extracted by sodiumdodecyl sulfate-polyacrylamide gel electrophoresis, allowed us to identify up to 106 distinct protein fractions including molecules with structural and functional functions, susceptible to developing an allergenic potential due to the possibility of immunoglobulin E-binding cross-reactions with their counterparts occurring in shellfish. In this respect, most of the sera from people allergic to shrimps reacted with the mealworm protein extract in Western blot experiments. Moreover, the potential mealworm allergens triggered the in vitro degranulation of rat leukemic basophils transfected with the human high-affinity IgE receptor (FcεRI), upon sensitization by the IgE-containing sera from people allergic to shrimps and other shellfish foods. Owing to the large repertoire of IgE-binding cross-reacting allergens the yellow mealworm shares with other phylogenetically-related groups of arthropods, it would seem prudent to inform the consumers, especially those allergic to shellfish, by appropriate labeling on edible mealworm packages about the potential risk of developing an allergic reaction.

USE OF A THRESHOLD OF INTERLEUKIN-10 AND IL-10/IL-6 RATIO IN OCULAR SAMPLES FOR THE SCREENING OF VITREORETINAL LYMPHOMA.

PURPOSE: To determine a threshold for interleukin (IL)-10 and IL-10/IL-6 ratio in the aqueous humor (AH) and the vitreous for the screening of vitreoretinal lymphoma (VRL). METHODS: One hundred nineteen patients for whom IL-10 and IL-6 in the AH and/or vitreous had been measured were included: 16 patients with a final diagnosis of VRL and 103 patients with final diagnosis of uveitis. Groups were compared according to IL-10 and IL-6 levels and demographic data. RESULTS: In patients with VRL (Group 1), mean IL-10 values were 5,636 pg/mL, and in patients with uveitis (Group 2), 6.7 pg/mL in the vitreous and 190 pg/mL in Group 1 and 8.6 pg/mL in the AH. In Group 1, the mean IL-10/IL-6 ratio was 29.02 in the vitreous and 10.9 in the AH; in Group 2, ratio was 0.1 in both humors. These values were significantly different between patients with VRL and with uveitis (P < 0.001). A cutoff of 65 pg/mL and 30 pg/mL IL-10 in the vitreous and AH, respectively, was associated with sensitivity of 93% and 78%, respectively, and specificity of 100% and 97%, respectively. A ratio higher than 1 in the vitreous had sensitivity of 93% and specificity of 100%. CONCLUSION: Vitreoretinal lymphoma diagnosis is difficult, and tools like interleukin measurements in AH and vitreous can make it easier. The use of a cutoff for IL-10 and IL-10/IL-6 ratio could allow for an earlier diagnosis that may improve prognosis.

Alteration of Natural Killer cell phenotype and function in obese individuals.

Obesity is associated with increased cancer rates and higher susceptibility to infections. The adipose tissue of obese individuals is inflammatory and may negatively impact on innate and adaptive immunity in a systemic way. Here, we explored the phenotype and function of peripheral Natural Killer (NK) cells of patients in correlation with their body mass index (BMI). We found that high BMI was associated with an increased activation status of peripheral NK cells, as measured by surface levels of CD69 and levels of granzyme-B. However, these activated NK cells had an impaired capacity to degranulate or to produce cytokines/chemokines when exposed to tumor cell lines deficient in MHC-I expression or coated with antibodies. This suggests that chronic stimulation of NK cells during obesity may lead to their incapacity to respond normally and eliminate target cells, which could contribute to the greater susceptibility of obese individuals to develop cancers or infectious diseases.

TGF-ß inhibits the activation and functions of NK cells by repressing the mTOR pathway.

Transforming growth factor-ß (TGF-ß) is a major immunosuppressive cytokine that maintains immune homeostasis and prevents autoimmunity through its antiproliferative and anti-inflammatory properties in various immune cell types. We provide genetic, pharmacologic, and biochemical evidence that a critical target of TGF-ß signaling in mouse and human natural killer (NK) cells is the serine and threonine kinase mTOR (mammalian target of rapamycin). Treatment of mouse or human NK cells with TGF-ß in vitro blocked interleukin-15 (IL-15)-induced activation of mTOR. TGF-ß and the mTOR inhibitor rapamycin both reduced the metabolic activity and proliferation of NK cells and reduced the abundances of various NK cell receptors and the cytotoxic activity of NK cells. In vivo, constitutive TGF-ß signaling or depletion of mTOR arrested NK cell development, whereas deletion of the TGF-ß receptor subunit TGF-ßRII enhanced mTOR activity and the cytotoxic activity of the NK cells in response to IL-15. Suppression of TGF-ß signaling in NK cells did not affect either NK cell development or homeostasis; however, it enhanced the ability of NK cells to limit metastases in two different tumor models in mice. Together, these results suggest that the kinase mTOR is a crucial signaling integrator of pro- and anti-inflammatory cytokines in NK cells. Moreover, we propose that boosting the metabolic activity of antitumor lymphocytes could be an effective strategy to promote immune-mediated tumor suppression.

The basophil activation test: a sensitive test in the diagnosis of allergic immediate hypersensitivity to pristinamycin.

Immediate hypersensitivity (IHS) reactions to macrolides and to macrolide-derived antibiotics like pristinamycin are uncommon. In this context, there is little data available to appreciate the true value of biological tools regarding the diagnosis of immediate allergy to pristinamycin. Here we assess the clinical usefulness of the basophil activation test (BAT) to differentiate allergic from nonallergic IHS to pristinamycin. Thirty-six patients were tested with skin tests as the gold standard and BAT. The BAT achieved a sensitivity of 76% and a specificity of 100%, implying an absence of false positive results. Multicenter studies remain to be performed to better define the sensitivity, specificity and interlaboratory variation of BAT in the diagnosis of allergy to pristinamycin and macrolides.

PRKDC mutations associated with immunodeficiency, granuloma, and autoimmune regulator-dependent autoimmunity.

BACKGROUND: PRKDC encodes for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a kinase that forms part of a complex (DNA-dependent protein kinase [DNA-PK]) crucial for DNA double-strand break repair and V(D)J recombination. In mice DNA-PK also interacts with the transcription factor autoimmune regulator (AIRE) to promote central T-cell tolerance. OBJECTIVE: We sought to understand the causes of an inflammatory disease with granuloma and autoimmunity associated with decreasing T- and B-cell counts over time that had been diagnosed in 2 unrelated patients. METHODS: Genetic, molecular, and functional analyses were performed to characterize an inflammatory disease evocative of a combined immunodeficiency. RESULTS: We identified PRKDC mutations in both patients. These patients exhibited a defect in DNA double-strand break repair and V(D)J recombination. Whole-blood mRNA analysis revealed a strong interferon signature. On activation, memory T cells displayed a skewed cytokine response typical of TH2 and TH1 but not TH17. Moreover, mutated DNA-PKcs did not promote AIRE-dependent transcription of peripheral tissue antigens in vitro. The latter defect correlated in vivo with production of anti-calcium-sensing receptor autoantibodies, which are typically found in AIRE-deficient patients. In addition, 9 months after bone marrow transplantation, patient 1 had Hashimoto thyroiditis, suggesting that organ-specific autoimmunity might be linked to nonhematopoietic cells, such as AIRE-expressing thymic epithelial cells. CONCLUSION: Deficiency of DNA-PKcs, a key AIRE partner, can present as an inflammatory disease with organ-specific autoimmunity, suggesting a role for DNA-PKcs in regulating autoimmune responses and maintaining AIRE-dependent tolerance in human subjects.

Improving the cytological diagnosis of intraocular lymphoma from vitreous fluid.

AIMS: To improve the cytological diagnosis of retinal lymphoma on vitreous fluid using improved cell collection and systematic analyses. METHODS AND RESULTS: Since October 2010, we have developed and optimized in our department a method with which to perform the diagnosis of retinal lymphoma. The vitreous sample was collected in a tube containing RPMI-1640 medium, decomplemented fetal bovine serum, and gentamicin. The transport and technical steps were performed at 4°C. Systematically, cytological examination with May-Grünwald-Giemsa staining and immunocytochemistry (mainly anti-CD3, anti-CD20 and anti-CD68 antibodies) were performed on cytospins. Whenever possible, determination of B-cell clonality, flow cytometry and determination of the interleukin (IL)-10/IL-6 ratio were performed. From October 2010 to June 2013, with this optimized protocol, 38 vitreous cytological samples from 32 patients were analysed, and a final diagnosis was possible, avoiding a biopsy, in all cases except one. CONCLUSION: The preservation of vitreous fluid cells on culture medium led to the diagnosis of retinal lymphoma in 10 of 12 cases, and exclusion of this diagnosis in 26 cases. This protocol may be applied even when the delay in shipping from the surgery to the pathology departments exceeds 1 h.

Early diagnosis of celiac disease in IgA deficient children: contribution of a point-of-care test.

BACKGROUND: The serological diagnosis of celiac disease (CD) often relies on the presence of anti-tissue transglutaminase (tTG) IgA autoantibodies. Patients suffering from selective IgA deficiency (IgAD) are often not aware of their IgA deficiency and are tested as CD negative, delaying considerably the diagnosis. The detection of IgG against deamidated gliadin peptides (DGP) has high specificity and better sensitivity than IgG anti-tTG. A multi-analytic lateral-flow immunochromatographic assay (CD-LFIA) based on the detection of IgA and IgG anti-DGP and total IgA was shown to have a good diagnostic accuracy for CD. The aim of this study was to evaluate the clinical accuracy of its use in children suffering from IgAD. METHODS: 45 IgAD children ranging from 1.1 to 17.4 years and suspected of CD or having high CD risk factors were referred from outpatient clinics located in the area of Rhone-Alpes (France) to the Hospices Civils de Lyon, Paediatric Hospital-Gastroenterology-Hepatology- Nutrition Department for further CD investigations. The CD investigations, including the sample collection, were performed within the Paediatric Hospital-Gastroenterology-Hepatology- Nutrition Department, and the serological testing was performed at the Lyon-Sud Hospital-Immunology Laboratory. The diagnosis of CD was based on IgG anti-tTG serology, biopsy results and patient follow-up. The serum samples were retrospectively tested on the CD-LFIA test. RESULTS: A total of eight (8) patients were diagnosed as new CD. All were correctly identified by the CD-LFIA. The test yielded four (4) false positive results. Two patients with positive IgG anti-tTG were negative on CD-LFIA, but were classified as CD negative based on biopsy results and patient follow-up. The remaining 33 patients were found negative by both methods. The specificity and sensitivity of CD-LFIA was of 89.2% [74.6-97.0] and of 100% [63.1-100] respectively. The negative predictive value (NPV) was of 100% [89.4-100], and the Likelihood Ratio for Negative Test (LR-) was of 0 [0.0-0.91]. CONCLUSIONS: CD-LFIA is a useful, non-invasive and rapid tool to rule out CD in primary care paediatric patients having CD-related symptoms and IgAD. Patients having a positive CD-LFIA result could be then readily directed to secondary care setting for further evaluation by standard serology and biopsy.

The metabolic checkpoint kinase mTOR is essential for IL-15 signaling during the development and activation of NK cells.

Interleukin 15 (IL-15) controls both the homeostasis and the peripheral activation of natural killer (NK) cells. The molecular basis for this duality of action remains unknown. Here we found that the metabolic checkpoint kinase mTOR was activated and boosted bioenergetic metabolism after exposure of NK cells to high concentrations of IL-15, whereas low doses of IL-15 triggered only phosphorylation of the transcription factor STAT5. mTOR stimulated the growth and nutrient uptake of NK cells and positively fed back on the receptor for IL-15. This process was essential for sustaining NK cell proliferation during development and the acquisition of cytolytic potential during inflammation or viral infection. The mTORC1 inhibitor rapamycin inhibited NK cell cytotoxicity both in mice and humans; this probably contributes to the immunosuppressive activity of this drug in different clinical settings.

Comparison of anti-CCP autoantibodies measurement by ELISA and a bead-based assay in a large patient cohort.

OBJECTIVES: The aims of our study were to compare in a cohort of 705 patients the diagnostic performance of two tests to detect autoantibodies to cyclic citrullinated peptides (CCP) and to determine whether a bead-based assay within a multiplex flow immunoassay (MFA) can be used instead of an enzyme linked immunosorbent assay (ELISA) technique in routine practice. DESIGN AND METHODS: Six hundred and thirty patients with rheumatic symptoms and 75 patients with systemic lupus erythematosus (SLE) were tested for anti-CCP autoantibodies using two techniques: ELISA (Inova) and MFA (BioPlex, Bio-Rad). RESULTS: Using kappa coefficient, there was an excellent agreement between ELISA and MFA when comparing 630 patients with rheumatic symptoms (κ coefficient, 0.82). In this cohort 174 patients were identified as suffering from RA, while 456 patients suffered from other diseases. Sensitivity and specificity values of anti-CCP autoantibodies for RA were 70.7% and 92.3% for ELISA and 64.4% and 92.8% for MFA. The positive and negative predictive values were 77.4% and 89.2% for ELISA and 77.2% and 87.2% for MFA, respectively. There were no differences in the diagnostic performances between the two assays (Z=0.67). The specificity values of anti-CCP autoantibodies analysing patients with SLE were 97.3% with MFA and 96% with ELISA with an excellent agreement between the methods (98.7%; κ coefficient, 0.79). CONCLUSION: Concordance between ELISA and MFA is high in routine practice. Overall, MFA is a powerful tool for rapid assessment of anti-CCP autoantibodies and can replace the ELISA technique, which could be used as a second-line test in some cases.

T-bet and Eomes instruct the development of two distinct natural killer cell lineages in the liver and in the bone marrow.

Trail(+)DX5(-)Eomes(-) natural killer (NK) cells arise in the mouse fetal liver and persist in the adult liver. Their relationships with Trail(-)DX5(+) NK cells remain controversial. We generated a novel Eomes-GFP reporter murine model to address this question. We found that Eomes(-) NK cells are not precursors of classical Eomes(+) NK cells but rather constitute a distinct lineage of innate lymphoid cells. Eomes(-) NK cells are strictly dependent on both T-bet and IL-15, similarly to NKT cells. We observed that, in the liver, expression of T-bet in progenitors represses Eomes expression and the development of Eomes(+) NK cells. Reciprocally, the bone marrow (BM) microenvironment restricts T-bet expression in developing NK cells. Ectopic expression of T-bet forces the development of Eomes(-) NK cells, demonstrating that repression of T-bet is essential for the development of Eomes(+) NK cells. Gene profile analyses show that Eomes(-) NK cells share part of their transcriptional program with NKT cells, including genes involved in liver homing and NK cell receptors. Moreover, Eomes(-) NK cells produce a broad range of cytokines, including IL-2 and TNF in vitro and in vivo, during immune responses against vaccinia virus. Thus, mutually exclusive expression of T-bet and Eomes drives the development of different NK cell lineages with complementary functions.

Activation of Natural Killer Cells in Patients with Chronic Bone and Joint Infection due to Staphylococci Expressing or Not the Small Colony Variant Phenotype.

Chronic bone and joint infections (BJI) are devastating diseases. Relapses are frequently observed, as some pathogens, especially staphylococci, can persist intracellularly by expressing a particular phenotype called small colony variant (SCV). As natural killer (NK) cells are lymphocytes specialized in the killing of host cells infected by intracellular pathogens, we studied NK cells of patients with chronic BJI due to staphylococci expressing or not SCVs (10 patients in both groups). Controls were patients infected with other bacteria without detectable expression of SCVs, and healthy volunteers. NK cell phenotype was evaluated from PBMCs by flow cytometry. Degranulation capacity was evaluated after stimulation with K562 cells in vitro. We found that NK cells were activated in terms of CD69 expression, loss of CD16 and perforin, in all infected patients in comparison with healthy volunteers, independently of the SCV phenotype. Peripheral NK cells in patients with chronic BJI display signs of recent activation and degranulation in vivo in response to CD16-mediated signals, regardless of the type of bacteria involved. This could involve a universal capacity of isolates responsible for chronic BJI to produce undetectable SCVs in vivo, which might be a target of future intervention.

Monitoring NK cell activity in patients with hematological malignancies.

Natural killer (NK) cells are lymphocytes of the innate immune system that can recognize and kill various types of malignant cells. Monitoring the activity of peripheral NK cells in patients affected by hematological malignancies may provide prognostic information or unveil ongoing tumor-specific immune responses. Moreover, further insights into the biology of NK cells might also promote the development of novel strategies for stimulating their anticancer activity. Here, we review the main methods to monitor phenotypic and functional NK cell properties in cancer patients, focusing on individuals affected by multiple myeloma, a hematological malignancy currently treated with immunomodulatory drugs.

Intraperitoneal cytokine level in patients with peritoneal surface malignancies. A study of the RENAPE (French Network for Rare Peritoneal Malignancies).

BACKGROUND: Prognosis of peritoneal surface malignancies is influenced by the adequacy of surgical and chemotherapeutic treatment and by tumor spread at the time of diagnosis. By promoting morphological changes in the mesothelium, inflammatory cytokines reflect tumor biology and could be evaluated as biomarkers. Our objective was to evaluate intraperitoneal levels of IL-6, IL-8, IL-10, TNF-alpha, and sICAM in patients with pseudomyxoma peritonei and peritoneal mesothelioma. METHODS: Serum and peritoneal fluid samples were prospectively collected in patients managed for peritoneal surface malignancies including pseudomyxoma peritonei (PMP), mesotheliomas, and other rare primitive peritoneal cancers (cancer group) and patients who underwent intraperitoneal laparoscopic surgical procedures for benign diseases (noncancer group). Samples were analyzed for IL-6, IL-8, IL-10, TNF-alpha, and sICAM concentrations. Correlations were assessed with tumor spread related clinical scores. RESULTS: In both patient groups, intraperitoneal cytokine levels were higher than serum levels. Cancer patients had significantly higher intraperitoneal cytokine levels than noncancer patients. Peritoneal levels tended to increase in cancer patients with free tumor cells in peritoneal fluid. They were significantly higher in patients with tumor implants ≥2 cm and/or patients with peritoneal carcinomatosis index (PCI) >19. Furthermore, patients with malignant pseudomyxoma peritonei (grades II and III) had higher levels than patients with nonmalignant disease (grade I). CONCLUSIONS: Assessment of intraperitoneal IL-6, IL-8, IL-10, TNF-alpha, and sICAM levels can be performed in patients with peritoneal surface malignancies. They can be considered as both diagnostic and prognostic biomarkers that could be used as useful adjuncts for therapeutic decision making.

Differential dose effect of fish oil on inflammation and adipose tissue gene expression in chronic kidney disease patients.

OBJECTIVE: The beneficial effects of ω-3 polyunsaturated fatty acids (PUFAs) in cardiovascular disease are partly attributed to their anti-inflammatory properties. Their potential effect on the adipose tissue of chronic kidney disease (CKD) patients has never been explored. METHODS: To determine the metabolic effect of supplementation with two different doses of fish oil (FO), 12 non-dialyzed patients with stage IV/V CKD were randomly allocated to receive 1.8 g or 3.6 g/d of ω-3 PUFA for 10 wk. Metabolic parameters, adipose tissue function, and gene expression were evaluated at baseline and 10 wk. RESULTS: Body weight, fat mass, energy intake, fasting glucose, and insulin were unchanged. The daily intake of 3.6 g of ω-3 PUFA resulted in decreased serum triacylglycerol and increased high-density lipoprotein cholesterol, whereas low-density lipoprotein cholesterol increased with 1.8 g of ω-3 PUFA. Serum adiponectin, leptin, C-reactive protein, and tumor necrosis factor-α were not modified in either group. Interleukin-6 levels tended to decrease with 1.8 g of ω-3 PUFA. Additionally, a subset of inflammation-related genes (CD68 and MMP9) was reduced in subcutaneous adipose tissue in this group. Adiponectin, leptin, and adipoR2 gene expression were upregulated with 3.6 g of ω-3 PUFA. CONCLUSIONS: A moderate dose of FO alters the gene expression profile of adipose tissue to a more antiinflammatory status. Higher doses of FO have a favorable effect on lipid profile and lead to the upregulation of adipokines gene expression suggesting a different dose response to ω-3 PUFA administration in patients with CKD.

Profiling sirolimus-induced inflammatory syndrome: a prospective tricentric observational study.

BACKGROUND: The use of the immunosuppressant sirolimus in kidney transplantation has been made problematic by the frequent occurrence of various side effects, including paradoxical inflammatory manifestations, the pathophysiology of which has remained elusive. METHODS: 30 kidney transplant recipients that required a switch from calcineurin inhibitor to sirolimus-based immunosuppression, were prospectively followed for 3 months. Inflammatory symptoms were quantified by the patients using visual analogue scales and serum samples were collected before, 15, 30, and 90 days after the switch. RESULTS: 66% of patients reported at least 1 inflammatory symptom, cutaneo-mucosal manifestations being the most frequent. Inflammatory symptoms were characterized by their lability and stochastic nature, each patient exhibiting a unique clinical presentation. The biochemical profile was more uniform with a drop of hemoglobin and a concomitant rise of inflammatory acute phase proteins, which peaked in the serum 1 month after the switch. Analyzing the impact of sirolimus introduction on cytokine microenvironment, we observed an increase of IL6 and TNFα without compensation of the negative feedback loops dependent on IL10 and soluble TNF receptors. IL6 and TNFα changes correlated with the intensity of biochemical and clinical inflammatory manifestations in a linear regression model. CONCLUSIONS: Sirolimus triggers a destabilization of the inflammatory cytokine balance in transplanted patients that promotes a paradoxical inflammatory response with mild stochastic clinical symptoms in the weeks following drug introduction. This pathophysiologic mechanism unifies the various individual inflammatory side effects recurrently reported with sirolimus suggesting that they should be considered as a single syndromic entity.