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Background: Immune responses to vaccination are a known trigger for a new onset of glomerular disease or disease flare in susceptible individuals. Mass immunization against SARS-CoV-2 in the COVID-19 pandemic provides a unique opportunity to study vaccination-associated autoimmune kidney diseases. In the recent literature, there are several case reports demonstrating a temporal association of SARS-CoV-2 immunization and kidney diseases. Methods: Here, we present a series of 29 cases of biopsy-proven glomerular disease in patients recently vaccinated against SARS-CoV-2 and identified patients who developed a new onset of IgA nephropathy, minimal change disease, membranous nephropathy, ANCA-associated glomerulonephritis, collapsing glomerulopathy, and diffuse lupus nephritis diagnosed on kidney biopsies post-immunization, as well as recurrent ANCA-associated glomerulonephritis. This included 28 cases of de novo glomerulonephritis within native kidney biopsies and one disease flare in an allograft. Results: The patients with collapsing glomerulopathy were of African American descent and had two APOL1 genomic risk alleles. A brief literature review of case reports and small series is also provided to include all reported cases to date (n=52). The incidence of induction of glomerular disease in response to SARS-CoV-2 immunization is unknown, however, there was no overall increase in incidence of glomerular disease when compared to the two years prior to the COVID-19 pandemic diagnosed on kidney biopsies in our practice. Conclusions: This suggests that glomerulonephritis in response to vaccination is rare, although should be monitored as a potential adverse event.

Objective: Elevated urine albumin to creatinine ratio (ACR) of >30 mg/gm is a widely agreed upon indicator of pathologic albuminuria in children. However, the most reliable specimen to measure ACR in children remains undefined. We assess the range and limits of upright and supine total albumin and ACR in healthy children. Methods: Healthy children age 6 - 18 years completed 24-hour and split upright and supine urine collections. Upright, supine and 24-hour protein, albumin and creatinine were measured. Primary outcomes are range and variation in urine albumin by diurnal status, age, gender, BMI percentile and Tanner stage. Results: In healthy children, with mean age 12.9 year (sd 3.2), upright ACR was 2-fold greater than supine (13.9 vs 6.8 mg/gm, p = 0.02). The range of ACR was much greater in the upright (2 - 323 mg/gm) compared to the supine (1.7 - 76 mg/gm) samples. The average total 24-hour urine albumin was 8.4 mg (sd 9.8) and the mean ACR was 8.9 mg/gm (sd 11.7). The 24-hour albumin increased with age and Tanner stage, but this relationship was not significant after adjusting for BSA or urine creatinine. A supine or upright ACR of >30 mg/gm was found in 5.4% of each group. However, in all subjects with an elevated ACR on an individual upright or supine sample, a second 1st am ACR sample was normal. Conclusions: In healthy children there is a marked diurnal variability in ACR with a higher value from a daytime sample compared to 1st morning specimen. Screening for pathologic albuminuria should always use a first morning urine specimen.

Recently, Schwartz et al. (J Am Soc Nephrol 20:629-637, 2009) used data from the National Institutes of Health-funded Chronic Kidney Disease in Children (CKiD) study to generate new equations for estimating the glomerular filtration rate (eGFR), including an update of the commonly used bedside equation. However, it is unclear if the equation can be generalized to a broader pediatric population. We have used the updated equation on a sample of pediatric patients with less impaired renal function to evaluate the correlation between the new Schwartz equation and measured GFR by iothalamate clearance. We retrospectively analyzed 738 iothalamate clearance tests from 503 patients with a mean serum creatinine of 0.50 mg/dl whose ages ranged from 1 to 16 years. We measured bias, precision, and accuracy and performed a Bland-Altman plot to determine the measure of agreement between the two methods. The mean GFR by iothalamate clearance was 110.6 ml/min/1.73 m(2) and by the new Schwartz estimation 104.7 ml/min/1.73 m(2). The mean difference was 5.84 ml/min/1.73 m(2) (95% CI 4.00-7.67). The newly purposed bedside Schwartz equation therefore demonstrated good agreement with the iothalamate renal clearances in our patient population and appears to be a valid bedside estimating equation for GFR in this sample of children.

Needle phobia—fear of medical devices—is a significant problem in pediatric and adult chemotherapy patients. Stress-reducing medical devices is a new, effective cognitive therapy for needle phobia. Twenty-five pediatric and 25 adult chemotherapy patients were randomly exposed to conventional or stress-reducing decorated butterfly needles and syringes. Emotional stress responses were determined with the Visual Aversion Scale, Visual Analogue Fear Scale, Visual Analogue Anxiety Scale, and Visual Overall Stress Score for each needle and syringe design. Sixty-eight percent of the pediatric and 52% of the adult patients were overtly needle phobic, but children demonstrated significantly more aversion and stress (P < .001). Stress-reducing medical devices effectively and significantly reduced aversion, anxiety, fear, and overall stress, and were 76% effective in preventing overt needle phobia in children and 92% effective in adults (P < .001). One hundred percent of children and adults felt that stress-reducing medical devices should be available in chemotherapy clinics. Needle phobia and stress in pediatric and adult chemotherapy patients are significantly reduced by the use of stress-reducing medical devices.

Normal values of glomerular filtration rate (GFR) in children are often expressed in a value adjusted to adult ideal body surface area. These values work well for many clinical situations, but in infants and children, especially those with atypical body mass, they may not accurately reflect renal function. Most body composition values in children are expressed in developmentally appropriate ranges. Absolute GFR (ml/min) also changes during childhood increasing rapidly in infancy and then gradually with age and body size. Previously, we developed a bedside equation for estimating GFR (ml/min) in children that accounted for changes with age and body size, and which correlated well with steady-state cold iothalamate GFR (ml/min) measurements: GFR (ml/min) = k(*)sqrt[(age(months) + 6)*wt (kg)/serum Cr (mg/dl)], where k=0.95 for females and 1.05 for males. In the present study GFR (ml/min) measured by iothalamate infusion was compared by correlation analysis with estimates calculated from the above equation in 566 children. This equation provides clinicians with a simple bedside method to estimate absolute GFR (ml/min).

Many chemotherapy regimens used in children are nephrotoxic. Accurate dosing of these medications requires that some estimation of glomerular filtration rate (GFR) be performed prior to initiating chemotherapy. However, few studies evaluating normal GFR in children exist. The authors report normal values for GFR for children with nonhematogenous malignancies using a highly accurate method of directly measuring GFR and an equation for estimating absolute GFR in these children. Children with nonhematogenous malignancies with no evidence of renal involvement or prior use of nephrotoxic agents had their GFR measured using an iothalamate infusion methodology. A total of 111 children (males and females) with a mean age = 7.95 years (range 2.8 months-19.5 years) were included in the study. GFR adjusted for body surface area (mL/min/1.73 m 2 ) increases in the first 2 years of life and then plateaus at a level comparable to adult values. GFR adjusted for body surface area for males >2 years = 131.3 &#45 22.5, fem...

Objective. Severe pneumococcal infections have been associated with hemolytic uremic syndrome (HUS), usually with a poor clinical outcome when compared with Escherichia coli O157 gastroenteritis-associated (D+) HUS. We examined our experience with 12 cases of Streptococcus pneumoniae-associated HUS (SP-HUS) and compare it with a cohort of diarrhea-associated HUS (D+ HUS).Methods. A retrospective case survey compared 2 unrelated groups of HUS patients. Demographic factors, clinical indices of disease severity, and outcome were used to compare the 2 groups of HUS patients.Results. Twelve children with SP-HUS were studied. Pneumococcal pneumonia with empyema was the most common precipitating illness (67%), pneumococcal meningitis was present in 17% of children, pneumonia with bacteremia in 8%, and both pneumonia and meningitis in 8%. SP-HUS patients were younger than D+ HUS patients (22.1 vs 49 months) and had more severe renal and hematologic disease than D+ HUS patients. Compared with D+ HUS patients, SP-HUS patients were more likely to require dialysis (75% vs 59%) and had a longer duration of hospitalization (33.2 vs 16.1 days) and duration of thrombocytopenia (11.6 vs 6.8 days). SP-HUS patients were also more likely to require platelet transfusions (83% vs 47%) and needed more platelet (4.7 vs 0.5) and packed red blood cell transfusions (7.8 vs 2.0). The 2 groups did not differ significantly in the incidence of extrarenal HUS complications. There were no deaths in either group. Seven patients have been seen for long-term follow-up; 2 developed end-stage renal disease, and 5 have normal renal function.Conclusions. HUS is a rare but severe complication of invasive pneumococcal infection. Although disseminated intravascular coagulation can also occur in these children, the treatment and follow-up may be different in the 2 conditions. Children with pneumococcal disease and severe hematologic or renal abnormalities should be investigated for evidence of HUS.

Sequelae of Escherichia coli O157 : H7-associated hemolytic uremic syndrome (HUS) 2 – 3 years following an outbreak in Washington State have been prospectively studied to identify predictors of adverse sequelae. Logistic regression analysis was used to examine associations between findings in the acute course and long-term renal and gastrointestinal outcomes. Twenty-one percent of patients had gastrointestinal sequelae, which included cholelithiasis resulting in cholecystectomy (3/29), persistent pancreatitis (2/29), late colon stricture (1/29), and/or glucose intolerance (1/29). Logistic regression analysis found long-term gastrointestinal sequelae were higher in patients who, during HUS, had hypertension [odds ratio (OR) = 21.2, 95% confidence interval (CI) = 1.9 – 164.4, P = 0.01] or gastrointestinal complications (OR = 21.2, 95% CI = 1.9 – 164.4, P = 0.01). Renal sequelae were seen in 35% of patients. One patient (4%) had persistent hypertension and 9 (31%) had minor urinary findings (hematuria or proteinuria). Thrombocytopenia lasting longer than 10 days during the acute illness was associated with a risk for subsequent renal sequelae (OR = 15.0, 95% CI = 1.98 – 1,703.0, P = 0.009). We conclude a high incidence of gastrointestinal sequelae, especially cholelithiasis presenting long after the acute illness, may be seen with HUS. The short follow-up period may underestimate the extent and severity of eventual renal sequelae.

Introduction: Atypical HUS [aHUS] is a rare disease characterized by hemolytic anemia, thrombocytopenia and renal dysfunction due to genetic mutations that lead to uncontrolled activation of the alternative complement pathway. MCP [Membrane Co-Factor protein] or CD46 is a complement factor 3b (C3b) binding molecule which is a cofactor for complement factor I dependent cleavage of C3b. Pathogenic variants in MCP gene account for 5-9% of cases with aHUS. We report the case of a pediatric patient presenting with severe thrombocytopenia, anemia and renal dysfunction who was found to have a novel mutation in MCP and complete recovery with eculizumab therapy. Case report: A previously healthy 9-year-old girl presented with a 2-day history of fever, abdominal pain, emesis and oliguria. There was no history of diarrhea, sick contacts or infectious exposures. There was no known renal disease in her family. Her exam was remarkable for mild scleral icterus, epigastric tenderness but no peritoneal signs. Her labs showed renal failure; BUN 90mg/dl, Cr 4.69 mg/dl, anemia: hemoglobin of 8.4g/dl and severe thrombocytopenia with a platelet count of 4,000/uL. Her peripheral smear had schistocytes, the LDH was elevated at 2511 units/liter and haptoglobin was low at 14 mg/dl. Coagulation parameters were normal. All findings were consistent with severe thrombotic microangiopathy (TMA). A stool assay for Shiga toxin was negative, Her C3 and C4 levels were normal Renal ultrasound showed only increased echogenicity in the right kidney. Urinalysis showed hematuria and proteinuria, culture was negative. Based on triad of hemolytic anemia, thrombocytopenia and renal dysfunction microangiopathic hemolytic anemia (MAHA) was suspected. Pending ADAMTS13 results, plasmapheresis was performed daily (x4) without significant improvement in hemolysis or renal function- as a result. Eculizumab, a human anti-C5 monoclonal antibody was initiated: after the first 2 doses, there was significant improvement in renal function, her hemolysis stopped, and platelet counts began to recover. After 2 months of treatment, renal function, hemoglobin and platelets have all normalized. Her genetic renal panel tested for mutations in 10 genes implicated in aHUS revealed a heterozygous variant in Exon 2 of the CD46 gene (c.132G>A, pMet44Ile) predicted pathogenic by 5/6 algorithms. Based on the patient presentation, normal ADAMTS13 activity (69%), negative Shiga toxin, and response to eculizumab, this case of aHUS was most likely related to the novel CD46 mutation reported for the first time in this work.. Conclusion: Our patient had an unusual presentation of Hemolytic uremic syndrome characterized by severe thrombocytopenia and hemolytic anemia. This case is unique in that we saw moderately severe renal failure, but no other organ system involvement despite severe hematologic aberrations. In atypical HUS,we often see more multiorgan involvement when platelets counts are very low, consistent with more severe thombotoc microangipathy. Her genetic test revealed a novel mutation in the CD46 gene, a regulator of complement activation. She has had an excellent response to eculizumab therapy with complete recovery of renal function and resolution of all hematologic signs of thrombotic microangiopathy, suggesting that his gene variant can be causative of atypical HUS. Disclosures Aaron: Alexion - aHUS Regional Advisory Board: Consultancy, Membership on an entity's Board of Directors or advisory committees. Wong:UpToDate: Consultancy, Patents & Royalties.

Escherichia coli O.157:H7 is a serious and common human pathogen that can cause diarrhea, hemorrhagic colitis, and the hemolytic uremic syndrome (HUS). During a massive outbreak of infection with E coli O157:H7 in January 1993 in Washington State, more than 600 people, mostly children, acquired symptomatic infection, and 37 were hospitalized with HUS at Children's Hospital and Medical Center in Seattle, and six at other hospitals in Washington. Twenty-one (57%) required dialysis. Nineteen (51%) had significant extrarenal pathology: gastrointestinal in 14 patients (38%), cardiovascular in 13 (35%), pulmonary in 9 (24%), and neurological in 6 (16%). Most patients were managed nonoperatively, but three required total abdominal colectomy and one a left colectomy. No child had perforation. Three patients died, all of whom had multisystem disease. The authors recommend (1) that all patients with bloody diarrhea undergo microbiological evaluation for E coli O157:H7 before any surgical intervention; (2) avoidance of antibiotics and antimotility agents in patients with proven or suspected infection with E coli O157:H7 until the safety and efficacy of such interventions have been established in controlled trials; (3) that patients with E coli O157:H7 infections be evaluated for microangiopathic changes consistent with HUS in the week after onset of diarrhea; (4) nasogastric suction for severe symptoms, and frequent abdominal evaluations, tests (electrolytes/amylase), and roentgenograms to exclude treatable abdominal disorders; and (5) institution of hemodialysis for oliguria/anuria, acidosis, or rising creatinine. The authors recommend surgical exploration for toxic megacolon, colonic perforation, acidosis unresponsive to dialysis, or recurrent signs of obstruction or colonic stricture.

We conducted a retrospective analysis of 37 children with Escherichia coli O157:H7-associated hemolytic-uremic syndrome. The infection was traced to contaminated hamburgers at a fast-food restaurant chain. Within 5 days of the first confirmed case, the Washington State Department of Health identified the source and interrupted transmission of infection. Ninety-five percent of the children initially had severe hemorrhagic colitis. Nineteen patients (51%) had significant extrarenal abnormalities, including pancreatitis, colonic necrosis, glucose intolerance, coma, stroke, seizures, myocardial dysfunction, pericardial effusions, adult respiratory disease syndrome, and pleural effusions. Three deaths occurred, each in children with severe multisystem disease. At follow-up two children have significant impairment of renal function (glomerular filtration rate < 80 ml/min/per 1.73 Hm2); both of these children have a normal serum creatinine concentration. Hemolytic-uremic syndrome is the most common cause of acute renal failure in children, and this experience emphasizes the systemic nature of this disease. Clinicians should anticipate that multisystem involvement may occur in these patients, necessitating acute intervention or chronic follow-up. This outbreak of Hemolytic-uremic syndrome also highlights the microbiologic hazards of inadequately prepared food and emphasizes the importance of public health intervention in controlling Hemolytic-uremic syndrome.

The aim of this study was to characterize the 24-h and diurnal variability of urinary protein excretion and identify the prevalence of orthostatic proteinuria (OP) in healthy children. Upright, supine, and 24-h total urinary protein (UrTP) and creatinine clearance (CrCl) were measured in 91 healthy children ages 6–19 years. Urinary protein and creatinine excretions were calculated and examined by gender, age, Tanner stage, and body mass index (BMI). Orthostatic proteinuria (OP) was defined as a 24-h UrTP >100 mg/m2 with a normal supine UrTP (10 years and BMI >85%. In children with OP, a first morning UPcr shows a value in the normal range, whereas a random daytime UPcr is elevated. There exists a diurnal variability in urinary protein excretion that is exaggerated in participants with OP. UPcr reliably estimates 24-h UrTP. Using current pediatric criteria, OP is very common, particularly in boys. A normal first morning UPcr ratio indicates that a child with elevated random urinary protein has OP.

The mortality rate in children with ESRD is substantially lower than the rate experienced by adults. However, the risk of death while awaiting kidney transplantation and the impact of transplantation on long-term survival has not been well characterized in the pediatric population. We performed a longitudinal study of 5961 patients under age 19 who were placed on the kidney transplant waiting list in the United States. Of these, 5270 received their first kidney transplant between 1990 and 2003. Survival was assessed via a time-varying nonproportional hazards model adjusted for potential confounders. Transplanted children had a lower mortality rate (13.1 deaths/1000 patient-years) compared to patients on the waiting list (17.6 deaths/1000 patient-years). Within the first 6 months of transplant, there was no significant excess in mortality compared to patients remaining on the waiting list (adjusted Relative Risk (aRR) = 1.01; p = 0.93). After 6 months, the risk of death was significantly lower: at 6-12 months (aRR = 0.37; p < 0.001) and at 30 months (aRR 0.26; p < 0.001). Compared to children who remain on the kidney transplant waiting list, those who receive a transplant have a long-term survival advantage. With the potential for unmeasured bias in this observational data, the results of the analysis should be interpreted conservatively.

C1q nephropathy (C1qN) is an uncommon disorder seen in children and adults with nephrotic syndrome and non-specific urinary findings. It has been described with minimal change nephrotic syndrome (MCNS), focal segmental glomerulonephritis and isolated mesangial proliferative glomerulonephritis. We describe nine children with MCNS and mesangial C1q deposition. These children had a median age of 2.7 years at diagnosis (range 1.3–15 years), 56% were male and 78% were Hispanic. We compared these children to concurrent patients with nephrotic syndrome and biopsy-proven MCNS. We found that the C1qN patients were more likely than MCNS children to require chronic immunosuppression with calcineurin inhibitors or mycophenolate mofetil to maintain remission. However, all children were able to achieve and sustain clinical remission of nephrotic syndrome. Children with C1qN and minimal change histology have an increased frequency of frequently relapsing and steroid-unresponsive disease, but they can attain prolonged remission and stable renal function with calcineurin inhibitor or mycophenolate mofetil therapy.

To determine the incidence and prevalence of neuropsychiatric systemic lupus erythematosus (NPSLE) and glomerulonephritis in ethnically diverse pediatric onset SLE inpatient and outpatient populations.Seventy-five pediatric onset patients with SLE including Native American, Asian, Black, Spanish-American, and Caucasian subjects were evaluated prospectively and cross sectionally. During the 6 year study, 55 patients became inpatients. Subjects underwent medical interview, physical examination, laboratory review, neuropsychiatric inventory, and chart review. Classification of NPSLE was accomplished with the 1999 ACR NPSLE case definitions.Prospectively, NPSLE occurred in 95% of pediatric SLE patients and was more common than glomerulonephritis (55%; por = 0.0001). NPSLE prevalence (%) and incidence (event/person/yr) were as follows: headache 72%, 95; mood disorder 57%, 0.41; cognitive disorder 55%, 0.49; seizure disorder 51%, 0.94; acute confusional state 35%, 0.6; anxiety disorder 21%, 0.28; peripheral nervous system disorder 15%, 0.16; cerebrovascular disease 12%, 0.32; psychosis 12%, 0.16; chorea 7%, 0.01; demyelinating syndrome 4%, 0.01; and myelopathy 1%, 0.001. Cross sectionally, active NPSLE was present in 93% of inpatients and 69% of outpatients. When only serious forms of NPSLE were considered (stroke, seizures, major cognitive disorder, chorea, psychosis, major depression, acute confusional state), serious or life-threatening NPSLE occurred in 76% of all SLE subjects prospectively, and in 85% and 40% of inpatients and outpatients cross sectionally, which in each instance was more common than glomerulonephritis (por = 0.001).NPSLE is one of the most common serious complications of pediatric SLE, and is particularly increased in pediatric inpatients.

Hypoalbuminemia and risk of death in pediatric patients with end-stage renal disease. Background Although serum albumin is a marker for malnutrition and associated with a higher mortality in adult patients with end-stage renal disease (ESRD), the risk of death associated with serum albumin is unknown in pediatric patients with ESRD. We evaluated the association between serum albumin and death among pediatric patients initiating dialysis. Methods Data from the United States Renal Data System (USRDS) were used to identify all patients under the age of 18Who initiated dialysis between January 1, 1995 and December 31, 1998. Using the Cox proportional hazards models, the association between serum albumin obtained 45 days prior to dialysis initiation and death was estimated, controlling for demographic factors, dialysis modality, and anthropometric measures. Results Of 1723 patients included in the analysis, there were 93 deaths over 2953 patient-years of observation. The multivariate analysis demonstrated that each -1 g/dL difference in serum albumin between patients was associated with a 54% higher risk of death [adjusted relative risk (aRR), 1.54; 95% confidence interval (CI), 1.15 to 1.85; P = 0.002]. This was independent of glomerular causes for their ESRD and other potential confounding variables. Conclusions Pediatric patients initiating dialysis with hypoalbuminemia are at a higher risk for death. This finding persists after adjusting for glomerular causes for ESRD and other potential confounding variables. Low serum albumin at dialysis initiation is an important marker of mortality risk in pediatric ESRD patients.

A prospective randomized study of the use of recombinant human erythropoietin (rHuEPO) in children with chronic renal disease was conducted to assess dosing requirements and side effects. Forty-four children with chronic renal failure, aged 4 months to 21 years, were studied. Twenty-five patients were pre dialysis, 10 on peritoneal dialysis, and 9 on hemodialysis. Patients received either 150 U/kg per week or 450 U/kg per week divided thrice weekly of rHuEPO for 12 weeks or until target hemoglobin (Hb) was attained. Dose was then adjusted to maintain a normal Hb. Eighty-two percent of patients reached target Hb by 7.9+/-5.6 weeks (mean+/-SD); 95% of patients in the high-dose group and 66% in the low-dose group reached target Hb within 12 weeks. The overall median rHuEPO dose at target Hb was 150 U/kg per week. Hemodialysis patients tended to require more rHuEPO to maintain a normal Hb (median 250 U/kg per week). Transfusion requirements and panel-reactive antibody levels decreased during the 12 weeks. Iron deficiency and/or hypertension occurred in 30% of children. In conclusion, rHuEPO at 150 U/kg per week is safe and effective in treating anemia in children with chronic renal disease.

We reviewed our center’s experience with nightly automated peritoneal dialysis (APD) as maintenance renal replacement therapy (RRT) for infants and children under the age of 5 years and compared it with national dialysis and transplant data. A retrospective chart review of 19 consecutive patients with the onset of end-stage renal disease (ESRD) before 5 years of age (mean = 1.8 years) between June 1988 and June 1994 was performed. All patients received nightly APD, supplemental feedings, calcitriol, erythropoietin, and 10 of 19 were on growth hormone (rhGH) therapy. The growth of our patients was maintained or improved during the study period, with the 10 of 19 on rhGH gaining a mean of one standard deviation in height when followed for 2 years. Our school-age children were all in age-appropriate classes. There were no deaths in our group; the incidence of peritonitis was lower than in national data. We conclude that APD is a realistic option for the treatment of ESRD in the 0- to 5-year-old child. Because of the improved graft and patient survival in older children, APD in a specialized center might be the RRT of choice in this age group, allowing good growth and development while maximizing the chances of an eventual and successful renal transplant.

Megakaryocytes are relatively rare components of human bone marrow, making the study of their maturation difficult. Phorbol esters can act as differentiating agents in a number of cell systems including murine megakaryocytes. We report the effects of phorbol esters on the previously described long-term human megakaryocytic leukemia cell culture, EST-IU. While two nontransforming phorbols fail to affect these cells, the transforming phorbol 12-O-tetradecanoylphorbol-13- acetate (TPA) induces a phenotype with characteristics of more mature megakaryocytes in a dose-related manner. This phenotype includes an increased adherence to untreated plastic or glass, polyploidization, an increase in cell size, and increased expression of both platelet glycoproteins and factor VIII-related antigen. Two-color flow cytometric analysis allowed simultaneous determinations of DNA content and the expression of surface membrane antigens or alpha-granule constituents, providing evidence that nuclear, membrane, and cytoplasmic maturation occur in parallel in this cellular system. TPA- induced maturation of EST-IU cells provides an important new cellular model for the further study of human megakaryocyte development.

Role of the complement membrane attack complex (C5b-9) in mediating experimental mesangioproliferative glomerulonephritis. Previous studies have demonstrated that most pathologic changes in the antithymocyte serum (ATS) model of mesangioproliferative glomerulonephritis are complement-dependent. These include mesangiolysis, glomerular platelet infiltration, mesangial cell proliferation, mesangial cell production of growth factors and phenotypic change to express α -actin, glomerular macrophage infiltrate, mesangial matrix expansion, and proteinuria. The mechanism by which complement mediates these effects has not been defined. Because neutrophils do not participate in the ATS model, we hypothesized that the complement effects observed are consequent to glomerular cell insertion of the C5b-9 membrane attack complex of complement. This hypothesis was tested utilizing PVG rats which exhibit an absence of C6 inherited in an autosomal recessive pattern. C6 deficient (C-) PVG rat serum activated by zymosan produced normal amounts of C5a compared to normocomplementemic (C+) PVG rat controls but no C5b-9. When ATS was induced, C- PVG rats had a significant and marked reduction in mesangiolysis, platelet infiltration, mesangial cell proliferation, α -actin expression, macrophage infiltration, collagen IV deposition, and proteinuria compared to C+ controls. The reduction in each of these parameters was comparable to that achieved by systemic complement depletion of C+ PVG rats with cobra venom factor. These findings establish the role of C5b-9 in mediating each of the complement-dependent features of the ATS model and indicate that C5b-9 accounts for all of the complement-mediated effects observed. This study provides the first documentation of a functional role for C5b-9 in mediating a non-membranous inflammatory type of glomerular injury in vivo