Management of anemia in children receiving chronic peritoneal dialysis.

Little information exists regarding the efficacy, modifiers, and outcomes of anemia management in children with CKD or ESRD. We assessed practices, effectors, and outcomes of anemia management in 1394 pediatric patients undergoing peritoneal dialysis (PD) who were prospectively followed in 30 countries. We noted that 25% of patients had hemoglobin levels below target (<10 g/dl or <9.5 g/dl in children older or younger than 2 years, respectively), with significant regional variation; levels were highest in North America and Europe and lowest in Asia and Turkey. Low hemoglobin levels were associated with low urine output, low serum albumin, high parathyroid hormone, high ferritin, and the use of bioincompatible PD fluid. Erythropoiesis-stimulating agents (ESAs) were prescribed to 92% of patients, and neither the type of ESA nor the dosing interval appeared to affect efficacy. The weekly ESA dose inversely correlated with age when scaled to weight but did not correlate with age when normalized to body surface area. ESA sensitivity was positively associated with residual diuresis and serum albumin and inversely associated with serum parathyroid hormone and ferritin. The prevalence of hypertension and left ventricular hypertrophy increased with the degree of anemia. Patient survival was positively associated with achieved hemoglobin and serum albumin and was inversely associated with ESA dose. In conclusion, control of anemia in children receiving long-term PD varies by region. ESA requirements are independent of age when dose is scaled to body surface area, and ESA resistance is associated with inflammation, fluid retention, and hyperparathyroidism. Anemia and high ESA dose requirements independently predict mortality.

Double homozygous missense mutations in DACH1 and BMP4 in a patient with bilateral cystic renal dysplasia.

Renal hypodysplasia (RHD) is characterized by small and/or disorganized kidneys following abnormal organogenesis. Mutations in several genes have been identified recently to be associated with RHD in humans, including BMP4, a member of the transforming growth factor (TGF)-ß family of growth factors. DACH1 has been proposed as a candidate gene for RHD because of its involvement in the EYA-SIX-DACH network of renal developmental genes. Here, we present a patient with renal dysplasia carrying homozygous missense mutations in both BMP4 (p.N150K) and DACH1 (p.R684C). The genotype-phenotype correlation in the family hints at an oligogenic mode of inheritance of the disease in this kindred. Functional analyses of the identified DACH1 mutation in HEK293T cells demonstrated enhanced suppression of the TGF-ß pathway suggesting that both mutations could act synergistically in the development of the phenotype in this patient. This finding provides a model for RHD as an oligo-/polygenic disorder and supports a role for DACH1 in the development of RHD in humans.

High serum adiponectin concentration in children with chronic kidney disease.

Adiponectin (ADPN) counteracts the inflammatory response of the endothelium, which plays an important role in the development of atherosclerosis in patients with chronic kidney disease (CKD). Data in children with CKD are scarce. We examined serum ADPN concentration in 90 children with various renal disorders: 28 with CKD on conservative treatment (CKD), 21 on regular dialysis treatment (D), and 41 after kidney transplantation (Tx); 27 age-matched healthy children served as controls (C). Body mass index (BMI), estimated glomerular filtration rate (eGFR), lipids, homocysteine, high sensitivity CRP (hsCRP), and systolic blood pressure (SBP) were also measured. Mean serum ADPN concentration was significantly higher in patients with CKD (27.3 µg/ml ±15.0), on D (34.2 µg/ml ±14.9), and after Tx (23.6 µg/ml ±9.5) compared with ADPN levels in C (13.5 µg/ml ±6.1) (p < 0.0001). Serum ADPN concentration was inversely related to BMI (p = 0.001) and SBP (p = 0.004). In the multiple linear regression analysis, only SBP remained independently associated with ADPN plasma levels. Data show that children with CKD have significantly higher serum ADPN, even after Tx. The protective antiarthrosclerotic effect of ADPN may be mediated by lower SBP, a finding that deserves further study.

Early angiotensin-converting enzyme inhibition in Alport syndrome delays renal failure and improves life expectancy.

Alport syndrome inevitably leads to end-stage renal disease and there are no therapies known to improve outcome. Here we determined whether angiotensin-converting enzyme inhibitors can delay time to dialysis and improve life expectancy in three generations of Alport families. Patients were categorized by renal function at the initiation of therapy and included 33 with hematuria or microalbuminuria, 115 with proteinuria, 26 with impaired renal function, and 109 untreated relatives. Patients were followed for a period whose mean duration exceeded two decades. Untreated relatives started dialysis at a median age of 22 years. Treatment of those with impaired renal function significantly delayed dialysis to a median age of 25, while treatment of those with proteinuria delayed dialysis to a median age of 40. Significantly, no patient with hematuria or microalbuminuria advanced to renal failure so far. Sibling pairs confirmed these results, showing that earlier therapy in younger patients significantly delayed dialysis by 13 years compared to later or no therapy in older siblings. Therapy significantly improved life expectancy beyond the median age of 55 years of the no-treatment cohort. Thus, Alport syndrome is treatable with angiotensin-converting enzyme inhibition to delay renal failure and therapy improves life expectancy in a time-dependent manner. This supports the need for early diagnosis and early nephroprotective therapy in oligosymptomatic patients.

Fibroblast growth factor 23 and bone metabolism in children with chronic kidney disease.

Fibroblast growth factor 23 (FGF23) is a circulating protein that regulates the renal reabsorption of phosphate and also inhibits 1-alpha-hydroxylase production. In adults FGF23 is increased in chronic kidney disease (CKD) and is an important prognostic factor for cardiovascular morbidity. In order to gain insight into the role of FGF23 and other biochemical variables of bone metabolism in children we studied 69 patients at different stages of CKD. FGF23 was found to be significantly elevated in stage 3 compared with stages 1 and 2 of CKD, preceding significant hyperphosphatemia in stage 4 disease. The highest levels of FGF23 were found in stage 5 compared with stages 1 and 2 CKD. The levels of FGF23 positively correlated with parathyroid hormone and phosphate concentrations and negatively with 1,25-dihydroxyvitamin D, the estimated glomerular filtration rate, and tubular phosphate reabsorption. Using multivariate analysis, hyperphosphatemia and low estimated glomerular filtration rate remained the most significant factors. Thus we found that FGF23 likely has an important role in pediatric calcium and phosphate homeostasis, and in vitamin D metabolism, even at an early stage of CKD. Further studies are needed to clarify the role of FGF23 on the pathogenesis of renal osteodystrophy and its impact on cardiovascular morbidity in pediatric patients with CKD.

Transplantation procedures in children with primary hyperoxaluria type 1: outcome and longitudinal growth.

BACKGROUND: Cure of the metabolic defect in primary hyperoxaluria type 1 (PH1) is possible with liver transplantation (LTx). Preemptive LTx (PLTx) was promoted to prevent chronic kidney disease due to nephrocalcinosis and urolithiasis. However, timing of this procedure is difficult in view of the heterogeneity of PH1 and effective conservative treatment. Combined liver-kidney transplantation (LKTx) is able to cure metabolic defect and replace renal function at the same time and is effective and indicated for patients with or approaching end-stage renal disease (ESRD). Sometimes a sequential approach for LKTx (first liver, then kidney) has been recommended. METHODS: We report on 13 patients with PH1 since 1995 who underwent transplantation procedures in our center for PH1 at a median age of 4.7 (range 1.4-8.9) years. RESULTS: The first two patients, planned for a sequential strategy, died early after LTx because of infectious complications. Four patients underwent PLTx at a median glomerular filtration rate of 65 (range 27-98) mL/min/1.73 m/day (Hoppe et al., Pediatr Nephrol 1996; 10: 488), and three patients still have sufficient residual renal function after a follow-up of median 11.6 years. Seven patients with ESRD received a combined LKTx, including four with infantile oxalosis, and three weighing less than 10 kg. There was no mortality and catch-up growth was observed in most patients. CONCLUSION: In summary and conclusion, transplantation procedures are challenging in PH1, but our results including growth data are encouraging. PLTx remains an option despite the difficulties in timing the procedure. LKTx is indicated for patients with ESRD and is possible even in patients with infantile oxalosis and may improve longitudinal growth.

Estimated one-yr glomerular filtration rate is an excellent predictor of long-term graft survival in pediatric first kidney transplants.

Acute rejection episodes following pediatric renal transplantation have been progressively reduced by recent immunosuppressive regimens. Nevertheless, grafts continue to fail over time and surrogate parameters for long-term RGS are lacking. We investigated post-transplant renal function within the first yr as an independent predictor of long-term RGS in 104 pediatric first kidney transplant recipients (mean age 11.1 +/- 3.9 yr; mean follow-up 8.3 +/- 3.5 yr) transplanted between January 1989 and December 2000. GFR was assessed by use of the Schwartz formula at 30 days and six and 12 months after transplantation, respectively. Patients were further stratified at all times according to GFR: (i) GFR<45 mL/min/1.73 m(2), (ii) GFR 45-80 mL/min/1.73 m(2), and (iii) GFR>80 mL/min/1.73 m(2). Cox regression analysis including factors potentially influencing long-term RGS, e.g., age, gender, transplant yr, HLA-mismatch, underlying renal disease, clinical acute rejection, absolute GFR as well as the change in GFR within the first yr was performed. Graft failure occurred in 24 out of 104 patients (23%) 6.2 yr (mean) after transplantation corresponding to a cumulative five-yr graft survival of 87.5%. GFRs at 30 days and six and 12 months were significantly associated with long-term RGS in the univariate cox regression analysis (GFR at 30 days, p = 0.045; GFR at six months, p = 0.004; GFR at 12 months, p < 0.001). None of the other variables were significant parameters of correlation. Multivariate cox analysis revealed a GFR below 45 mL/min/1.73 m(2) at 12 months after transplantation as the only independent predictor of long-term RGS (hazard ratio 55.9, 95% CI 5.29-591, p = 0.001). GFR at 12 months post-transplant is an excellent surrogate parameter for long-term RGS in children. This parameter might be useful as a primary end-point in short-term pediatric clinical trials.

Efficacy and safety of basiliximab in pediatric renal transplant patients receiving cyclosporine, mycophenolate mofetil, and steroids.

BACKGROUND: Basiliximab, a monoclonal CD25 antibody has proofed effective in reducing acute rejection episodes in adults in various immunosuppressive regimens. The effect of basiliximab in the pediatric population is controversial. METHODS: In a 12-month, double-blind, placebo-controlled trial, renal transplant patients aged 1 to 18 years were randomized to basiliximab or placebo with cyclosporine microemulsion, mycophenolate mofetil, and corticosteroids. The intent-to-treat population comprised 192 patients (100 basiliximab and 92 placebo). RESULTS: The primary efficacy endpoint, time to first biopsy-proven acute rejection episode, or treatment failure by month 6, occurred in 16.7% of basiliximab-treated patients and 21.7% of placebo-treated patients (Kaplan-Meier estimates; hazard ratio 0.72, two-sided 90% confidence interval 0.416-1.26, n.s.). The rate and severity of subclinical rejections in protocol biopsies performed at 6 months posttransplant was higher in the basiliximab group (25.0%) than in the placebo group (11.7%). Patient and death-censored graft survival at 12 months was 97% and 99%, respectively, in the basiliximab cohort, and 100% and 99% among placebo-treated patients (n.s.). Renal function was similar in both treatment groups, and there were no significant between-treatment differences in the incidence of adverse events or infections. CONCLUSIONS: Addition of basiliximab induction to a regimen of cyclosporine microemulsion, mycophenolate mofetil, and steroids resulted in a numerically lower but not significant incidence of biopsy-proven acute rejection versus placebo and excellent graft and patient survival at 1 year in pediatric renal transplant recipients. Whether this numerical difference is a true therapeutic benefit in view of the higher rate and severity of subclinical rejections in the basiliximab group in the protocol biopsy will be investigated in a long-term follow-up study.

Pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on mycophenolate mofetil comedication.

BACKGROUND: The aim of this substudy within a prospective, multicenter, placebo-controlled trial was to assess the pharmacokinetics and immunodynamics of basiliximab in pediatric renal transplant recipients on comedication with mycophenolate mofetil (MMF). METHODS: Eighty-two patients aged 3 to 18 years, receiving cyclosporine microemulsion, MMF, corticosteroids, and basiliximab or placebo were investigated. Basiliximab serum concentrations were determined by ELISA, CD25+, and CD122+ T lymphocytes by flow cytometry. RESULTS: Basiliximab clearance adjusted to body surface area was significantly (P<0.05) greater in children versus adults, but the relatively higher basiliximab dose given to children yielded similar exposure compared with adolescents. A cross-study comparison revealed that MMF reduced basiliximab clearance and prolonged CD25 saturation duration from approximately 5 weeks in the absence of MMF to 10 weeks in the presence of MMF. Basiliximab led to a marked reduction of CD25+ T-cell fraction during the first 8 to 10 weeks posttransplant, but did not specifically affect CD122+ T cells. The majority of biopsy-proven acute rejection episodes (BPAR) were observed after interleukin (IL) 2-R desaturation, whereas about a quarter of BPARs occurred despite adequate IL2-R blockade. CONCLUSIONS: The currently recommended basiliximab dose for pediatric patients, when used with cyclosporine microemulsion and corticosteroids, yielded adequate drug exposure in children and adolescents also under MMF comedication. The observation that about a quarter of BPARs occurred despite adequate IL2-R blockade suggests that another T-cell activation pathway independent of the IL-2/IL-2R pathway is operative, for example, the IL-15 signaling pathway.

The clinical course of steroid-sensitive childhood nephrotic syndrome is associated with a functional IL12B promoter polymorphism.

BACKGROUND: Steroid-sensitive nephrotic syndrome (NS) of childhood is the most common glomerular disease in children. The type and duration of response to corticosteroid therapy are used for clinical classification, and especially patients with steroid dependence often have a complicated course, requiring intensified immunosuppressive treatment. Its cause is still unknown although a cytokine-mediated course of disease has been implicated. Interleukin 12 (IL-12) is critical in determining the type of immune response. The ability of dendritic cells to secrete bioactive IL-12 is associated with a bi-allelic polymorphism within the promoter region of IL12B, the gene encoding the IL-12 p40 subunit. We hypothesized that this genotype may be involved in steroid-sensitive INS. METHODS: Using allele-specific PCR, 79 children with relapsing NS were genotyped for the IL12Bpro polymorphism, and genotype was correlated with clinical phenotype (presence/absence of steroid dependence). RESULTS: Children with the steroid-dependent course are at a significantly higher frequency homozygous for one IL12B allele compared to children without steroid dependence (46.7% and 17.6%, respectively). This genotype has previously been shown to be associated with impaired IL-12 secretion. CONCLUSION: Polymorphisms in the IL12B promoter region associate with two different clinical courses of NS. The IL12Bpro polymorphism may therefore define molecular subgroups with different prognosis. Further studies are needed to evaluate the prognostic value.

Rituximab: is replacement of cyclophosphamide and calcineurin inhibitors in steroid-dependent nephrotic syndrome possible?

The anti-CD20 antibody rituximab has been used successfully as a rescue therapy in some patients with therapy-refractory steroid-dependent nephrotic syndrome (SDNS), including both primary SDNS with minimal changes on biopsy and recurrent focal segmental glomerulosclerosis (FSGS) after renal transplantation. All patients showed remission from steroid dependency for at least 9 months concurring with the reappearance of B lymphocytes that had been eliminated by rituximab. The doses used so far vary between 375 mg/m(2) per dose at weekly intervals for 6 weeks and a single dose of 375 mg/m(2). Until now, with the limited information available, no substantial adverse effects have been reported. However, a recommendation to use rituximab instead of any other established treatment, such as cyclophosphamide, in SDNS cannot be given before clinical studies have been conducted, especially as publication bias cannot be excluded.

CNS or bone marrow involvement as risk factors for poor survival in post-transplantation lymphoproliferative disorders in children after solid organ transplantation.

PURPOSE: To identify prognostic factors of survival in pediatric post-transplantation lymphoproliferative disorder (PTLD) after solid organ transplantation. PATIENTS AND METHODS: A multicenter, retrospective case analysis of 55 pediatric solid organ graft recipients (kidney, liver, heart/lung) developing PTLD were reported to the German Pediatric-PTLD registry. Patient charts were analyzed for tumor characteristics (histology, immunophenotypes, cytogenetics, Epstein-Barr virus [EBV] detection), stage, treatment, and outcome. Probability of overall and event-free survival was analyzed in defined subgroups using univariate and Cox regression analyses. RESULTS: PTLD was diagnosed at a median time of 29 months after organ transplantation, with a significantly shorter lag time in liver (0.83 years) versus heart or renal graft recipients (3.33 and 3.10 years, respectively; P = .001). The 5-year overall and event-free survival was 68% and 59%, respectively, with 59% of patients surviving 10 years. Stage IV disease with bone marrow and/or CNS involvement was associated independently with poor survival (P = .0005). No differences in outcome were observed between early- and late-onset PTLD, monomorphic or polymorphic PTLD, and EBV-positive or EBV-negative PTLD, respectively. Patients with Burkitt or Burkitt-like PTLD and c-myc translocations had short survival (< 1 year). CONCLUSION: Stage IV disease is an independent risk factor for poor survival in pediatric PTLD patients. Prospective multicenter trials are needed to delineate additional risk factors and to assess treatment approaches for pediatric PTLD.

Peritonitis in children who receive long-term peritoneal dialysis: a prospective evaluation of therapeutic guidelines.

In children who are on chronic peritoneal dialysis, peritonitis is the primary complication compromising technique survival, and the optimal therapy of peritonitis remains uncertain. An Internet-based International Pediatric Peritonitis Registry was established in 47 pediatric centers from 14 countries to evaluate the efficacy and safety of largely opinion-based peritonitis treatment guidelines in which empiric antibiotic therapy was stratified by disease severity. Among a total of 491 episodes of nonfungal peritonitis entered into the registry, Gram-positive organisms were cultured in 44%, Gram-negative organisms were cultured in 25%, and cultures remained negative in 31% of the episodes. In vitro evaluation revealed 69% sensitivity of Gram-positive organisms to a first-generation cephalosporin and 80% sensitivity of Gram-negative organisms to a third-generation cephalosporin. Neither the risk factors assumed by the guidelines nor the choice of empiric therapy was predictive of either the early treatment response or the final functional outcome of the peritonitis episodes. Overall, 89% of cases achieved full functional recovery, a portion after relapsing peritonitis (9%). These data serve as the basis for new evidence-based guidelines. Modification of empiric therapy to include aminoglycosides should be considered.

High prevalence of febrile urinary tract infections after paediatric renal transplantation.

BACKGROUND: Adult data suggest that urinary tract infections occur frequently after renal transplantation (RTx) and contribute to mortality and graft loss; data in children are limited. Therefore, we evaluated prevalence, short and long-term morbidity and confounding factors of febrile UTI (fUTI) after paediatric RTx. METHODS: In a retrospective cross-sectional study of three centres, we analysed data on 110 children followed for 4.9+/-3.4 years after successful transplantation. RESULTS: 40/110 (36%) patients had at least one fUTI at a median time of 0.98 years (range 0.02-8.96) after RTx; 11 patients (28%) had recurrent fUTI. Serum creatinine (SCr) rose significantly from 1.15+/-1.13 to 1.83+/-1.69 mg/dl, (P<0.001) during the fUTI, declining to baseline values after treatment. At the last followed-up calculated mean, GFR was comparable between fUTI and non-fUTI groups (75+/-26 vs 71+/-22 ml/min/1.73 m2). During fUTI mean, C-reactive protein (CRP) increased to 123+/-75 mg/l. Febrile UTI were significantly more frequent in girls compared to boys (22/44 vs 18/66, P<0.05) but occurred significantly earlier in boys than in girls [median 0.63 (range 0.02-4.15) vs 1.07 (0.04-8.96) years after RTx; P<0.02]. Also, patients with urinary tract malformations (UTMs) and neurogenic bladder as underlying diagnosis and those with urological surgery prior to transplantation had an increased risk for fUTI. CONCLUSION: fUTI is a frequent complication with significant short-term morbidity especially in girls and children with UTMs, neurogenic bladder and those with urological surgery. Long-term follow-up and prospective studies confirming specific risk factors, preventive measures and impact on graft survival are necessary.

Changes of lymphocyte populations in pediatric steroid-sensitive nephrotic syndrome are more pronounced in remission than in relapse.

BACKGROUND/AIM: Although clinical and immunological findings in steroid-sensitive nephrotic syndrome (SSNS) favor an immunopathogenesis, many issues remain unsolved. Comprehensive studies analyzing cellular and humoral immunity in SSNS are scarce, and few studies addressed the effect of steroids on immunological factors. METHODS: We therefore performed a cross-sectional study of T and B lymphocyte populations in 89 children during the different stages of the disease and related the findings to parameters of humoral immunity and treatment with steroids. RESULTS: In untreated relapse, an increase in the proportion of activated CD3+ lymphocytes with a concomitant reduction of CD19+ B cells was noted compared to healthy controls. Conversely, patients with steroid dependency, relapsing on alternate-day steroids, showed a decline of the absolute numbers as well as proportion of CD4+ lymphocytes but a relative increase in CD19+ B cells, compared to healthy controls. Also untreated remission was characterized by an absolute and relative decrease in CD4+ lymphocytes compared to healthy controls which was accompanied by a significant increase in the proportion of CD8+ and also activated CD3+ lymphocytes. Steroid-induced remission resulted in suppression of absolute and relative CD4+, while absolute and relative B cells were upregulated in this group compared to untreated remission. SUMMARY AND CONCLUSION: Alterations of lymphocyte populations in SSNS are not limited to relapse but seem to be more pronounced in remission and show a different profile with steroid treatment. Changes of lymphocyte populations do not only affect T but also B lymphocytes, which may be of relevance in the pathogenesis of this disorder.

IGF-binding protein-3 fragments in plasma of a child with acute renal failure.

The insulin-like growth factors (IGF) -I and -II promote cellular growth and differentiation of various organs. Their growth-stimulating effects are modulated by a family of six IGF-binding proteins (IGFBPs). Altered patterns of intact and fragmented IGFBPs have been reported in serum and urine of children with chronic renal failure (CRF), and it has been suggested that this may contribute to the growth failure observed in these patients. In the present study, a rapid and comprehensive method is presented to analyze IGFBPs and IGFBP fragments in the plasma of a child with acute renal failure (ARF) who had undergone plasmapheresis. The plasma IGF-I and IGFBP-3 levels were drastically reduced. Plasmapheresis filtrate (3 l) was fractionated by cation-exchange chromatography and reversed-phase high-performance liquid chromatography. The fractions obtained were tested by ligand and immunoblotting. In addition to IGFBP-1 and -4 fragments, the majority of IGF-binding polypeptides were IGFBP-3 immunoreactive. N-terminal sequence analysis of a 17-kDa polypeptide revealed the isolation of a C-terminal fragment of IGFBP-3 starting with Lys 160. The IGF-II-binding polypeptide pattern in the ARF plasma resembles the pattern in hemofiltrate from CRF patients, suggesting that similar or identical proteases are involved in IGFBP-3 fragmentation and common mechanisms may lead to the accumulation of the fragments in both diseases.

Escherichia coli O157 fails to induce a long-lasting lipopolysaccharide-specific, measurable humoral immune response in children with hemolytic-uremic syndrome.

Escherichia coli O157 lipopolysaccharide (LPS)-specific antibodies were measured in sequential serum samples from 131 children with serologically defined E. coli O157-associated hemolytic-uremic syndrome (HUS), using an enzyme immunoassay. On the basis of evaluation of 66 children with culture-proven E. coli O157 infection and serum samples from 132 age-matched control subjects, the assay showed a sensitivity of 95%, 88%, and 74% and a specificity of 99%, 99%, and 98% for IgM, IgA, and IgG, respectively. Anti-O157 LPS antibodies decreased below the cut-off levels in >50% of the children at 11 (IgM), 5 (IgA), and 11 weeks (IgG) after onset of diarrhea and 10, 4, and 10 weeks, respectively, after the onset of HUS. Children with enteropathic HUS fail to develop a long-lasting humoral immune response to the O157 antigen. Incomplete immunity to E. coli O157 may signal a risk for recurrent infections and has implications for serodiagnostic studies.

Saliva IgM and IgA are a sensitive indicator of the humoral immune response to Escherichia coli O157 lipopolysaccharide in children with enteropathic hemolytic uremic syndrome.

Saliva antibodies to Escherichia coli O157 were investigated as markers of the immune response in children with enteropathic hemolytic uremic syndrome (HUS). Paired serum and saliva samples were collected from 22 children with HUS during acute disease and convalescence and were tested for E. coli O157 lipopolysaccharide (LPS)-specific IgM and IgA antibodies by ELISA. Serum and saliva samples from 44 age-matched controls were used to establish the cut-off values. Elevated levels of IgM and/or IgA antibodies to O157 LPS were detected in saliva of 13/13 HUS patients with Shiga toxin-producing E. coli (STEC) O157 in stool culture and from 4 of 5 HUS patients in whom STEC were not detected. These results closely mirrored the results obtained with paired serum samples. In contrast, saliva and serum samples from four children with STEC isolates belonging to O-groups O26, O145 (n = 2), and O165 lacked detectable O157 LPS-specific antibodies. The specificity of the ELISA was confirmed by western blotting. In STEC O157 culture-confirmed cases, the sensitivity of the ELISA was 92% for saliva IgM and IgA, based on the first available sample, and 100% and 92%, respectively, when subsequent samples were included. The specificity was 98% for IgM and 100% for IgA. Children with E. coli O157 HUS demonstrate a brisk, easily detectable immune response as reflected by the presence of specific antibodies in their saliva. Saliva-based immunoassays offer a reliable, noninvasive method for the diagnosis of E. coli O157 infection in patients with enteropathic HUS.

Serum levels of immunoglobulins and IgG subclasses in steroid sensitive nephrotic syndrome.

Alterations of serum immunoglobulins, especially hypogammaglobulinemia (HG), are a frequent finding in steroid sensitive nephrotic syndrome (SSNS). The exact mechanisms are unclear, especially the persistence of HG into remission. Therefore we studied serum immunoglobulins M, A and G including IgG subclasses 1-4 in 44 children with SSNS; 14 were studied during relapse (RL) and 30 in remission (RM). Data were compared with those of 23 healthy controls. In a subgroup of 23 patients (12 in RM and 11 in RL) we also studied IgG-1 specific antibodies to tetanus toxoid and IgG-2 specific antibodies to pneumococcus antigen. Increased serum concentrations of IgM in RL and reduction of serum IgG in RL and RM were confirmed. During relapse, HG was characterized to result from deficiency of IgG-1-3, whereas in early phases of relapse the reduction was due to low IgG-1 only. In RM the deficiency of IgG-2 persisted for 12 months and correlated strongly with the duration of remission ( R=0.60, P<0.0001). IgG-4 levels were not altered in SSNS. In addition, IgG-2 specific antibodies to pneumococcus antigen were significantly reduced only in RL compared to RM ( P<0.05). In conclusion, hypogammaglobulinemia of SSNS is characterized by a different constitution of IgG subclasses. In RL a reduction of serum levels of IgG-1-3 occurs, while low concentrations of IgG-2 might be the explanation for HG in remission of SSNS.

Shiga toxin-producing Escherichia coli infection and antibodies against Stx2 and Stx1 in household contacts of children with enteropathic hemolytic-uremic syndrome.

Ninety-five household contacts (aged 2 months to 73 years) of patients with enteropathic hemolytic-uremic syndrome (HUS) were investigated for the presence of immunoglobulin (Ig) G antibodies to Shiga toxins Stx2 and Stx1 by Western blot assay. Thirty-one percent of the household contacts and 19% of 327 controls had anti-Stx2 IgG (heavy and light chain [H + L]), 5 and 8%, respectively, had anti-Stx1 IgG (H + L), and 3 and 2%, respectively, had both anti-Stx2 and anti-Stx1 IgG (H + L). The incidence of infections with Stx-producing Escherichia coli (STEC) was determined based on the following diagnostic criteria: STEC isolation, detection of stx gene sequences, free fecal Stx in stool filtrates, and serum IgM antibodies against E. coli O157 lipopolysaccharide. Evidence of STEC infection was observed in 25 household contacts, of whom 18 (72%) were asymptomatic and represented a potential source of infection. Six of 13 (46%) household contacts with Stx2-producing E. coli O157:H7 in stool culture developed anti-Stx2 IgG (H + L), compared to 71% of Stx2-associated HUS cases. In individuals showing anti-Stx2 IgG (H + L), the antibody response was directed against the B subunit in 69% of household contacts and 71% of controls, in contrast to 28% of HUS patients. In this investigation controls had a significant increase of the median of IgM antibodies to O157 lipopolysaccharide (LPS) with age, up to the fifth decade. The lack of disease in household contacts with B subunit-specific antibodies, as well as the significantly higher median of anti-O157 LPS IgM antibodies in controls beyond 4.9 years of age, suggests a protective role for anti-Stx and anti-O157 LPS antibodies.