Elevated interleukin-18 levels in the urine of nephrotic patients

BACKGROUND/AIM: The etiology of minimal-change nephritic syndrome (MCNS) is obscure. It has been speculated that T cells play a role in the pathogenesis of MCNS. Interleukin (IL)-18, a novel immunoregulatory cytokine with potent inferon-gamma-inducing activities, may play an important role in T-helper type 1-mediated immune responses. To examine further the possible role of IL-18 in nephrotic syndrome (NS), in the present study we measured IL-18 levels in the urine in different clinical stages of MCNS. The aim of this study was to investigate the involvement of IL-18 in MCNS. METHODS: Urine samples were obtained from 20 MCNS patients. The disease controls included 20 patients with IgA nephropathy. The samples were assayed for IL-18 protein by a sandwich enzyme-linked immunosorbent assay. RESULTS: Compared with normal controls, significantly increased urinary levels of IL-18 were detected in MCNS patients with the NS. The urinary IL-18 (uIL-18) levels correlated with the degree of proteinuria in MCNS patients. Moreover, when individual MCNS patients were followed through their clinical illness, uIL-18 levels were increased during the active phase and decreased as the patients went into remission. CONCLUSIONS: These results indicate that uIL- 18 is detectable in a subgroup of patients with active NS and correlates to their disease activity in patients with MCNS. Our findings support the notion that IL-18 may play a role in the pathophysiology of NS.     

Elevated vascular endothelial growth factor levels in the urine of patients with minimal-change nephrotic syndrome

BACKGROUND: Vascular endothelial growth factor (VEGF) is a selective endothelial mitogen and vascular permeability factor (VPF), that is mainly produced by activated monocytes/macrophages and T cells. To our knowledge, very little is known about the involvement of VEGF in minimal-change nephrotic syndrome (MCNS). The aim here was to define further the involvement of VEGF in MCNS. PATIENTS AND METHODS: Urine samples were obtained from 20 MCNS patients. The disease controls included 20 patients with IgA nephropathy (IgAN). The samples were assayed for VEGF protein by a sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with normal controls, markedly increased urinary levels of VEGF were detected in both MCNS and IgAN patients with the nephrotic syndrome (NS). The urinary VEGF (uVEGF) levels correlated with the degree ofproteinuria in MCNS and IgAN patients. Moreover, when individual MCNS patients were followed through their clinical illness, uVEGF levels were increased during the active phase and decreased as the patients went into remission. Our main concern is to distinguish between two possibilities: Increases in uVEGF excretion might indeed relate to specific glomerular pathology and thus have a pathophysiological role. Alternatively, uVEGF may be derived from the circulation and as such may be nothing more than an assay for proteinuria. In fact, given the strict correlation between uVEGF excretion and the amount of proteinuria, the second possibility appears quite conceivable. CONCLUSION: Therefore, this may be a coincidental finding which has no bearing on the pathophysiology of MCNS.     

Increased urinary excretion of interleukin-17 in nephrotic patients

BACKGROUND/AIM: Interleukin (IL)-17 is a newly discovered cytokine that is secreted by activated memory CD4+ T cells and modulated the early stage of immune response. To elucidate the pathophysiology of minimal-change nephrotic syndrome (MCNS), we focused on IL-17, which is one of the key factors in regulating an inflammatory response, and thus determined the daily excretion of IL-17 in urine. METHODS: For this purpose, excretion levels of IL-17 were measured in the urine of patients with MCNS during relapse and remission using a highly sensitive sandwich enzyme-linked immunosorbent assay. The data obtained were compared with levels of daily urinary excretion of IL-17 in patients with IgA nephropathy (IgAN). A group of healthy subjects served as control. In both experimental groups urine levels of IL-17 excretion were plotted against their daily urinary protein excretion. RESULTS: We demonstrated increased levels of IL-17 excretion in the urine of patients with MCNS and IgAN as compared to the non-nephrotic and healthy controls. In MCNS the daily urinary IL-17 (uIL-17) excretion was increased and returned to baseline with remission of the nephrotic syndrome (NS). We also demonstrated a positive correlation between urinary protein excretion and daily uIL-17 excretion. CONCLUSION: Taken together, these data indicate that uIL-17 excretion is increased during the NS, suggesting the possibility that daily uIL-17 excretion may reflect the disease activity of NS.     

Effects of interleukin-15 on vascular permeability factor release by peripheral blood mononuclear cells in normal subjects and in patients with minimal-change nephrotic syndrome

The characteristic function of interleukin (IL)-15 appears to be its ability to mimic the stimulatory action of IL-2 on lymphocytes by utilizing part of the IL-2 receptor complex. To gain insight into the immunoregulatory properties of this cytokine in patients with minimal-change nephrotic syndrome (MCNS), we analyzed effects of IL-15 on vascular permeability factor (VPF) release in vitro. Peripheral blood mononuclear cells (PBMC) were isolated from 16 patients with MCNS, 16 patients with IgA nephropathy (IgAN) and 16 healthy controls. Cells were stimulated with concanavalin A (Con A) and the VPF was assessed using the method of Lagrue with minor modifications. PBMC secreted significantly increased amounts of VPF under stimulation with Con A in patients with MCNS and IgAN patients with the nephrotic syndrome as compared with normal controls. Here we have demonstrated, for the first time, that addition of IL-15 to PBMC obtained from nephrotic patients as well as from normal controls increased Con A-induced release of VPF by 250%. This stimulatory effect was found highly significant and was dose-dependent. The effect of IL-15 on the secretion of VPF was specific, since a complete reversion was obtained with a neutralizing antibody to human IL-15. Our findings reveal that IL-15 has the potential to function as an immunoregulatory molecule of PBMC VPF release. In addition, IL-15 had similar effects to IL-2 in terms of its capacity to upregulate VPF release. Taken together, our data emphasize a positive regulatory role for IL-15 in inducing the release of VPF when present at optimal levels. Therefore, IL-15 antagonists may provide a basis for immune intervention in the pathophysiology of VPF.     

Interleukin-13 genetic polymorphisms in Singapore Chinese children correlate with long-term outcome of minimal-change disease.

BACKGROUND: Minimal-change nephrotic syndrome (MCNS) has been associated with atopy. As interleukin-13 (IL-13) has been implicated in the pathogenesis of MCNS, we postulated that IL-13 genetic polymorphisms could influence either susceptibility or clinical course of the disease. METHODS: Seventy-two Singapore Chinese children with MCNS and 78 normal controls were screened for single nucleotide polymorphisms (SNPs) in the IL-13 gene by direct sequencing. Allele and genotype frequencies of these SNPs were determined and their relationship with different clinical courses was analysed. RESULTS: Six SNPs were identified in the 5' promoter, exon 4 and 3' untranslated region (3'UTR). The three SNPs in the 3'UTR--4738 (G/A), 4793 (C/A) and 4926 (C/T)--were in tight linkage disequilibrium (Delta > or = 0.99). There was no difference in allele or genotype frequencies between MCNS children and normal controls. However, there was a significantly lower frequency of allele 4738G in those MCNS children who were still relapsing after 5 years of follow-up (G = 0.52), compared with those in complete remission (G = 0.72; P<0.05) and normal controls (G = 0.69; P<0.05). Haplotype analysis showed a significantly higher frequency of the GCC haplotype in controls and MCNS patients in complete remission (chi2 = 6.35; P<0.02), while the frequency of AAT haplotype was higher in those MCNS children still relapsing after 5 years of follow-up (chi2 = 5.38; P<0.02). Moreover, peripheral blood mononuclear cell IL-13 mRNA expression in patients with haplotype AAT was significantly higher than in those with haplotype GCC. CONCLUSIONS: These results suggest that genetic polymorphisms in the 3'UTR of the IL-13 gene correlate with long-term outcome of MCNS, rather than disease susceptibility, in Singapore Chinese children.     

Polymorphism of the interleukin-4, interleukin-13, and signal transducer and activator of transcription 6 genes in Indonesian children with minimal change nephrotic syndrome

BACKGROUND/AIMS: Minimal change nephrotic syndrome (MCNS) in children is frequently associated with allergy and immunoglobulin E (IgE) production. T-helper subtype 2 cytokines, such as interleukin (IL)-4 and IL-13, have been implicated in the regulation of IgE production. We investigated the associations of gene polymorphisms of IL-4, IL-13, and signal transducer and activator 6 (STAT6) in Indonesian children with MCNS (n = 84) and controls with neither allergic nor renal disease (n = 61). METHODS: Polymerase chain reaction-restriction fragment length polymorphism was used to determine the IL-4 promoter gene polymorphism (-590C/T) and IL-13 gene polymorphism (4257G/A), and direct sequencing was used for the STAT6 3S untranslated region (2964G/A) polymorphism. RESULTS: There was a significant difference between the MCNS group and the controls in the genotypic distribution of IL-4 and IL-13 gene polymorphism. In the case of the IL-4 promoter gene, the frequency of the CC homozygote was significantly lower in the MCNS group than in the controls, while, in the case of IL-13, the frequency of the GG homozygote was significantly lower in the MCNS group. However, there was no difference between the MCNS group and the controls in the STAT6 gene polymorphism. CONCLUSION: The genetic variations in the IL-4 and IL-13 genes may be associated with predisposition to MCNS.     

The urinary podocyte as a marker for the differential diagnosis of idiopathic focal glomerulosclerosis and minimal-change nephrotic syndrome

BACKGROUND/AIMS: Detection of podocytes in the urine sediment of children indicates that severe podocyte injury occurred in the glomerulus. Focal glomerulosclerosis (FGS) and minimal-change nephrotic syndrome (MCNS) are kidney diseases characterized by massive proteinuria. The aim of the present study was to determine whether urinary podocytes can be detected in patients with idiopathic FGS or MCNS and whether immunosuppression therapy alters these cells. METHODS: Twenty patients with MCNS (nephrotic stage, n = 12; remission stage, n = 8), 15 patients with FGS and 20 healthy controls were included in the present study. Urinary podocytes were stained by immunofluorescence. All patients with MCNS at the nephrotic stage received prednisolone for 6 months, and all patients with FGS received some form of immunosuppression therapy including prednisolone, cyclophosphamide or mizoribine for 12 months. RESULTS: The 12 nephrotic-stage MCNS patients achieved remission after treatment. Seven of the 15 FGS patients also achieved remission, but the other 8 remained in the nephrotic stage. Urinary podocytes were not detected in any patient with MCNS nor were they detected in healthy controls. Urinary podocytes were detected in all FGS patients (mean, 4.2 cells/ml) before treatment and the number of cells decreased in the 7 patients who achieved remission. The number of podocytes was unchanged in the other 8 patients even after treatment. CONCLUSION: Urinary podocytes may be a useful diagnostic indicator for differentiation between FGS and MCNS. These cells may also mark disease progression in cases of FGS.     

Urinary levels of macrophage migration inhibitory factor in patients with IgA nephropathy

BACKGROUND/AIM: The processes involved in development of IgA nephropathy (IgAN) are not yet well understood. Macrophage migration inhibitory factor (MIF) is a potent pro-inflammatory cytokine and is an essential component of immune and inflammatory responses. To examine further the possible role of MIF in IgAN, we measured MIF levels in the urine. The purpose of the present study was to evaluate the involvement of MIF in IgAN. METHODS: Urine samples were obtained from 20 IgAN patients. The disease controls included 20 patients with minimal-change nephrotic syndrome (MCNS). A group of healthy subjects served as control. The samples were assayed for MIF protein by a sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: The MIF levels in the urine of patients with IgAN examined were significantly higher than those of the healthy control subjects. In contrast, the levels of urinary MIF (uMIF) in patients with MCNS did not differ significantly from normal values. In IgAN patients, uMIF significantly correlated with the magnitude of proteinuria, but not with the grade of hematuria. We also investigated the relationship between uMIF levels and pathological features. Among patients with IgAN, uMIF levels were significantly correlated with the grade of glomerular crescent formation and that of mesangial cell proliferation. There was also a significant correlation between uMIF levels and the number of both intraglomerular and interstitial macrophages. CONCLUSION: Although the underlying mechanisms remain to be determined, these data provide evidence that urinary excretion of MIF is increased in IgAN patients with active renal lesions.     

Expression of Fc epsilon receptor 2 in minimal change nephrotic syndrome]

In order to clarify the mechanism for elevation of serum IgE level in minimal change nephrotic syndrome (MCNS), we investigated Fc epsilon receptor 2 (Fc epsilon R2/CD23) expression, using fluorescein isothiocyanate (FITC) labeled anti-CD20 monoclonal antibody, phycoerythrin (PE) labeled anti-CD23 monoclonal antibody and two-color flow cytometry. Moreover, serum IgE level was examined by radio-immunosorbent test. The subjects included 25 cases of MCNS, 17 cases of focal glomerular sclerosis (FGS), and 25 healthy volunteers as controls. The patients in the nephrotic stage of MCNS demonstrated significantly elevated levels of serum IgE, while those in the remission stage of MCNS showed no change in their serum IgE levels. In patients with nephrotics of MCNS, CD23+ cells, CD20+ CD23+ cells and CD23/CD20 ratio were significantly increased compared to normal controls. Furthermore, CD23/CD20 ratio in MCNS was significantly correlated with serum IgE level. Concerning FGS, there were no differences in serum IgE level and Fc epsilon R2 expression compared to those of normal controls. These results suggest that Fc epsilon R2 expression may be important in the mechanism of elevated serum IgE level in MCNS.     

T-cell subsets,interleukin-2 receptor expression and production of interleukin-2 in minimal change nephrotic syndrome

This study was designed to investigate T-lymphocyte subsets interleukin-2 receptor (IL-2R) expression and IL-2 production in minimal change nephrotic syndrome (MCNS). Peripheral blood T-lymphocytes and IL-2R expression were analysed using fluorescein isothiocyanatelabelled CD3, CD4, CD8 and CD25 monoclonal antibodies with flow cytometry. IL-2 production was determined by enzyme immunoassay. Ten children with MCNS in relapse and in remission were evaluated. Thirteen healthy children served as controls. The patients in relapse demonstrated a moderate decrease in the total absolute lymphocyte counts and CD8(+) T-lymphocytes compared with controls (P<0.05) and had a greatly increased IL-2R expression in frashly isolated, unstimulated peripheral lymphocytes compared with patients in remission and controls. While this was not statistically significant, IL-2R expression on cultured lymphocytes stimulated with phytohaemagglutinin was significantly elevated in relapse compared with those in remission and controls (P<0.05). IL-2 production did not correlate well with IL-2R expression and there was no significant difference between the groups. Our results suggest that T-cell subset changes and high IL-2R expression on peripheral lymphocytes may indicate the presence of stimulated T-cell populations in MCNS which could contribute to the immunopathogenesis.     

Transforming growth factor-beta1 inhibits vascular permeability factor release by T cells in normal subjects and in patients with minimal-change nephrotic syndrome

BACKGROUND/AIM: A lymphokine, the vascular permeability factor (VPF), which increases vascular permeability, has been characterized in minimal-change nephrotic syndrome (MCNS). Transforming growth factor-beta (TGF-beta) is an immunosuppressive cytokine that inhibits proliferation, cytokine production, and cytotoxic activity of T cells and natural killer cells. We, therefore, investigated the effects of TGF-beta1 on the release of VPF by peripheral blood T cells from MCNS patients. The aim of our study was to determine the in vitro immunosuppressive capacity of TGF-beta1 in patients with MCNS. METHODS: To further test the effect of TGF-beta1 on concanavalin A (Con A)-induced VPF release, normal and MCNS T cells were stimulated with 5 microg/ml of Con A in the presence or absence of TGF-beta1, and the culture supernatants were tested for the presence of VPF by the method of Lagrue et al. The disease controls included 16 patients with IgA nephropathy. RESULTS: Significantly increased spontaneous and Con A-stimulated secretion of VPF was detected in T-cell cultures of MCNS patients with the nephrotic syndrome as compared with those of normal controls. Addition of TGF-beta1 to these cultures inhibited the release of VPF in a dose-dependent manner. The effect of TGF-beta1 on the release of VPF was specific, since a reversion was obtained with a neutralizing monoclonal antibody to human TGF-beta1. CONCLUSION: Together, our data demonstrate that TGF-beta1 antagonizes the ability of T cells to release VPF, and suggest a role of TGF-beta1 in the pathophysiology of VPF in vitro.     

Interleukin-15 and interleukin-12 have an additive effect on the release of vascular permeability factor by peripheral blood mononuclear cells in normals and in patients with nephrotic syndrome.

BACKGROUND: The vascular permeability factor (VPF) is a lymphokine that has been shown to play a role in minimal-change nephrotic syndrome (MCNS). A better understanding of the mechanisms that upregulate VPF release is of basic importance to control the immune system in nephrotic syndrome (NS). Interleukin (IL)-15 is a key inducer of differentiation of uncommitted T helper cells, which regulates cellular immunity. The cytokine IL-15 appears to mimic the stimulatory activity of IL-2 on T cells. PATIENTS AND METHODS: In the present report, we studied the ability of IL-15, alone or in combination with IL-12, to influence the release of VPF by peripheral blood mononuclear cells (PBMC) from nephrotic patients. We have analyzed the release of VPF by concanavalin-A- (Con A) stimulated PBMC in normals, 16 patients with MCNS and 16 patients with IgA nephropathy (IgAN). RESULTS: In both patient groups 50% had a proteinuria below 0.8 g/day. We demonstrate that nephrotic, but not non-nephrotic patients (both MCNS and IgAN), exhibit a high VPF release, which can be stimulated further by IL-15 + IL-12. To determine the specificity of the stimulatory effect, neutralizing anti-IL-15 and anti-IL-12 antibodies were preincubated with IL- 15 and IL-12 prior to the addition of responder cells, respectively. The antibodies completely inhibited the effects of IL-15 and IL-12. CONCLUSION: These results indicate that IL-15 plus IL-12 acted additively to augment VPF release. These biological interactions between IL-15 and IL-12 may be important in the pathophysiology of VPF in vitro.     

Studies of vascular permeability factor derived from T lymphocytes and inhibitory effect of plasma on its production in minimal change nephrotic syndrome

Peripheral T lymphocytes from patients with minimal change nephrotic syndrome (MCNS) and controls were treated for their ability to produce vascular permeability factors (VPF) without concanavalin A stimulation. In vitro cultures of T lymphocytes from active MCNS produced VPF in the supernatant, whereas T lymphocytes from inactive MCNS or normal subjects did not. Furthermore, the plasma from patients with active MCNS markedly inhibited VPF production when compared with plasma taken from inactive MCNS or fetal calf serum alone. However, the plasma from MCNS in neither the active nor the inactive stage had any direct blocking effect on VPF activity. These results seem to suggest that the plasma from patients with MCNS in the active stage inhibits VPF production, but does not neutralize T lymphocytes derived VPF activity.     

Tumor necrosis factor-α production from mononuclear cells in nephrotic syndrome

Tumor necrosis factor-alpha (TNF-alpha) levels in supernatant fluid from cultured peripheral blood mononuclear cells (PBMC) were measured by ELISA in 54 children with active non-inherited forms of primary nephrotic syndrome (PNS), 10 nephrotics in remission, and 10 healthy controls. Children with active PNS included 21 patients with steroid-sensitive (SS) minimal change nephrotic syndrome (MCNS), 5 patients with steroid-resistant (SR) MCNS, 11 with SR focal segmental glomerulosclerosis (FSGS), 6 patients with SS diffuse mesangial proliferation (DMP), 5 patients with SR DMP, and 6 patients with mesangiocapillary glomerulonephritis (MCGN). Patients with active PNS had elevated TNF-alpha production compared with controls. Remission was associated with normalization of TNF-alpha production. There was a positive correlation between TNF-alpha production and the degree of proteinuria ( r=0.34, P=0.013), mesangial hypercellularity ( r=0.42, P=0.028), and glomerulosclerosis ( r=0.46, P=0.001). By using ROC curve, TNF-alpha production greater or equal to a cut-off point of 50 pg/ml could be used to predict resistance to steroid therapy (predictability 93.2%). By discriminate analysis, TNF-alpha production could be used to discriminate between patients with SR MCNS, SR FSGS, and SR DMP (predictability 100%). In conclusion, TNF-alpha from cultured PBMC might be involved in the pathogenesis of proteinuria as well as the pathological changes that occur in non-inherited forms of PNS. TNF-alpha levels in PBMC culture could be used to predict the pathological type of PNS and the response of these patients to steroid therapy.     

Studies of glomerular permeability factor (GPF) in focal segmental glomerular sclerosis and the relationship between GPF and vascular permeability factor (VPF)

BACKGROUND: We previously demonstrated that the supernatants of cultured concanavalin-A (con-A) stimulated peripheral blood mononuclear cells (PBMC) from patients with minimal change nephrotic syndrome (MCNS) increased the urinary protein excretion in injected rats and suggested that PBMC released a factor, which we called glomerular permeability factor (GPF), changes in the glomerular permeability and thus resulted in proteinuria in MCNS. MATERIAL AND METHODS: In this study we investigated the GPF activity in focal segmental glomerular sclerosis (FGS) and other conditions of chronic glomerulonephritis (CGN), and also the relationship between GPF and vascular permeability factor (VPF). In experiment 1 the supernatants of the cultured con-A stimulated PBMC from patients with 10 FGS, 5 other CGN and 10 controls were tested regarding their ability to produce GPE The GPF activity was defined as positive when the 8-hour urinary protein excretion after the injection of the supernatant in Sprague-Dawley rats exceeded the mean value plus 2 standard deviations (M + 2 SD) of that before injection. RESULTS: Three out of 10 FGS patients and 1 membranous nephropathy patient out of the 5 other CGN patients were positive for GPF activity. In experiment 2 the relationship between GPF and VPF was analyzed using culture supernatants of PBMC from 10 nephrotic MCNS patients and 15 controls. The VPF activity was measured following the method developed by Ovary [1975]. All 7 cases that were positive for GPF activity were simultaneously positive for VPF activity. On the other hand, 16 cases that were positive for VPF activity were not always positive for GPF activity (7 cases were positive and 9 were negative for VPF activity). CONCLUSION: Experiments 1 and 2 thus suggested that GPF was not active in MCNS alone, but also in other CGN conditions and it was therefore not considered to be the same factor/substance(s) as VPF.     

Changing patterns in the histopathology of idiopathic nephrotic syndrome in children

BACKGROUND: It is widely accepted that minimal change nephrotic syndrome (MCNS) is the most common cause of nephrosis in children. Recent studies have demonstrated an increasing incidence of focal segmental glomerulosclerosis (FSGS) in adults. METHODS: To determine possible changes in the etiology of childhood nephrosis, the clinical charts of 152 pediatric patients diagnosed with idiopathic nephrotic syndrome between 1978 and 1997 were reviewed. Histopathological diagnosis was available in 105 patients. RESULTS: MCNS was present in 35% of all biopsies, whereas FSGS was observed in 31%. Even if we assume that all patients without a histological diagnosis had MCNS (presumptive MCNS), the total incidence of MCNS (biopsy proven + presumptive) in our population was only 55%. We observed a dramatic increase in the incidence of FSGS during recent years. Before 1990, FSGS was diagnosed in 23% of all renal biopsies but increased to 47% afterward (P = 0.02). This pattern was observed in all ethnic groups. In African Americans, there was a trend for an increase in the incidence of FSGS from 38% before 1990 to 69% after 1990. A similar trend was observed in Caucasians (from 20 to 45%) and Hispanics (from 8 to 33%) Hispanics had the highest incidence of MCNS (biopsy proven + presumptive: 73%), followed by Caucasians (53%) and African Americans (37%). The mean age for presentation of nephrotic syndrome in African Americans (8.0 +/- 0.9 years) was higher than in Caucasians (4.1 +/- 0.05) and Hispanics (3.3 +/- 0.5). CONCLUSIONS: Our study showed that the incidence of FSGS in children with idiopathic nephrotic syndrome has increased recently. Furthermore, in African American children. FSGS is the most common cause of nephrotic syndrome. These findings may have significant implications in the management of childhood nephrotic syndrome.     

C1q nephropathy and minimal change nephrotic syndrome

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.     

Immunoglobulin synthesis by peripheral blood mononuclear cells in minimal change nephrotic syndrome

The spontaneous and pokeweed mitogen (PWM)-induced immunoglobulin synthesizing activities of circulating mononuclear cells (MNC) from minimal change nephrotic syndrome systemic (MCNS) patients in relapse (N = 13) were compared with those of patients in remission (N = 9), patients with active systemic lupus erythematosus (SLE, N = 9), and healthy controls (N = 17). Cumulative amounts of IgM, IgG, and IgA secreted over a 12-day culture period were determined in a solid phase radioimmunoassay. Mean levels of spontaneous immunoglobulin production in control cultures did not exceed 370 ng/ml. In contrast unstimulated IgM, IgG, and IgA synthesis among MCNS patients in relapse averaged 588, 1258, and 2665 ng/ml, respectively. The majority of patients exhibited synthetic activities that equalled or exceeded those of patients with active SLE. Spontaneous immunoglobulin production declined by 80 to 97% in three patients restudied in stable remission. A fourth patient with frequent relapses maintained high rates of synthesis in remission as well as in relapse. PWM stimulation increased immunoglobulin production in patients in remission and controls but failed to increase or suppressed immunoglobulin secretion in SLE patients and patients in relapse. These results suggest that MNC from MCNS patients in relapse are reversibly activated in vivo.