T-cell Receptor Excision Circles Levels Research Articles

Immunologic Heterogeneity in 2 Cartilage-Hair Hypoplasia Patients With a Distinct Clinical Course.

Cartilage-hair hypoplasia (CHH) syndrome is a rare autosomal recessive syndrome associated with skeletal dysplasia, varying degrees of combined immunodeficiency (CID), short stature, hair hypoplasia, macrocytic anemia, increased risk of malignancies, and Hirschsprung disease. To provide clinical and immunological insights obtained from 2 unrelated patients who displayed clinical characteristics of CHH. Two patients with suspected CHH syndrome due to skeletal dysplasia and immunodeficiency underwent an immunological and genetic work-up using flow cytometry, next-generation sequencing (NGS) of the immune repertoire, and Sanger sequencing to identify the underlying defects. Patient 1 presented with low birth weight and skeletal dysplasia. Newborn screening was suggestive of T-cell immunodeficiency, as T-cell receptor excision circle levels were undetectable. Both the T-cell receptor (TCR) Vß and TCR-g (TRG) repertoires were restricted, with evidence of clonal expansion. Genetic analysis identified compound heterozygous RMRP variants inherited from both parents. Patient 2 presented with recurrent lung and gastrointestinal infections, skeletal dysplasia, failure to thrive, and hepatomegaly. The polyclonal pattern of the TCRß repertoire was normal, with only slight overexpression of TCR-ßV20 and restricted expression of Vßs. TRG expressed a normal diverse repertoire, similar to that of the healthy control sample. Genetic analysis identified biallelic novel regulatory variants in RMRP. Both parents are carriers of this mutation. Our findings demonstrate how the immunological work-up, supported by genetic findings, can dramatically change treatment and future outcome in patients with the same clinical syndrome.

Severe congenital T-lymphocytopenia may affect the outcome of neonatal intensive care.

Circular DNA segments TREC (T-cell receptor excision circles) formed during T-lymphocyte maturation in the thymus, are a sensitive marker of thymic lymphocyte production in a broader manner. Quantification using qPCR is proposed as a surrogate marker of T cell malfunction in various primary and secondary conditions in a non-SCID selected risk newborn population. We collected 207 dry blood spot samples during the years 2015-2018, from newly admitted risk newborns. TREC values calculated per 106 cells were determined and a cut-off values of 5th percentile was set. The positive control group consisted of patients (n=13) with genetically confirmed SCID. The median TREC value was 34,591.56 (18,074.08-60,228.58) for girls resp. 28,391.20 (13,835.01-51,835.93) per 106 cells for boys, P=0.046. Neonates born by C-section have been found to have higher TREC levels compared to neonates born by spontaneous delivery (P=0.018). In the group of preterm newborns (n=104), 3.8% had TREC value < 5th percentile, half of them died due to sepsis as opposed to no fatalities in preterm newborns with sepsis and TREC value > 5th percentile. In the group of term newborns (n=103) 9 children (8.7%) had TREC < 5th percentile, half of them were treated for asphyxia, with no fatal complications. TREC levels calculated for the 5th percentile of a risk neonatal group is suggested as a surrogate marker for increased risk of fatal septic complication. Early recognition of these newborns within a risk scoring system using TREC levels could lead to potentially lifesaving interventions.

Normal neonatal TREC and KREC levels in early onset juvenile idiopathic arthritis

Dysregulated central tolerance predisposes to autoimmune diseases. Reduced thymic output as well as compromised central B cell tolerance checkpoints have been proposed in the pathogenesis of juvenile idiopathic arthritis (JIA). The aim of this study was to investigate neonatal levels of T-cell receptor excision circles (TRECs) and kappa-deleting element excision circles (KRECs), as markers of T- and B-cell output at birth, in patients with early onset JIA. TRECs and KRECs were quantitated by multiplex qPCR from dried blood spots (DBS), collected 2-5days after birth, in 156 children with early onset JIA and in 312 matched controls. When analysed from neonatal dried blood spots, the median TREC level was 78 (IQR 55-113) in JIA cases and 88 (IQR 57-117) copies/well in controls. The median KREC level was 51 (IQR 35-69) and 53 (IQR 35-74) copies/well, in JIA cases and controls, respectively. Stratification by sex and age at disease onset did not reveal any difference in the levels of TRECs and KRECs. T- and B-cell output at birth, as measured by TREC and KREC levels in neonatal dried blood spots, does not differ in children with early onset JIA compared to controls.

Positive Newborn Screening for Severe Combined Immunodeficiency: What Should the Pediatrician Do?

Severe combined immunodeficiency (SCID) is a group of diseases characterized by low T-cell count and impaired T-cell function, resulting in severe cellular and humoral immune defects. If not diagnosed and treated promptly, infants affected by this condition can develop severe infections which will result in death. Delayed treatment can markedly reduce the survival outcome of infants with SCID. T-cell receptor excision circle (TREC) levels are measured on newborn screening to promptly identify infants with SCID. It is important for primary care providers and pediatricians to understand the approach to managing infants with positive TREC-based newborn screening as they may be the first contact for infants with SCID. Primary care providers should be familiar with providing anticipatory guidance to the family in regard to protective isolation, measures to minimize the risk of infection, and the coordination of care with the SCID coordinating center team of specialists. In this article, we use case-based scenarios to review the principles of TREC-based newborn screening, the genetics and subtypes of SCID, and management for an infant with a positive TREC-based newborn screen.

Blood levels of T-Cell Receptor Excision Circles (TRECs) provide an index of exposure to traumatic stress in mice and humans

Exposure to stress triggers biological changes throughout the body. Accumulating evidence indicates that alterations in immune system function are associated with the development of stress-associated illnesses such as major depressive disorder and post-traumatic stress disorder, increasing interest in identifying immune markers that provide insight into mental health. Recombination events during T-cell receptor rearrangement and T-cell maturation in the thymus produce circular DNA fragments called T-cell receptor excision circles (TRECs) that can be utilized as indicators of thymic function and numbers of newly emigrating T-cells. Given data suggesting that stress affects thymus function, we examined whether blood levels of TRECs might serve as a quantitative peripheral index of cumulative stress exposure and its physiological correlates. We hypothesized that chronic stress exposure would compromise thymus function and produce corresponding decreases in levels of TRECs. In male mice, exposure to chronic social defeat stress (CSDS) produced thymic involution, adrenal hypertrophy, and decreased levels of TRECs in blood. Extending these studies to humans revealed robust inverse correlations between levels of circulating TRECs and childhood emotional and physical abuse. Cell-type specific analyses also revealed associations between TREC levels and blood cell composition, as well as cell-type specific methylation changes in CD4T + and CD8T + cells. Additionally, TREC levels correlated with epigenetic age acceleration, a common biomarker of stress exposure. Our findings demonstrate alignment between findings in mice and humans and suggest that blood-borne TRECs are a translationally-relevant biomarker that correlates with, and provides insight into, the cumulative physiological and immune-related impacts of stress exposure in mammals.

T cell receptor excision circles are potential predictors of survival in adult allogeneic hematopoietic stem cell transplantation recipients with acute myeloid leukemia.

BackgroundLymphocyte neogenesis from primary lymphoid organs is essential for a successful reconstitution of immunity after allogeneic hematopoietic stem cell transplantation (HSCT). This single-center retrospective study aimed to evaluate T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) as surrogate markers for T and B cell recovery, as predictors for transplantation-related outcomes in adult acute myeloid leukemia (AML) patients.MethodsNinety adult patients diagnosed with AML and treated with HSCT between 2010 and 2015 were included in the study. TREC and KREC levels were measured by quantitative PCR at 1, 3, 6, and 12 months after transplantation.ResultsOverall, excision circle levels increased between 3 and 6 months post-HSCT for TREC (p = 0.005) and 1 and 3 months for KREC (p = 0.0007). In a landmark survival analysis at 12 months post-HSCT, TREC levels were associated with superior overall survival (HR: 0.52, 95% CI: 0.34 - 0.81, p = 0.004). The incidence of viral infections within the first 100 days after transplantation was associated with lower TREC levels at 6 months (p = 0.0002). CMV reactivation was likewise associated with lower TREC levels at 6 months (p = 0.02) post-HSCT. KREC levels were not associated with clinical outcomes in statistical analyzes.ConclusionsResults from the present study indicate that TREC measurement could be considered as part of the post-HSCT monitoring to identify AML patients with inferior survival after transplantation. Further prospective studies are warranted to validate these findings.

Abstract 2003: Poor diet quality is associated with immune aging in survivors of pediatric acute lymphoblastic leukemia

Abstract Rationale and objectives: Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. Despite a 90% five-year survival rate, survivors of childhood ALL often suffer from late effects, including cardiometabolic disorders. Contributing factors such as inflammation and oxidative stress, combined with drug treatments, can induce premature aging and cellular senescence with a significant impact on cardiometabolic disorders. Premature aging can lead to decreased thymic T-cell production, resulting in decreased circulation of T-cell receptor excision circles (TRECs). Because diet has been associated with cardiometabolic disorders, we hypothesized that the quality of diet in children who had survived ALL was related to the immune aging biomarker TREC, in concert with inflammatory status. Methods: Adolescent and young adult survivors of pediatric ALL of the PETALE cohort (n=241, 22.1 ± 6.3 years at diagnosis, 49.4% male) were examined in their profile for TREC levels (by qPCR) and for adherence to 6 diet quality indices. Results: Adjusted linear regressions revealed that the Healthy Diet Indicator (HDI) was associated with TREC levels (β=50.0, p=0.005, adjusted p=0.03). After performing a conceptual relational analysis (CAR) for data mining of various biomarkers of inflammation, oxidative stress, endotoxemia, and endothelial or adipose dysfunction; interleukin-6 (IL-6) and C-reactive protein (CRP) were found to be negatively associated with TREC levels (β= -80 and -80.1, p=0.017 and 0.026, respectively) but not with HDI. Further analysis revealed that IL-6 and CRP levels were moderators, but not mediators, of the association between HDI and TREC. Conclusion: This study supports the positive impact of a healthy diet on premature immune aging and the moderating role of inflammation in this association. Citation Format: Abderrahim Benmoussa, Tibila Kientega, Sophia Morel, Guillaume Cardin, Sophie Bérard, Mickael wajnberg, Petko Valtchev, Alexandre Blondin-Masse, Daniel Curnier, Maja Krajinovic, Caroline Laverdière, Daniel Sinnett, Emile Levy, Sophie Marcoux, Francis Rodier, Valérie Marcil. Poor diet quality is associated with immune aging in survivors of pediatric acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2003.

TREC/KREC Levels and T and B Lymphocyte Subpopulations in COVID-19 Patients at Different Stages of the Disease.

Background: T and B cell-mediated immunity can be assessed using T cell receptor excision circle (TREC) and Kappa-deleting recombination excision circle (KREC) analysis, respectively, and successful implementation of this method requires evaluation of the correlation between the TREC frequencies and T cell subsets as well as KREC levels and B lymphocyte subsets. The aim of the present study was to evaluate the correlation between the TREC/KREC concentrations and T/B lymphocyte subsets at different stages of COVID-19. Methods: We examined 33 patients in the acute stage of COVID-19 (including 8 patients with poor outcomes) and 33 COVID-19 survivors. TREC/KREC concentrations were measured using quantitative real-time PCR. T/B lymphocyte subsets were determined using flow cytometry. Results: Blood TREC and KREC levels were found to be significantly lower in the acute stage of COVID-19 compared to control values. Moreover, a zero blood TREC level was a predictor of a poor disease outcome. Reductions in CD3+CD4+CD45RO−CD62L− and CD3+CD8+CD45RO−CD62L− T cell counts (as well as in the main fractions of B1 and B2 B cells) indicated a favorable outcome in COVID-19 patients in the acute stage of the disease. Decreased CD3+CD4+CD45RO−CD62L+ and CD3+CD8+CD45RO−CD62L+ T cell frequencies and increased CD3+CD8+CD45RO−CD62L− cell counts were found to indicate a poor outcome in patients with acute COVID-19. These patients were also found to have increased B1 cell counts while demonstrating no changes in B2 cell counts. The levels of effector T cell subsets an naïve B cells were normal in COVID-19 survivors. The most pronounced correlations between TREC/KREC levels and T/B cell subsets counts were observed in COVID-19 survivors: there were positive correlations with naïve T and B lymphocytes and negative correlations with central and effector memory T cell subsets. Conclusions: The assessment of correlations between TREC and T cell subsets as well as KREC levels and B cell subset counts in patients with acute COVID-19 and COVID-19 survivors has shown that blood concentrations of TREC and KREC are sensitive indicators of the stage of antigen-independent differentiation of adaptive immunity cells. The results of the TREC and KREC analysis correlated with the stages of COVID-19 and differed depending on the outcome of COVID-19.

Long-Term Follow-Up of Newborns with 22q11 Deletion Syndrome and Low TRECs

BackgroundPopulation-based neonatal screening using T-cell receptor excision circles (TRECs) identifies infants with profound T lymphopenia, as seen in cases of severe combined immunodeficiency, and in a subgroup of infants with 22q11 deletion syndrome (22q11DS).PurposeTo investigate the long-term prognostic value of low levels of TRECs in newborns with 22q11DS.MethodsSubjects with 22q11DS and low TRECs at birth (22q11Low, N=10), matched subjects with 22q11DS and normal TRECs (22q11Normal, N=10), and matched healthy controls (HC, N=10) were identified. At follow-up (median age 16 years), clinical and immunological characterizations, covering lymphocyte subsets, immunoglobulins, TRECs, T-cell receptor repertoires, and relative telomere length (RTL) measurements were performed.ResultsAt follow-up, the 22q11Low group had lower numbers of naïve T-helper cells, naïve T-regulatory cells, naïve cytotoxic T cells, and persistently lower TRECs compared to healthy controls. Receptor repertoires showed skewed V-gene usage for naïve T-helper cells, whereas for naïve cytotoxic T cells, shorter RTL and a trend towards higher clonality were found. Multivariate discriminant analysis revealed a clear distinction between the three groups and a skewing towards Th17 differentiation of T-helper cells, particularly in the 22q11Low individuals. Perturbations of B-cell subsets were found in both the 22q11Low and 22q11Normal group compared to the HC group, with larger proportions of naïve B cells and lower levels of memory B cells, including switched memory B cells.ConclusionsThis long-term follow-up study shows that 22q11Low individuals have persistent immunologic aberrations and increased risk for immune dysregulation, indicating the necessity of lifelong monitoring.Clinical ImplicationsThis study elucidates the natural history of childhood immune function in newborns with 22q11DS and low TRECs, which may facilitate the development of programs for long-term monitoring and therapeutic choices.

Кожные проявления первичных иммунодефицитных состояний

Primary immune deficiency diseases (PIDDs) are a group of severe genetically determined diseases caused by a disorder of the immunity links: humoral and cell-mediated links, phagocytosis, complement system. PIDDs are characterized by severe atypical recurrent infections, as well as autoimmune and oncological processes. In the case of clinical symptoms, skin manifestations in PIDDs allow to suspect the presence of congenital disorders of immunity. There is a technique in laboratory diagnostics of PIDDs, that determines a decrease in the number of T- and B-lymphocytes based on measuring the levels of TREC (T-cell Receptor Excision Circle) and KREC (Kappa-deleting Recombination Excision Circle), which are by-products of recombination of T- and B-cell receptor genes. TREC and KREC levels can be assessed using a reagent kit for quantifying TREC and KREC DNA by PCR in real time. The analysis can be conducted using both whole blood and DNA obtained from dried blood stains collected during the national newborn screening program. Today, quantitative analysis of TREC and KREC in dried blood stains on newborn screening cards is becoming the method of choice for newborn screening of PIDDs. The inclusion of the PIDDs diagnosis in the federal newborn screening program will allow detecting disorders of the immune system before their clinical manifestations, which will allow to apply modern treatment protocols, reduce disability and ensure high patient survival. KEYWORDS: TREC, KREC, PIDDs, newborn screening, PCR, immunity, early diagnosis. FOR CITATION: Churyukina E.V., Kudlay D.A. Skin manifestations of primary immune deficiency diseases. Russian Medical Inquiry. 2022;6(2):98–104 (in Russ.). DOI: 10.32364/2587-6821-2022-6-2-98-104

Ten Years of Newborn Screening for Severe Combined Immunodeficiency (SCID) in Massachusetts

To examine the outcomes of population newborn screening (NBS) for severe combined immunodeficiency (SCID) by using T-cell receptor excision circles (TRECs) after the first decade of implementation in Massachusetts.Infants born in Massachusetts screened through the New England Newborn Screening Program between February 1, 2009, and January 31, 2019.The authors present a population cohort of infants receiving NBS for SCID, both before and after mandatory NBS implementation in 2016.Of 720 038 infants screened, normal TRECs were identified in 99.71%. At least 1 abnormal specimen was identified in 2072 infants (0.29% of those screened). Of these infants, 1771 had an additional TREC result, which was normal, and were released from the screening program (83.8% of those with an abnormal TREC result before confirmatory flow cytometry and 1.7% after further lymphocyte phenotyping). Further evaluation by flow cytometry occurred in 237 infants (11.4% of those with at least 1 abnormal TREC result), and low naïve T-cell percentages were associated with a greater risk of a combined immunodeficiency. A total of 9 infants were diagnosed with SCID or leaky SCID, 7 were diagnosed with other combined immunodeficiencies, and 3 were diagnosed with athymia (0.4%, 0.3%, and 0.1%, respectively. of those with an abnormal TREC screen). The incidence of SCID or leaky SCID was reported as ∼1 in 80 000; however, more broadly, the incidence of severe T-cell lymphopenia for which definitive treatment was indicated was ∼1 in 50 000 infants. All patients with SCID or leaky SCID underwent hematopoietic cell transplant or gene therapy for which survival was 100%, and 1 patient with athymia underwent a successful thymus transplant. With NBS, the researchers successfully identified all known cases of SCID. Compared with survival before NBS by TREC, survival improved significantly for infants with SCID or leaky SCID (100% [n = 9] vs 57% [n = 7]. Of 162 infants with T-cell counts <2500 but above 1500 µL, no cases of SCID were identified, but 8 infants were diagnosed with partial DiGeorge syndrome.NBS of TREC levels is highly sensitive and specific, with the ability to improve early diagnosis of SCID. When compared with historical rates of SCID diagnosis and management before TREC evaluation by NBS, screening can reduce the time to transplant (3.4 months versus 6.5 months) and improve outcomes for infants with SCID.Screening for SCID has been a significant addition to NBS programs across the country, and multiple studies have suggested this to be a cost-effective strategy. As of December 2018, all 50 states have begun to screen for SCID at birth. SCID is often unrecognized in early life, but survival improves with early diagnosis. With this study, the authors provide long-term outcomes and highlight the benefit of these programs, suggesting a 43% reduction in mortality from a condition that can be successfully treated when identified early. From these data, the sensitivity, specificity, negative predictive value, and positive predictive value can be calculated (100%, 99.7%, 100%, and 0.91%, respectively). Notably, despite high sensitivity and specificity, a population prevalence of ∼1:50 000 to 80 000 lowers the positive predictive value of screening. Although early referral to an immunologist is important in infants with abnormal TREC results, these data also suggest the absolute risk of SCID in these infants is low (<1%). Thus, when counseling families of infants with an abnormal TREC screen, there is room for cautious optimism, pending results of definitive testing. More work is needed to better understand the short- and longer-term psychosocial impacts of a false-positive NBS result for SCID on families with unaffected infants after a positive screening test result.

Diagnosis of immunodeficiency conditions. Overview of the training event. Speakers I.N. Zakharova, I.A. Korsunsky

Primary immunodeficiencies (PIDs) are a heterogeneous group of genetic diseases. When PID is suspected, first of all, it is necessary to carefully collect the anamnesis, identify the features of clinical symptoms and the course of diseases in the child. To confirm the diagnosis, laboratory and instrumental methods of examination, immunological examination, and molecular genetic analysis are evaluated. As part of the immunological examination, as a screening method for detecting abnormalities in the T and B-cell parts of the immune system, a technique can be used to measure TREC (T-cell Receptor Excision Circle) and KREC (Kappa-deleting Recombination Excision Circle) levels by-products of T and B-cell receptor formation. A decrease in the amount of TREC and/or KREC in the blood indicates the presence of cellular PID. The assay can be performed using both whole blood and dried blood spots in children and adults.

First Year of TREC-Based National SCID Screening in Sweden.

Screening for severe combined immunodeficiency (SCID) was introduced into the Swedish newborn screening program in August 2019 and here we report the results of the first year. T cell receptor excision circles (TRECs), kappa-deleting element excision circles (KRECs), and actin beta (ACTB) levels were quantitated by multiplex qPCR from dried blood spots (DBS) of 115,786 newborns and children up to two years of age, as an approximation of the number of recently formed T and B cells and sample quality, respectively. Based on low TREC levels, 73 children were referred for clinical assessment which led to the diagnosis of T cell lymphopenia in 21 children. Of these, three were diagnosed with SCID. The screening performance for SCID as the outcome was sensitivity 100%, specificity 99.94%, positive predictive value (PPV) 4.11%, and negative predictive value (NPV) 100%. For the outcome T cell lymphopenia, PPV was 28.77%, and specificity was 99.95%. Based on the first year of screening, the incidence of SCID in the Swedish population was estimated to be 1:38,500 newborns.

Trends in TREC values according to age and gender in Chinese children and their clinical applications.

T cell receptor excision circles (TRECs) are small circularized DNA elements produced during rearrangement of T cell receptor (TCR) genes. Because TRECs are fairly stable, do not replicate during mitosis, and are not diluted during division of naïve T cells (Dion et al. [1]), they are suitable for assessing the number of newly formed T cells (Ping and Denise [2]). In this study, we detected TRECs in 521 healthy Chinese children aged 0-18years in different clinical settings. The TRECs decrease with aging and show lower levels in preterm and low birth weight (BW) babies compared to those in full-term infants, while the preterm babies can also show comparable levels of TRECs when they have a gestation age (GA)-matched BW. We found a strong correlation between TRECs and peripheral CD4 naïve T cell numbers, which was age-related. We also analyzed the TRECs in different PIDs. Since T cell defects vary in PIDs, TREC levels change inconsistently. For example, in Wiskott-Aldrich syndrome (WAS), combining the level of TREC with lymphocyte subsets can help to distinguish subtypes of disease.Conclusion: We established the reference value range for TRECs by evaluating children below 18years old in China, which could be used to screen for PIDs during early life. What is Known: • The TREC levels are decreased with age, and there is a positive correlation between TRECs and the numbers of naïve T cells. What is New: • This is the largest study to determine TREC reference levels in healthy Chinese pediatric, we provide solid data showing a correlation between CD4 naïve T cell counts and TREC levels according to age. We point out the GA matched BW is need to be considered during the SCID newborn screening. We are the first group showed that TREC levels can help clinician distinguish different WAS phenotype.

Second Tier Testing to Reduce the Number of Non-actionable Secondary Findings and False-Positive Referrals in Newborn Screening for Severe Combined Immunodeficiency

PurposeNewborn screening (NBS) for severe combined immunodeficiency (SCID) is based on the detection of T-cell receptor excision circles (TRECs). TRECs are a sensitive biomarker for T-cell lymphopenia, but not specific for SCID. This creates a palette of secondary findings associated with low T-cells that require follow-up and treatment or are non-actionable. The high rate of (non-actionable) secondary findings and false-positive referrals raises questions about the harm-benefit-ratio of SCID screening, as referrals are associated with high emotional impact and anxiety for parents.MethodsAn alternative quantitative TREC PCR with different primers was performed on NBS cards of referred newborns (N = 56) and epigenetic immune cell counting was used as for relative quantification of CD3 + T-cells (N = 59). Retrospective data was used to determine the reduction in referrals with a lower TREC cutoff value or an adjusted screening algorithm.ResultsWhen analyzed with a second PCR with different primers, 45% of the referrals (25/56) had TREC levels above cutoff, including four false-positive cases in which two SNPs were identified. With epigenetic qPCR, 41% (24/59) of the referrals were within the range of the relative CD3 + T-cell counts of the healthy controls. Lowering the TREC cutoff value or adjusting the screening algorithm led to lower referral rates but did not prevent all false-positive referrals.ConclusionsSecond tier tests and adjustments of cutoff values or screening algorithms all have the potential to reduce the number of non-actionable secondary findings in NBS for SCID, although second tier tests are more effective in preventing false-positive referrals.

TREC Screening for WHIM Syndrome.

T cell receptor excision circle (TREC) quantification is a recent addition to newborn screening (NBS) programs and is intended to identify infants with severe combined immunodeficiencies (SCID). However, other primary immunodeficiency diseases (PID) have also been identified as the result of TREC screening. We recently reported a newborn with a low TREC level on day 1 of life who was diagnosed with WHIM (warts, hypogammaglobulinemia, infections, myelokathexis) syndrome, a non-SCID primary immunodeficiency caused by mutations in the chemokine receptor CXCR4. We have now retrospectively reviewed the birth and clinical histories of all known WHIM infants born after the implementation of NBS for SCID. We identified six infants with confirmed WHIM syndrome who also had TREC quantification on NBS.Three of the six WHIM infants had low TREC levels on NBS. All sixpatients were lymphopenic but only one infant had a T cell count below 1,500 cells/μL. The most commonclinical manifestation was viral bronchiolitis requiring hospitalization. One infant died of complications related toTetralogy of Fallot, a known WHIM phenotype. The results suggest that WHIM syndrome should be considered in the differential diagnosis of newborns with low NBS TREC levels. Not applicable.

Characterization of Infants with Idiopathic Transient and Persistent T Cell Lymphopenia Identified by Newborn Screening-a Single-Center Experience in New York State.

Newborn screening (NBS) quantifies T cell receptor excision circles (TREC) and identifies infants with T cell lymphopenia (TCL). This study elucidates the demographics, laboratory characteristics, genetics, and clinical outcomes following live viral vaccine administration of term infants with transient or persistent idiopathic TCL. A single-center retrospective analysis was performed from September 2010 through June 2018. Laboratory variables were compared with Mann-Whitney tests. Correlations between initial TREC levels and T cell counts were determined by Spearman tests. Twenty-two transient and 21 persistent TCL infants were identified. Males comprised 68% of the transient and 52% of the persistent TCL cohorts. Whites comprised 23% of the transient and 29% of the persistent cohorts. Median initial TREC levels did not differ (66 vs. 60 TRECs/μL of blood, P = 0.58). The transient cohort had higher median initial CD3+ (2135 vs. 1169 cells/μL, P < 0.001), CD4+ (1460 vs. 866 cells/μL, P < 0.001), and CD8+ (538 vs. 277 cells/μL, P < 0.001) counts. The median age of resolution for the transient cohort was 38days. Genetic testing revealed 2 genes of interest which warrant further study and several variants of uncertain significance in immunology-related genes in the persistent cohort. 19 transient and 14 persistent subjects received the initial rotavirus and/or MMRV immunization. No adverse reactions to live viral vaccines were reported in either cohort. Transient and persistent TCL infants differ by demographic, laboratory, and clinical characteristics. Select transient and persistent TCL patients may safely receive live attenuated viral vaccines, but larger confirmatory studies are needed.

Dynamic of plasma IL-22 level is an indicator of thymic output after allogeneic hematopoietic cell transplantation

AimsInterleukin-22 (IL-22) promotes thymus recovery and improves T-cell recovery in preclinical allogeneic hematopoietic cell transplant models. However, the correlation between IL-22 and thymus recovery is unknown in human transplant. Materials and methodsIn this study, plasma IL-22 levels of transplanted humans were analyzed peri-transplant. Thymic output was assessed by detecting blood signal joint T-cell receptor excision circles (TRECs). Flow cytometry was applied to measure T-cell subsets. Key findingsPlasma IL-22 level positively correlated with blood TRECs level at days 14 and 28 posttransplant. Multiple linear regression analysis showed plasma IL-22 level, occurrence of acute graft-versus-host disease (aGVHD) and age were significantly associated with blood TRECs level at day 28 after allotransplant. An increase of plasma IL-22 level during day 14 and day 28 correlated with faster recovery of blood TRECs and naïve T-cell levels in allotransplant recipients. Recipients with high TRECs levels at day 28 had lower incidence of aGVHD comparing with those who with low TRECs levels according to a median split of their TRECs levels, an effect also seen in the high IL-22 level and low IL-22 level cohorts. Other factors such as age and infection had impacts on plasma IL-22 level in allotransplants. SignificanceOur findings suggest that dynamic change of plasma IL-22 level is an indicator of thymic output and occurrence of aGVHD. Monitoring plasma IL-22 level might help to assess recovery of thymus function in human allotransplants.

T-Cell Receptor Excision Circles in Newborns With Congenital Heart Disease

BT Davey, RW Elder, MM Cloutier. J Pediatr. 2019;213:96–102.e2 The authors of this study sought to inform their hypothesis that patients with congenital heart disease (CHD) had lower T-cell receptor excision circles (TRECs) than the general population, and low TREC levels in CHD patients are associated with infections leading to hospitalization. Five hundred and seventy-five patients with a diagnosis of structural CHD born between October 2011 and April 2016 were enrolled in this study. They were recruited from the two major Connecticut children’s hospitals, Connecticut Children’s Medical Center and Yale-New Haven Children’s Hospital, which …

Establishing Simultaneous T Cell Receptor Excision Circles (TREC) and K-Deleting Recombination Excision Circles (KREC) Quantification Assays and Laboratory Reference Intervals in Healthy Individuals of Different Age Groups in Hong Kong.

The clinical experience gathered throughout the years has raised awareness of primary immunodeficiency diseases (PIDD). T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) assays for thymic and bone marrow outputs measurement have been widely implemented in newborn screening (NBS) programs for Severe Combined Immunodeficiency. The potential applications of combined TREC and KREC assay in PIDD diagnosis and immune reconstitution monitoring in non-neonatal patients have been suggested. Given that ethnicity, gender, and age can contribute to variations in immunity, defining the reference intervals of TREC and KREC levels in the local population is crucial for setting up cut-offs for PIDD diagnosis. In this retrospective study, 479 healthy Chinese sibling donors (240 males and 239 females; age range: 1 month−74 years) from Hong Kong were tested for TREC and KREC levels using a simultaneous quantitative real-time PCR assay. Age-specific 5th–95th percentile reference intervals of TREC and KREC levels (expressed in copies per μL blood and copies per 106 cells) were established in both pediatric and adult age groups. Significant inverse correlations between age and both TREC and KREC levels were observed in the pediatric age group. A significant higher KREC level was observed in females than males after 9–12 years of age but not for TREC. Low TREC or KREC levels were detected in patients diagnosed with mild or severe PIDD. This assay with the established local reference intervals would allow accurate diagnosis of PIDD, and potentially monitoring immune reconstitution following haematopoietic stem cell transplantation or highly active anti-retroviral therapy in the future.