Pasireotide treatment for severe congenital hyperinsulinism due to a homozygous ABCC8 mutation.

ABCC8 and KCJN11 mutations cause the most severe diazoxide-resistant forms of congenital hyperinsulinism (CHI). Somatostatin analogues are considered as secondline treatment in diazoxide-unresponsive cases. Current treatment protocols include the first-generation somatostatin analogue octreotide, although pasireotide, a second-generation somatostatin analogue, might be more effective in reducing insulin secretion. Herein we report the first off-label use of pasireotide in a boy with a severe therapy-resistant form of CHI due to a homozygous ABCC8 mutation. After partial pancreatectomy, hyperinsulinism persisted; in an attempt to prevent further surgery, off-label treatment with pasireotide was initiated. Short-acting pasireotide treatment caused high blood glucose level shortly after injection. Long-acting pasireotide treatment resulted in more stable glycemic control. No side effects (e.g., central adrenal insufficiency) were noticed during a 2-month treatment period. Because of recurrent hypoglycemia despite a rather high carbohydrate intake, the boy underwent near-total pancreatectomy at the age of 11 months. In conclusion, pasireotide treatment slightly improved glycemic control without side effects in a boy with severe CHI. However, the effect of pasireotide was not sufficient to prevent near-total pancreatectomy in this case of severe CHI.

Chondrodysplasia, enchondromas and a chest deformity causing severe pulmonary morbidity in a boy with a PTHLH duplication: A case report.

Parathyroid hormone-like hormone (PTHLH) plays an important role in bone formation. Several skeletal dysplasias have been described that are associated with disruption of PTHLH functioning. Here we report on a new patient with a 898 Kb duplication on chromosome 12p11.22 including the PTHLH gene. The boy has multiple skeletal abnormalities including chondrodysplasia, lesions radiographically resembling enchondromas and posterior rib deformities leading to a severe chest deformity. Severe pulmonary symptoms were thought to be caused by limited mobility and secondary sputum evacuation problems due to the chest deformity. Imaging studies during follow-up revealed progression of the number of skeletal lesions over time. This case extends the phenotypic spectrum associated with copy number variation of PTHLH.

Extensive Ethnic Variation and Linkage Disequilibrium at the FCGR2/3 Locus: Different Genetic Associations Revealed in Kawasaki Disease.

The human Fc-gamma receptors (FcγRs) link adaptive and innate immunity by binding immunoglobulin G (IgG). All human low-affinity FcγRs are encoded by the FCGR2/3 locus containing functional single nucleotide polymorphisms (SNPs) and gene copy number variants. This locus is notoriously difficult to genotype and high-throughput methods commonly used focus on only a few SNPs. We performed multiplex ligation-dependent probe amplification for all relevant genetic variations at the FCGR2/3 locus in >4,000 individuals to define linkage disequilibrium (LD) and allele frequencies in different populations. Strong LD and extensive ethnic variation in allele frequencies was found across the locus. LD was strongest for the FCGR2C-ORF haplotype (rs759550223+rs76277413), which leads to expression of FcγRIIc. In Europeans, the FCGR2C-ORF haplotype showed strong LD with, among others, rs201218628 (FCGR2A-Q27W, r2 = 0.63). LD between these two variants was weaker (r2 = 0.17) in Africans, whereas the FCGR2C-ORF haplotype was nearly absent in Asians (minor allele frequency <0.005%). The FCGR2C-ORF haplotype and rs1801274 (FCGR2A-H131R) were in weak LD (r2 = 0.08) in Europeans. We evaluated the importance of ethnic variation and LD in Kawasaki Disease (KD), an acute vasculitis in children with increased incidence in Asians. An association of rs1801274 with KD was previously shown in ethnically diverse genome-wide association studies. Now, we show in 1,028 European KD patients that the FCGR2C-ORF haplotype, although nearly absent in Asians, was more strongly associated with susceptibility to KD than rs1801274 in Europeans. Our data illustrate the importance of interpreting findings of association studies concerning the FCGR2/3 locus with knowledge of LD and ethnic variation.

Giant aneurysms: A gender-specific complication of Kawasaki disease?

BACKGROUND: Kawasaki disease (KD) is a pediatric vasculitis of unknown origin. Its main complication is the development of coronary artery aneurysms (CAA) with giant CAA at the end of the spectrum. METHODS: In this cohort study, we evaluated the association between patient characteristics and the development of giant CAA based on z-scores. Multivariable, multinomial logistic regression analysis was used to identify variables associated with giant CAA. RESULTS: A total of 301 KD patients, comprising 216 patients without enlargement, 45 with small-sized, 19 with medium-sized, and 21 with giant CAA with all echocardiographies at our center were retrospectively included. Remarkably, 95% of patients with giant CAA were boys. In addition to 'no/late intravenous immunoglobulin (IVIG) treatment', 'male gender' (OR 16.23, 95% CI 1.88-140.13), 'age<1 year' (OR 7.49, 95% CI 2.29-24.46), and 'IVIG re-treatment (9.79, 95% CI 2.79-34.37)' were significantly associated with an increased risk of giant CAA, with patients without enlargement as reference. Compared to patients with medium-sized CAA, 'IVIG re-treatment' was significantly associated with giant CAA. The majority of giant CAA continued to increase in size during the first 40 days. CONCLUSIONS: We identified risk factors associated with an increased risk of giant CAA. The difference in variables between the giant CAA group and the other CAA subgroups suggests a separation between patients with the treatment-resistant giant CAA and the other IVIG-responsive patients, in which gender may be factored as a most relevant genetic trait. The increase in size during the first 2 months indicates the need for repeated echocardiography.

Extracardial Vasculopathy After Kawasaki Disease: A Long-Term Follow-up Study.

BACKGROUND: Kawasaki disease (KD) is a pediatric vasculitis with coronary artery aneurysm (CAA) as a major complication. Controversy exists about cardiovascular risk later in life. The aim of our study was to evaluate whether KD patients are at increased risk, as assessed by carotid intima-media thickness (cIMT). METHODS AND RESULTS: We measured cIMT over 15 years by B-mode ultrasonography in KD patients during follow-up and in unaffected controls (mostly siblings). A multilevel, repeated-measures, linear mixed-effects model was used to evaluate the association between KD and cIMT. A total of 319 patients with 528 measurements were compared with 150 controls. In KD patients, the mean cIMT was increased compared with controls (0.375 mm [95% CI 0.372-0.378 mm] versus 0.363 mm [95% CI 0.358-0.368 mm]; P<0.001). Furthermore, mean cIMT of CAA-negative patients was 0.373 mm (P<0.01 compared with controls), of patients with small-medium CAA was 0.374 mm (P<0.05 compared with controls), and of patients with giant CAA was 0.381 mm (P<0.01 compared with controls). Compared with controls, CAA-negative participants started with an increased cIMT (+0.0193±0.0053 mm, P<0.001) but showed slower progression (-0.0014±0.0006 mm/year, P=0.012). Patients with giant CAA showed a trend toward increased cIMT progression (0.0013±0.0007 mm/year, P=0.058). CONCLUSIONS: We observed a positive correlation between cIMT and KD severity of coronary arteritis at the acute stage. Although initially increased, the cIMT in CAA-negative patients normalized at a later age. In contrast, patients with a history of KD complicated by giant CAA showed a trend toward persistently increased cIMT. These patients may need cardiovascular counseling and follow-up beyond the heart.

Fc-gamma receptor polymorphisms differentially influence susceptibility to systemic lupus erythematosus and lupus nephritis.

OBJECTIVE: To determine relevant Fc-gamma receptor (FcγR) polymorphisms in relation to susceptibility to SLE and LN, and to determine the functional consequences of genetic associations found. METHODS: Using multiplex ligation-dependent probe amplification, copy number regions (CNRs) and relevant known functional single nucleotide polymorphisms of FcγRII and FcγRIII were determined in a LN-enriched cohort of 266 Dutch Caucasian SLE patients and 919 healthy Caucasian controls. Expression of FcγRs on leukocytes was assessed using flow cytometry. RESULTS: In multivariable analysis, low copy number of CNR1 (including FCGR3B; odds ratio (OR) 2.04; 95% CI: 1.29, 3.23), FCGR2A-131RR (OR 2.00; 95% CI: 1.33, 2.99), and the 2B.4 haplotype of FCGR2B (OR 1.59; 95% CI: 1.13, 2.24), but not FCGR2C open reading frame, were significantly (all P < 0.01) and independently associated with susceptibility to SLE. The 2B.4 haplotype was negatively associated with LN and led to surface expression of FcγRIIb on neutrophils and monocytes. CONCLUSION: This study is the first to investigate the most relevant and functional single nucleotide polymorphisms and copy number variations of FcγRII and FcγRIII polymorphisms in one study population, enabling the determination of the individual contribution of each polymorphism in multivariable analysis. Three polymorphisms were shown to be independently associated with susceptibility to SLE. The novel findings of a negative association of the 2B.4 haplotype with LN, and increased expression of FcγRIIb on neutrophils and monocytes as a result of this 2B.4 haplotype warrant future research in the role of these cells and FcγRs in the pathogenesis of SLE and LN.

Carotid Intima-Media Thickness in Patients With a History of Kawasaki Disease.

BACKGROUND: Kawasaki disease (KD) is an acute pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. Concerns have been raised regarding the possibility of a predisposition of KD to premature cardiovascular disease (CVD) risk later in life. Our aim was to assess carotid intima-media thickness (cIMT), as a surrogate marker of CVD risk, in patients with a history of KD compared with unaffected controls. METHODS AND RESULTS: B-mode ultrasound cIMT measurements were performed in 168 patients with a history of KD, and 82 controls; 7 patients were excluded because of incomplete cIMT assessments. Mean cIMT (±SD) was increased in patients with KD compared with controls (0.378±0.030 mm vs. 0.360±0.027 mm, respectively; P adjusted <0.0001). If the cIMTs of CAA-negative patients and controls were plotted against age, increased cIMT was only apparent at young age. In patients with CAA, increased cIMT was observed over the entire age range. CONCLUSIONS: Our findings show that arterial wall thickening is more apparent in patients with a history of KD as compared with controls. In CAA-negative patients, cIMT is indistinguishable from controls at older age, whereas an increased cIMT is observed at any age in patients with CAA, suggesting a more general and severe effect of KD on the arterial wall.

Peripheral Endothelial (Dys)Function, Arterial Stiffness and Carotid Intima-Media Thickness in Patients after Kawasaki Disease: A Systematic Review and Meta-Analyses.

BACKGROUND: Kawasaki disease (KD) is a systemic pediatric vasculitis. Its main complication is the development of coronary arterial aneurysms (CAA), causing an increased risk for ischemia and myocardial infarction. It is unclear whether KD patients, apart from the presence of CAA, have an increased cardiovascular disease (CVD) risk due to the previous systemic vasculitis. The aim of this study was to systematically review and meta-analyse the literature regarding surrogate markers for CVD risk in KD patients. METHODS: Medline and Embase were searched for articles comparing endothelial dysfunction (flow-mediated dilation, nitroglycerin-mediated dilation and peripheral arterial tonometry), vascular stiffness (stiffness index, pulse wave velocity) and carotid intima-media thickness (cIMT) between patients and controls. Two investigators assessed the articles for eligibility and evaluated quality. RESULTS: Thirty studies were included. For all outcomes, moderate to high heterogeneity between studies was found. Most studies reported a decreased flow-mediated dilation in the whole KD- and CAA-positive group compared to controls, while data on CAA-negative patients were conflicting. The stiffness index was increased in the majority of studies evaluating the whole KD- and CAA-positive group, but not in most studies on CAA-negative patients. Mean cIMT was neither significantly increased in the whole KD-group nor in the CAA-positive group nor in most studies studying CAA-negative patients. Studies measuring maximum cIMT were conflicting. CONCLUSION: Literature suggests that surrogate markers for CVD risk in KD patients are increased in CAA-positive but not in CAA-negative patients. This may indicate that CAA-positive patients should be monitored for CVD in later life. The results of this review have to be interpreted with care due to substantial heterogeneity between studies and methodological limitations, as well as the lack of long-term follow-up studies.

Health related quality of life and perceptions of child vulnerability among parents of children with a history of Kawasaki disease.

AIM: Kawasaki disease (KD) is an acute paediatric vasculitis. The psychosocial consequences of this sudden illness for parents are unknown. This study aimed to evaluate health related quality of life (HRQOL) and parental perceptions of child vulnerability (PPCV) in parents of children with KD, and to identify variables associated with PPCV. METHODS: This cross-sectional study included 288 parents (83% mothers) of KD patients (mean age 8.7 years). HRQOL was assessed using the TNO-AZL Questionnaire for Adult's HRQOL (TAAQOL) and PPCV using the Child Vulnerability Scale (CVS). Scores of KD parents were compared with reference groups of Dutch parents. Logistic regression analyses were performed to examine associated variables. RESULTS: The HRQOL of KD parents was comparable to the HRQOL of parents of healthy children. However, KD parents showed significantly higher PPCV, regarding both the median CVS total score and the percentage in the clinical range. No differences were found in CVS outcomes between KD parents and parents of a chronically ill child. None of the studied parental, child and disease characteristics were significantly associated with PPCV. CONCLUSION: Parents perceived their KD child more vulnerable to illness than healthy children, while in reality the majority had fully recovered from KD.

Five years of Kawasaki disease in the Netherlands: a national surveillance study.

BACKGROUND: The aim of this study was to evaluate the incidence, disease presentation, treatment and cardiac outcome of Kawasaki disease (KD) in The Netherlands. METHODS: The national Dutch Pediatric Surveillance Unit was used to prospectively register new KD cases from 2008 through 2012. Questionnaires were sent to pediatricians to obtain clinical information. RESULTS: Nationwide 341 cases were reported during the 5-year study period, of which 319 questionnaires (93.0%) were returned. The mean incidence of KD was estimated to be 5.8/100,000 children <5 years of age. The median age at disease onset was 2.4 years (range 0.1-14.6 years) and 79.2% of cases were <5 years of age. The male-to-female ratio was 1.5 to 1. Incomplete KD was diagnosed in 22.3% of cases and these cases were significantly younger than complete cases [median: 1.1 (0.1-13.7) vs. 2.8 (0.2-14.6) years, P < 0.001]. In total, 308 patients (96.6%) received intravenous immunoglobulins (IVIG). Retreatment with IVIG was given in 71 (23.1%) and additional steroid treatment in 17 patients (5.5%). During the acute phase, coronary artery aneurysms developed in 43 cases (13.5%). Multivariate logistic regression analysis showed that male gender, delay of treatment (>10 days) and IVIG retreatment were independent risk factors for coronary artery aneurysms development. CONCLUSIONS: This prospective study of KD in The Netherlands revealed a mean annual incidence of 5.8/100,000 children <5 years of age. Clinicians should consider the diagnosis of KD in young (male) children with persistent inexplicable fever to start IVIG treatment within 10 days to prevent development of coronary artery aneurysms.

Evaluation of cardiac function by magnetic resonance imaging during the follow-up of patients with Kawasaki disease.

BACKGROUND: Although histopathologic studies suggest persistent myocardial abnormalities after Kawasaki disease (KD), the long-term effects on cardiac function remain to be revealed. We investigated biventricular volumes, function, and the presence of myocardial fibrosis by cardiac magnetic resonance imaging during long-term follow-up of KD. METHODS AND RESULTS: Sixty patients with a history of KD (mean age, 16.9 years; 67% men; median interval after KD onset, 11.6 years) and 20 healthy control subjects (mean age, 17.9 years; 55% men) 12 to 24 years of age underwent cardiac magnetic resonance imaging. Biventricular end-diastolic volume, end-systolic volume, stroke volume, and ejection fraction were determined. Volumetric measurements were indexed for body surface area. Late contrast enhancement was used to detect areas of myocardial fibrosis. Biventricular volumes and function did not differ significantly between patients and control subjects. There were also no significant differences between patients with and without a history of left ventricular dysfunction resulting from KD-associated myocarditis or between patients with and without coronary artery aneurysms. Only those with prior ischemic heart disease had a significantly lower left ventricular ejection fraction compared with unaffected KD cases (left ventricular ejection fraction, 51% versus 57%; P=0.012). Late contrast enhancement was observed in only 2 patients with severe coronary artery aneurysms and was typical for myocardial infarction. CONCLUSIONS: In this cardiac magnetic resonance imaging study evaluating the cardiac function of patients with KD at long-term follow-up, we did not observe a difference in cardiac function between KD patients and control subjects, except for a subgroup of patients with ischemic heart disease as a result of severe coronary artery pathology.

Management of acute and refractory Kawasaki disease.

Acute Kawasaki disease (KD) is treated with high-dose intravenous immunoglobulin (IVIG), which is proven to decrease the incidence of coronary artery aneurysms from 25% to less than 5%. Aspirin is also given, although the evidence base is less secure. There is increasing evidence for steroid therapy as adjunctive primary therapy with IVIG, especially in Asian children. Approximately 10-30% of patients fail to respond to the initial IVIG and are at increased risk of coronary artery aneurysms. The optimal treatment for IVIG-nonresponsive KD remains controversial. Management options include further dose(s) of IVIG, corticosteroids, TNF-α blockade, cyclosporin A, anti-IL-1 and anti-CD20 therapy. In this article, the authors review the current evidence for treatment of acute KD and discuss options for IVIG nonresponders.

Quality of life and behavioral functioning in Dutch children with a history of Kawasaki disease.

OBJECTIVE: The authors evaluated health-related quality of life (HRQOL) and behavioral functioning in patients with a history of Kawasaki disease (KD). STUDY DESIGN: A cross-sectional study was conducted at a tertiary referral center for KD follow-up in 280 patients (mean age 8.6 years, 60.0% male). Patients were eligible when they were aged 0-18 years and had a history of KD. HRQOL was assessed using the TNO-AZL Preschool Children Quality of Life questionnaire for children 0-5 years old and the Pediatric Inventory of Quality of Life Core Scales 4.0 for those 6-18 years old. Behavioral functioning was evaluated using the Strength and Difficulties Questionnaire (8-16 years proxy report and 11-16 years self-report). KD results were compared with Dutch norm data, and patients with and without coronary artery aneurysms were compared. RESULTS: HRQOL was significantly worse for male patients aged 0-5 years on 4 of the 12 TNO-AZL Preschool Children Quality of Life questionnaire scales and for female patients on the motor functioning scale. At an older age, the HRQOL of patients was comparable with the norm population. Coronary artery status did not influence HRQOL. Parents reported more behavioral problems on the hyperactivity and emotional subscale in patients compared with the norm population. CONCLUSIONS: Although at an older age the HRQOL of patients with KD is comparable with the Dutch norm, HRQOL seems to be particularly impaired at younger age. Parents reported more hyperactivity and emotional problems in patients with KD.

Cardiac magnetic resonance imaging for noninvasive assessment of cardiovascular disease during the follow-up of patients with Kawasaki disease.

BACKGROUND: Kawasaki disease (KD) is the most common cause of acquired coronary artery disease in childhood. In KD, the American Heart Association recommends echocardiography for routine coronary artery surveillance and nuclear perfusion scans and conventional coronary angiography in select patients. Cardiac MRI (CMRI) may be a noninvasive and radiation-free alternative. We applied CMRI during the follow-up of patients with KD and assessed the performance of CMRI compared with echocardiography. METHODS AND RESULTS: Patients with KD aged ≥8 years were consecutively included. Sixty-three patients (median age, 14.6 years; 74.6% male sex) underwent a comprehensive CMRI protocol including adenosine stress testing to evaluate coronary artery anatomy, ischemia, and myocardial infarction. All patients underwent CMRI without significant complications. On CMRI, 23 coronary artery aneurysms (CAAs) were identified in 15 patients. CMRI detected thrombus formation in 6 CAAs in 4 patients, wall motion disturbances and ischemia in 4 patients, and delayed hyperenhancement indicating myocardial infarction in 5 patients. Wall motion and perfusion abnormalities were noted in territories supplied by affected coronary arteries. CMRI results were compared with recent echocardiography findings. In 6 of the 15 patients with CAAs on CMRI, CAAs were not detected by echocardiography. CONCLUSIONS: A comprehensive CMRI protocol including adenosine stress testing is feasible to identify coronary artery pathology, ischemia, and myocardial infarction in former patients with KD and compares favorably with echocardiography. CMRI may be used as a noninvasive and radiation-free imaging method for coronary artery surveillance during the long-term follow-up of patients with KD.

[Kawasaki disease: description of a Dutch cohort of 392 patients]. / De ziekte van Kawasaki. Beschrijving van een Nederlands cohort van 392 patiënten.

AIM: To describe the patient characteristics, management and cardiovascular sequelae of Kawasaki disease (KD) in patients taking part in a multidisciplinary follow-up in the Emma Children's Hospital during the period January 1999-June 2010. DESIGN: Retrospective, observational study. METHODS: We included 392 patients who were diagnosed with complete or incomplete KD. Clinical and outpatient statuses were used to collect clinical data. RESULTS: The median age at onset of the disease was 3.2 years (range: 0.1-16.4). The male-to-female ratio was 1.6 : 1. Complete KD was diagnosed in 83.9% of patients. Patients with incomplete KD were younger than those with complete KD: 2.2 versus 3.4 years (both SD: 3.0; p < 0.01). 357 patients (91.1%) were treated with intravenous immunoglobulins; 65 patients (16.6%) received a second intravenous dose. Coronary artery aneurysms were diagnosed in 83 patients (21.2%). Male gender, age < 1 year, incomplete presentation and late start of treatment (> 10 days after start of fever) were shown to be independent risk factors for developing aneurysms. These abnormalities normalized in 50 of the 83 patients. 2 patients died of the disease within a year. 5 patients underwent coronary artery bypass grafting during the follow-up period. CONCLUSION: Kawasaki disease is a rare form of vasculitis seen in children, in which aneurysms of the coronary artery can develop. Clinicians should be alert to the possibility of KD in cases of persistent inexplicable fever, especially in young children, even in the absence of complete clinical disease. A timely start to treatment reduces the risk of developing coronary artery aneurysms.

Impact of PCR for respiratory viruses on antibiotic use: theory and practice.

RATIONALE FOR THE STUDY: Real-time polymerase chain reaction (PCR) for respiratory viruses is more sensitive, yet more expensive, than conventionally used direct immunofluorescence (DIF). We determined the impact of real-time PCR, additional to DIF, on antibiotic prescription in ventilated children with lower respiratory tract infection (LRTI) at admission to the pediatric intensive care unit (PICU). METHODS: First, a multicenter survey study was performed. Subsequently, in a prospective study, children (≤ 5 years) with LRTI were tested at admission by DIF and PCR. Positive DIF results were reported at the end of the first working day. PICU physicians reported antibiotic treatment on the second working day. After informing them of the PCR result antibiotic treatment was reevaluated. RESULTS: The multicenter survey study (94 respondents) showed that PCR decreased antibiotic use (P < 0.001). In the prospective study 38 children were included, of which 19 (50%) were DIF positive. Of the 19 DIF negative patients 12 (63%) were treated with antibiotics before revealing the PCR result; the PCR test was positive in 9 out of 12. Revealing PCR results did not alter antibiotic treatment. In 7 DIF negative patients antibiotics not given, the PCR test was positive. CONCLUSION: In contrast to their responses to the survey study, in real-life PICU physicians did not let their antibiotic prescription be influenced by respiratory real-time PCR in children ventilated for LRTI.

Molecular quantification of respiratory syncytial virus in respiratory samples: reliable detection during the initial phase of infection.

Quantitative real-time PCR for the detection of respiratory syncytial virus (RSV) RNA is increasingly used to study the causal role of RSV in lower airway disease. The objective of our study was to evaluate variations in RSV RNA loads at different steps in the RNA quantification process: (i) variation in RSV RNA load within one sample (step 1), (ii) variation in the load in samples from patients who were sampled twice on the same day (step 2), and (iii) variation in the load between simultaneously taken nasopharyngeal aspirate (NPA) samples and tracheal aspirate (TA) samples (step 3). Thirty-two infants with RSV infection at the pediatric intensive care unit (PICU) were included. NPA and TA samples were taken three times a week during ventilation and were not diluted. Intrasample variation (step 1) was shown to be minimal (<0.5 log(10) particles/ml). Intraday variation (step 2) was the lowest for samples with high viral loads (95% limits of agreement, -1.3 to +0.9 log(10)), whereas it increased for samples with relatively lower viral loads (viral load, <6.0 log(10) particles/ml; n = 138 sample pairs from 20 patients). RSV loads in NPA and TA samples (step 3) were found to be the most comparable during the early phase of infection (95% limits of agreement, -1.5 to +1.4 log(10)). The variation increased during the late phase of infection (i.e., in follow-up samples), with the loads in NPA samples remaining significantly higher than the loads in TA samples (n = 138 sample pairs from 31 patients). In conclusion, quantitative detection of RSV RNA in undiluted mucus is a reliable method to quantify viral loads. Nasopharyngeal aspirate samples collected in the initial phase of infection can be used to predict RSV RNA loads in the lower airways.

A systemic neutrophil response precedes robust CD8(+) T-cell activation during natural respiratory syncytial virus infection in infants.

Severe primary respiratory syncytial virus (RSV) infections are characterized by bronchiolitis accompanied by wheezing. Controversy exists as to whether infants suffer from virus-induced lung pathology or from excessive immune responses. Furthermore, detailed knowledge about the development of primary T-cell responses to viral infections in infants is lacking. We studied the dynamics of innate neutrophil and adaptive T-cell responses in peripheral blood in relation to the viral load and parameters of disease in infants admitted to the intensive care unit with severe RSV infection. Analysis of primary T-cell responses showed substantial CD8(+) T-cell activation, which peaked during convalescence. A strong neutrophil response, characterized by mobilization of bone marrow-derived neutrophil precursors, preceded the peak in T-cell activation. The kinetics of this neutrophil response followed the peak of clinical symptoms and the viral load with a 2- to 3-day delay. From the sequence of events, we conclude that CD8(+) T-cell responses, initiated during primary RSV infections, are unlikely to contribute to disease when it is most severe. The mobilization of precursor neutrophils might reflect the strong neutrophil influx into the airways, which is a characteristic feature during RSV infections and might be an integral pathogenic process in the disease.