Kristin A. Erickson

Naturally occurring tolerance acquisition to foods in previously allergic children is characterized by antigen specificity and associated with increased subsets of regulatory T cells.

Food allergy affects approximately 6–8% of children, and increasing in prevalence. Some children naturally outgrow their food allergy without intervention, but the mechanisms by which this occurs remain poorly understood. We sought to investigate the role of regulatory T cells in the development of naturally acquired tolerance.

Cytokine responses to egg protein in previously allergic children who developed tolerance naturally

Egg allergy is the second most common food allergy in childhood, characteristics are listed in eTable 1, available online). Patients with with 1% to 2% of Americans affected.1,2 Although approximately 70% of children outgrow this allergy,3 few studies have explored the mechanism by which children naturally outgrow the allergy (natural tolerance [NT]). Most studies have compared children with allergy with those who were never allergic, have not evaluated allergen-specific responses, or have only focused on treatment inducing desensitization (oral immunotherapy). Although not previously demonstrated in food allergy, tolerance to venom has been associated with elevation of interleukin (IL)-10.4 Our hypothesis was that peripheral blood mononuclear cells (PBMCs) stimulated with ovalbumin (OVA) in NT has increased allergenspecific IL-10 production. The objective was to determine the PBMC cytokine response to egg protein in previously allergic patients who developed NT and thus differentiate them from children with allergy. Food allergy was defined by an allergist-immunologist as a history of IgE-mediated reaction to egg (anaphylaxis, urticaria, or significant vomiting) within 2 hours of food ingestion and positive laboratory testing (skin prick mean wheal diameter 4 mm larger than saline wheal and/or specific IgE [sIgE] level 2 kU/L). Nonallergic (control) was defined as no history of clinical reactivity to egg. NT was defined as a clinical and laboratory history of egg allergy but passing an open food challenge to 1 scrambled egg within 6 months of recruitment. The PBMCs were stimulated with or without OVA or with anti-CD3 and anti-CD28. After 48 hours, the supernatant was collected and cytokines were analyzed using multiplex assays (eMethods). Patient characteristics, fold stimulation, and sIgE/sIgG4 ratio were compared using the Mann-Whitney or Kruskal-Wallis test. Cytokine data were logarithmically transformed, dose-dependent responses were analyzed with repeated-measures analysis of variance (ANOVA), and comparisons at specific doses were performed with ANOVA or t test. Data analysis was performed using SAS 9.3 (SAS Institute, Cary, North Carolina) and SPSS 14 (SPSS, Inc, Chicago, Illinois), with a 2-sided type I error rate of 5%. Forty children (11 with NT, 20 with allergy, and 9 without allergy; median age 6 years, range 2e18 years) were recruited from a cross-sectional, caseecontrol convenience sample (patient

Fetal cord blood and tissue immune responses to chronic placental inflammation and chorioamnionitis

BackgroundChorioamnionitis is a risk factor for future asthma development. Animal models of chorioamnionitis demonstrate increased TH17-to-Treg ratios associated with proinflammatory cytokine elevations. The association of chorioamnionitis on human neonatal immune cells systemically and within tissues is not known.MethodsWe enrolled two cohorts to evaluate TH17 and regulatory T cell (Treg) phenotypic markers in chorioamnionitis. From a cohort of 19 live birth infants, we collected cord blood and placenta samples to evaluate for signs of acute and chronic histologic inflammation and cell phenotype characterization. We analyzed a second cohort of stillborn infants with and without chorioamnionitis to classify and enumerate cell infiltrate phenotypes in the spleen, thymus, and lung. We used linear regression analysis determine the association of retinoic acid-related orphan receptor gamma t positive (RORγt+) and Treg cell frequency with different types of inflammation seen in the live cohort subjects. Using linear mixed models, we evaluated for any associations between chorioamnionitis and T- and B-cell with a logarithmic scale for level of expression of cellular markers. We then performed Wilcoxon rank sum tests to assess the associations between cell count and chorioamnionitis.ResultsIn the live birth subjects with chronic placental inflammation we observed an increased proportion of RORγt+ cells in Foxp3+ cells, regardless of the presence of acute inflammation, compared to subjects with neither acute nor chronic inflammation. We also found an increased proportion of RORγt+ cells within Foxp3+ cells in subjects with acute high stage fetal and maternal inflammation compared to those without acute or chronic inflammation. In the stillborn subjects with chorioamnionitis, we observed a decrease in splenic Foxp3+ cells and an increase in lung CD3+ cells compared with subjects that did not have chorioamnionitis.ConclusionExposure to chorioamnionitis in utero may affect immune activation in neonates with an increased frequency of RORγt+ cells systemically as well as lymphocytic infiltrate in the lung. Our findings suggest an increase in RORγt+ cells during chorioamnionitis and thus may support the known associations between chorioamnionitis with asthma.