Complement Factor H-Related 5-Hybrid Proteins Anchor Properdin and Activate Complement at Self-Surfaces.

C3 glomerulopathy (C3G) is a severe kidney disease for which no specific therapy exists. The causes of C3G are heterogeneous, and defective complement regulation is often linked to C3G pathogenesis. Copy number variations in the complement factor H-related (CFHR) gene cluster on chromosome 1q32 and CFHR5 mutant proteins associate with this disease. Here, we identified CFHR5 as a pattern recognition protein that binds to damaged human endothelial cell surfaces and to properdin, the human complement activator. We found the two N-terminal short consensus repeat domains of CFHR5 contact properdin and mediate dimer formation. These properdin-binding segments are duplicated in two mutant CFHR5 proteins, CFHR2-CFHR5Hyb from German patients with C3G and CFHR5Dup from Cypriot patients with C3G. Each of these mutated proteins assembled into large multimeric complexes and, compared to CFHR5, bound damaged human cell surfaces and properdin with greater intensity and exacerbated local complement activation. This enhanced surface binding and properdin recruitment was further evidenced in the mesangia of a transplanted and explanted kidney from a German patient with a CFHR2-CFHR5Hyb protein. Enhanced properdin staining correlated with local complement activation with C3b and C5b-9 deposition on the mesangial cell surface in vitro This gain of function in complement activation for two disease-associated CFHR5 mutants describes a new disease mechanism of C3G, which is relevant for defining appropriate treatment options for this disorder.

Batf-dependent Th17 cells critically regulate IL-23 driven colitis-associated colon cancer.

OBJECTIVES: IBDs have an increased risk for development of colorectal cancer (CRC). Here, we aimed at the characterisation of the functional role of Th17-associated transcription factors in sporadic and colitis-associated colon cancer in vivo. DESIGN: We used mice deficient or transgenic for the activating protein 1 family member basic leucine zipper transcription factor ATF-like (Batf) to evaluate the role of Th17 cells during sporadic and inflammation-induced colon carcinogenesis. We also studied the expression of Batf and RORγt in patients with IBD and CRC. RESULTS: Batf but not retinoic acid-related orphan receptor γt(RORγt) expression was significantly increased together with interleukin (IL) 23 expression in UC but not in Crohn's disease (CD) tissue samples. In CRC also Batf but not RORγt expression was increased and its expression correlated with the IL-23 and IL-23 receptor (IL-23R) expression. Finally, Batf but not RORγt was coexpressed with IL-17a, IL-23R and IL-6 within CRC-infiltrating CD4(+) T cells. Functional studies in mice revealed that Batf-dependent T cells are crucial regulators of sporadic and inflammation-induced CRC. Colitis-associated Batf(-/-) tumours lacked IL-17a(+)IL-23R(+)IL-6(+)CD4(+) T cells, hence displaying characteristics reminiscent of human CRC-infiltrating CD4(+) T cells. Strikingly, Batf(-/-) tumours contained low IL-23 but high IL-17a expression levels. Tumour formation and intratumoral IL-23 expression could be restored by administration of Hyper-IL-6 consisting of IL-6 and soluble IL-6 receptor. CONCLUSIONS: Batf-dependent IL-23R(+)IL-6(+)CD4(+) Th17 cells critically control IL-23 driven colitis-associated tumour formation and the progression of sporadic colon tumours. Batf-dependent IL-23R(+) T cells represent a potential future therapeutic target limiting CRC progression.

Identification and characterization of the specific murine NK cell subset supporting graft-versus-leukemia- and reducing graft-versus-host-effects.

Clinical studies investigating the impact of natural killer (NK) cells in allogeneic hematopoietic stem cell transplantation settings have yielded promising results. However, NK cells are a functionally and phenotypically heterogeneous population. Therefore, we addressed the functional relevance of specific NK cell subsets distinguished by expression of CD117, CD27 and CD11b surface markers in graft-versus-leukemia (GVL)-reaction and graft-versus-host-disease (GVHD). Our results clearly demonstrate that the subset of c-Kit-CD27-CD11b+ NK cells expressed multiple cytotoxic pathway genes and provided optimal graft-versus-leukemia-effects, while significantly reducing T cell proliferation induced by allogeneic dendritic cells. Furthermore, these NK cells migrated to inflamed intestinal tissues where graft-versus-host-colitis was efficiently mitigated. For the first time, we identified the c-Kit-CD27-CD11b+ NK cell population as the specific effector NK cell subset capable of significantly diminishing GVHD in fully mismatched bone marrow transplantation settings. In conclusion, the subset of c-Kit-CD27-CD11b+ NK cells not only supports GVL, but also plays a unique role in the protection against GVHD by migrating to the peripheral GVHD target organs where they exert efficient immunoregulatory activities. These new insights demonstrate the importance of selecting the optimal NK cell subset for cellular immunotherapy following allogeneic hematopoietic stem cell transplantation.

Vitamin D-dependent induction of cathelicidin in human macrophages results in cytotoxicity against high-grade B cell lymphoma.

Infiltration by macrophages represents a characteristic morphological hallmark in high-grade lymphatic malignancies such as Burkitt's lymphoma (BL). Although macrophages can, in principle, target neoplastic cells and mediate antibody-dependent cellular cytotoxicity (ADCC), tumor-associated macrophages (TAMs) regularly fail to exert direct cytotoxic functions. The underlying mechanisms responsible for this observation remain unclear. We demonstrate that inflammatory M1 macrophages kill proliferating high-grade B cell lymphoma cells by releasing the antimicrobial peptide cathelicidin in a vitamin D-dependent fashion. We show that cathelicidin directly induces cell death by targeting mitochondria of BL cells. In contrast, anti-inflammatory M2 macrophages and M2-like TAMs in BL exhibit an altered vitamin D metabolism, resulting in a reduced production of cathelicidin and consequently in inability to lyse BL cells. However, treatment of M2 macrophages with the bioactive form of vitamin D, 1,25D3, or a vitamin D receptor agonist effectively induces cathelicidin production and triggers tumoricidal activity against BL cells. Furthermore, rituximab-mediated cytotoxicity of vitamin D-treated M2 macrophages is cathelicidin-dependent. Finally, vitamin D treatment of 25-hydroxyvitamin D (25D)-deficient volunteers in vivo or primary TAMs in vitro improves rituximab-mediated ADCC against B cell lymphoma cells. These data indicate that activation of the vitamin D signaling pathway activates antitumor activity of TAMs and improves the efficacy of ADCC.

CLL-cells induce IDOhi CD14+HLA-DRlo myeloid-derived suppressor cells that inhibit T-cell responses and promote TRegs.

Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population that shares certain characteristics including an aberrant myeloid phenotype and the ability to suppress T cells. MDSCs have been predominantly studied in malignant diseases and findings suggest involvement in tumor-associated immune suppression. Chronic lymphocytic leukemia (CLL) is the leukemia with the highest incidence among adults. Immune defects occur already at early disease stages and impact the clinical course. We assessed presence, frequency, association to other immune parameters, and functional properties of circulating CD14(+) cells lacking HLA-DR expression (HLA-DR(lo)) in patients with untreated CLL. These monocytic cells represent one of the best-defined human MDSC subsets. Frequency of CD14(+)HLA-DR(lo) cells was significantly increased in CLL patients. Furthermore, MDSCs suppressed in vitro T-cell activation and induced suppressive regulatory T cells (TRegs). The MDSC-mediated modulation of T cells could be attributed to their increased indoleamine 2,3-dioxygenase (IDO) activity. CLL cells induced IDO(hi) MDSCs from healthy donor monocytes suggesting bidirectional crosstalk between CLL-cells, MDSCs, and TRegs. Overall, we identified a MDSC population that expands in CLL. The exact mechanisms responsible for such accumulation remain to be elucidated and it will be of interest to test whether antagonizing suppressive functions of CLL MDSCs could represent a mean for enhancing immune responses.

Critical role of spatial interaction between CD8⁺ and Foxp3⁺ cells in human gastric cancer: the distance matters.

PURPOSE: In various cancer types, an abundance of FoxP3(+) regulatory T cells (Treg) has been associated with an unfavorable outcome. Yet, the role of Treg on cancer immunity has been shown to be complex. In single cell marker technique, other tumor-infiltrating lymphocytes (TILs) such as cytotoxic CD8(+) T cells (CTL) also influenced prognosis. This study for the first time investigates the concurrent spatial distribution pattern of CD8(+) and FoxP3(+) TILs and their prognostic impact in human gastric cancer. MATERIALS AND METHODS: Tumor tissue microarrays of 50 patients with surgically treated adenocarcinoma of the cardia were studied. An immunohistochemical double staining of CD8(+) and FoxP3(+) TILs was performed. Cell counts and cell-to-cell distances in tumor epithelium and stroma were evaluated with image-processing software. Metastasis-free survival, no-evidence-of-disease survival, and overall survival were investigated (mean follow-up time 6.9 years). RESULTS: High intraepithelial infiltration of CD8(+) and FoxP3(+) TIL was associated with the improved 10-year metastasis-free survival (83 vs. 54%, p = 0.04 and 85 vs. 59%, p = 0.09, respectively). Considering cell-to-cell distance and comparing patients with functional (30-110 µm) versus nonfunctional distances of CD8(+) and FoxP3(+) TILs, 10-year survival rates differed between 89 and 55% (p = 0.009), respectively. CONCLUSION: Prognostic influence of tumor-infiltrating immune cells in gastric cancer critically depends on their cell-to-cell distance. FoxP3(+) TILs must be located within a distance between 30 and 110 µm of CD8(+) T cells to positively impact on prognosis.

[Rapid progressive glomerulonephritis as a nephrological emergency--case 8/2013]. / Die rapid-progressive Glomerulonephritis als nephrologischer Notfall--Fall 8/2013.

HISTORY AND ADMISSION FINDINGS: We report on a 53-year-old female patient who was admitted to hospital with fever, dyspnoea and arthralgias that was followed by diarrhoea and anuria. Upon respiratory deterioration she was referred to our hospital. INVESTIGATIONS: Urine analysis revealed an active urine sediment and kidney ultrasound showed hyperechoic renal parenchyma. Chest x-ray revealed widespread bilateral opacifications that were further investigated by bronchoscopy. A renal biopsy was performed due to an active urine sediment. DIAGNOSIS, TREATMENT AND COURSE: The patient suffered from pneumonia induced by pulmonary congestion and a newly acquired influenza infection. Histological examination of the kidney biopsy revealed an extracapillary proliferative IgA glomerulonephritis. After stabilization of the pulmonary situation and commencing hemodialysis, immunosuppressive therapy was started including cyclophosphamid. CONCLUSIONS: A rapid-progressive glomerulonephritis represents a nephrological emergency leading to acute kidney injury and dysfunction of other organs.

BK viremia and polyomavirus nephropathy in 352 kidney transplants; risk factors and potential role of mTOR inhibition.

BACKGROUND: Polyomavirus BK nephropathy (PyVAN) remains an important cause of early graft dysfunction and graft loss in kidney transplantation. METHODS: In this retrospective, single centre cohort study we studied the incidence and outcome of BK viral infection in 352 patients transplanted in 2008-2011. RESULTS: During follow-up viral replication was detected in 48 patients (13.6%); 22 patients (6.2%) had biopsy proven PyVAN.In multivariate logistic regression analyses risk factors for BK-viremia were lack of enrolment into randomized controlled trials (RCTs), biopsy proven acute rejections, cytomegaly virus (CMV) serostatus of both donor and recipient and previous transplantation.In patients without PyVAN reduction or switch of immunosuppression was associated with rapid viral clearance and stable graft function. In contrast, in most patients with PyVAN graft function deteriorated and 5 patients prematurely lost their allograft. Switch of immunosuppression to a low dose cyclosporine plus mTOR inhibitor based regimen in patients with PyVAN was safe, well tolerated and tended to be associated with a better short-term outcome in terms of graft function compared to reduction of existing immunosuppression alone. CONCLUSIONS: With the lack of licensed anti-polyoma viral drugs reduction or conversion of immunosuppression remains the mainstay of therapy in patients with PyVAN. The combination of low dose cyclosporine plus mTOR inhibition appears to be safe and warrants further investigation.

Cytotoxic effect of efavirenz is selective against cancer cells and associated with the cannabinoid system.

BACKGROUND: Recently, a regression of precancerous lesions in HIV-1-infected patients after initiation of HAART was reported. Nonnucleoside reverse transcriptase inhibitors (NNRTIs) as efavirenz (EFV) might be mediators of this effect, as they are known to have a cytotoxic effect on tumour cells. A potential mechanism involved in this effect may be the activation of the cannabinoid receptor to mediate tumour toxicity. METHODS: Several tumour-derived and fibroblast cell lines were studied. Cytotoxicity of EFV was evaluated by Annexin-Pi staining. The expression of the cannabinoid receptors CB1, CB2 and GPR55 was analysed by western blot, quantitative reverse transcriptase (qRT-PCR) and fluorescence activated cell sorting. The influence of the cannabinoid agonists and antagonists on the effects of EFV was investigated. Furthermore, the effect of EFV on the phosphorylation state of the growth factors Erk, Akt and the tumour suppressor protein p53 was tested. RESULTS: EFV revealed a selective cytotoxic effect on several tumour cell lines, whereas primary fibroblasts were not affected. The cytotoxic effect was associated with the expression of CB1. The combination of EFV with cannabinoid agonists showed an increase in toxicity. The phosphorylation state of Erk and Akt was not affected by EFV, whereas p53 showed an increased phosphorylation. CONCLUSION: EFV has a selective cytotoxic effect on several tumour cells. Furthermore, EFV led to an activating phosphorylation of the tumour suppressor protein p53 going in line with earlier reports that EFV may be antitumourigenic and a potential cytostatic drug. The observed synergistic effect with cannabinoid agonists implicates an involvement of the cannabinoid system.

Benign mesenchymal tumours and tumour-like lesions in end-stage renal disease.

AIMS: Mesenchymal neoplasms of the kidney are rare, and most represent sporadic angiomyolipomas. A few haemangiomas have been reported in end-stage renal disease (ESRD) but, to date, no study has focused on the frequency and morphological spectrum of mesenchymal lesions in ESRD. METHODS AND RESULTS: We evaluated retrospectively 90 nephrectomy specimens with ESRD. Haemangiomas were detected in eight cases (8.8%; six males and two females; mean age: 55 years); four were multifocal and four had concurrent renal epithelial neoplasms. Lesions involved the medulla (three), cortex (two) or both (three), and the size range was 1-25 mm (mean 4.8 mm). Histologically, all were capillary haemangiomas with an at least focally detectable spleen-like anastomosing pattern. All tumours stained positively for CD31 and FLI-1, but none expressed pankeratin (KL-1), podoplanin/D2-40, HHV8 or GLUT-1. Minute angiomyolipomas (mean size 2.3 mm) were detected in four patients (mean age 49.5 years). Tumour-like smooth muscle proliferations were seen surrounding muscular arteries (eight), occasionally admixed with fat extending from the renal sinus mimicking angiomyolipoma. No similar tumours were found in 105 control kidneys. CONCLUSIONS: Benign haemangiomas are not uncommon in ESRD, but may be under-recognized. They display distinctive morphology and should be distinguished from angiosarcomas and capillary-rich renal cell carcinomas.

Membranoproliferative glomerulonephritis complicating Waldenström's macroglobulinemia.

BACKGROUND: Lymphoproliferative disorders causing paraproteinemia can be associated with various kidney injuries including the deposition of monoclonal immunoglobulins (Ig). A known glomerular manifestation of Waldenström's macroglobulinemia is characterized by prominent intracapillary hyaline thrombi and lack of conspicuous glomerular proliferation. The present case was special in 2 aspects: 1. the diagnosis of glomerulonephritis was unexpected before renal biopsy, 2. the prominent glomerular proliferation paired with large intracapillary hyaline thrombi is uncommon in Waldenström's macroglobulinemia-associated glomerulonephritis. CASE PRESENTATION: A 73-year-old Caucasian woman with a long-standing history of rheumatoid arthritis and Waldenström's macroglobulinemia was admitted for acute renal failure (ARF), which initially was presumed to be the consequence of extrarenal causes. Proteinuria and hematuria were only mild. In renal core biopsy, a membranoproliferative glomerulonephritis (MPGN) and prominent intracapillary hyaline monoclonal IgM thrombi were found in addition to acute tubular necrosis. Of note, the patient's history was positive for purpuric skin changes, suspicious for cryoglobulinemia. However, serological tests for cryoglobulins were repeatedly negative. The ARF resolved before the start of immunomodulatory therapy for Waldenström's macroglobulinemia. CONCLUSION: The presence of MPGN with prominent hyaline thrombi in the context of Waldenström's macroglobulinemia is uncommon and can be oligosymptomatic. We discuss this case in the context of previous literature and classifications suggested for monoclonal Ig-related renal pathologies.

Radiochemotherapy fosters a favorable pattern of inflammatory cells in head and neck tumors.

The immune milieu in malignant tumors can influence the prognosis of patients. However, little is known about the effect the antitumoral therapy has on the inflammatory infiltrate. In head and neck squamous cell carcinoma we found evidence that a neoadjuvant radiochemotherapy could modulate the composition of the intratumoral inflammation into an anti-tumoral pattern.

Incidental monotypic (fat-poor) renal angiomyolipoma diagnosed by core needle biopsy.

We present the case of a 55-year-old patient with a history of chemotherapy and bone marrow transplantation because of acute myeloid leukaemia. An incidental 4 × 3 cm measuring renal mass was detected while performing a magnetic resonance imaging (MRI) for lumbago. The lesion was suspected to be either a renal cell carcinoma (RCC) or a leukemic infiltration. To decide about further treatment a percutaneous core needle biopsy was performed. Histology showed a monotypic angiomyolipoma, a relatively rare benign renal lesion. Interestingly, in cross-sectional imaging, angiomyolipoma was not taken into differential diagnostic account because of lack of a fatty component. Due to bleeding after biopsy the feeding artery of the tumor was occluded by microcoils. This case demonstrates the utility of biopsy of renal tumors, in particular when small tumor-like lesions are incidentally detected to decide about the right treatment and thereby avoiding nephrectomy.

Encapsulating peritoneal sclerosis - an overview.

Encapsulating peritoneal sclerosis (EPS) is a rare but life-threatening complication of peritoneal sclerosis (PD). In 2000, the International Society for Peritoneal Dialysis outlined diagnostic guidelines and a clinical definition of EPS. Over the intervening years, new evidence was published and several centers became more experienced managing patients with EPS. Although, further networking was initiated (European EPS Working Group), evidence regarding therapy and diagnosis of EPS is still lacking. Multicenter trials are needed to establish evidence regarding the management of EPS. Risk factors for EPS are identified and patients at risk should be monitored closely. In case of emerging signs of EPS, patients should be referred to an EPS-center before initiation of therapy. Morphology and immunohistochemistry will play a central role in the near future. Nowadays, most pathologists are not sophisticated in the pathology of peritoneal biopsies. Clear histological criteria are warranted. For the outcome of the patient, it is crucial that an EPS experienced surgeon conducts surgery.

Recurrent gross hematuria with positive family history of IgA nephropathy and an unexpected diagnosis.

A 12-year-old girl presented with recurrent gross hematuria over 3 months and regular findings in sonography of the urogenital tract. The first suspected diagnosis of familial IgA glomerulonephritis was excluded by kidney biopsy. After a further episode of gross hematuria leading to vesical tamponade, the patient received magnetic resonance imaging with angiography and urography, which was suspicious for a renal tumor. Consecutively, unilateral nephrectomy was performed and a nephroblastoma was diagnosed. This case demonstrates that even in grossly normal renal ultrasound, relapsing episodes of gross hematuria can be caused by renal tumor, and therefore in unclear situations, further diagnostic is necessary.

Inflammation in gastric adenocarcinoma of the cardia: how do EBV infection, Her2 amplification and cancer progression influence tumor-infiltrating lymphocytes?

Tumor-infiltrating lymphocytes (TILs) in gastric adenocarcinoma show a strong compartmentalization with high numbers of lymphocytes in the stroma and low intraepithelial lymphocyte counts. Our previous study has shown stromal regulatory T cells (Treg) to be associated with a beneficial outcome in intestinal type cancer of the cardia. We undertook the present study to further evaluate the immunogenic and inflammatory environment in intestinal-type gastric adenocarcinoma of the cardia. We assessed CXCR3 expression, Epstein-Barr virus (EBV) status, Her2/ERBB2 status and overexpression/amplification using tissue microarrays (immunohistochemistry and in situ hybridization) of 52 patients. The data were correlated to different TIL subset counts (CD3, CD8, GranzymeB, FoxP3 and CD20) and to infiltrating histiocytes (CD68) both in the tumor and the surrounding stromal tissue that were reported earlier. Her2/ERBB2 overexpression/amplification showed no correlation to tumor stage. Moreover, for the first time, we show here that Her2/ERBB2 overexpression/amplification has no correlation to overall or subset-specific TIL infiltration. EBV infection was seen in four cases and showed a strong association with intratumoral CD8(+) T cell infiltration as well as a moderate correlation to stromal CD8(+) T cell accumulation. Intratumoral CD8(+) T cell infiltration was significantly correlated to intratumoral FoxP3(+) Treg infiltration, and to a lesser extent, to stromal FoxP3(+) Treg counts. Stromal CXCR3(+) T cell infiltration showed an inverse correlation to T category. This highlights the importance of stromal immune processes for cancer growth and suggests a subversion of Th1 immunoresponse in cancer progression and underlines the important role of inflammation for early carcinogenesis.

Warburg phenotype in renal cell carcinoma: high expression of glucose-transporter 1 (GLUT-1) correlates with low CD8(+) T-cell infiltration in the tumor.

Many tumor cells are characterized by a dysregulated glucose metabolism associated with increased glycolysis in the presence of oxygen ("Warburg Effect"). Here, we analyzed for the first time a possible link between glucose metabolism and immune cell infiltration in renal cell carcinoma (RCC). RCC specimens revealed a highly significant increase in the expression of lactate dehydrogenase A (LDHA) and glucose-transporter 1 (GLUT-1) compared to the corresponding normal kidney tissue on mRNA level. Accordingly, tumor cell lines of different origin such as RCC, melanoma and hepatocellular carcinoma strongly expressed LDHA and GLUT-1 compared to their nonmalignant counterparts. In line with this finding, tumor cells secreted high amounts of lactate. High expression of GLUT-1 and LDH5, a tetramer of 4 LDHA subunits, was confirmed by tissue microarray analysis of 249 RCC specimens. Overall, 55/79 (69.6%) and 46/71 (64.7%) cases of clear cell carcinoma showed a constitutive, but heterogeneous expression of GLUT-1 and LDH5, respectively. The number of CD3(+), CD8(+) and FOXP3(+) T cells was significantly elevated in RCC lesions compared to normal kidney epithelium, but effector molecules such as granzyme B and perforin were decreased in tumor infiltrating T cells. Of interest, further analysis revealed an inverse correlation between GLUT-1 expression and the number of CD8(+) T cells in RCC lesions. Together, our data suggest that an accelerated glucose metabolism in RCC tissue is associated with a low infiltration of CD8(+) effector T cells. Targeting the glucose metabolism may represent an interesting tool to improve the efficacy of specific immunotherapeutic approaches in RCC.

[79-year-old patient with pulmorenal syndrome]. / Pulmorenales Syndrom bei einer 79-jährigen Patientin.

HISTORY AND ADMISSION FINDINGS: A 79-year-old female patient was referred with acute renal failure requiring haemodialysis and haemoptysis. INVESTIGATIONS: Kidney biopsy showed extracapillary proliferative glomerulonephritis with crescents in 7 from 15 glomeruli and sclerosis in the remaining. A computed tomography scan of the chest showed evidence of alveolar haemorrhage. Serologic testing revealed autoantibodies against the glomerular basement membrane (anti-GBM antibodies) and myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA). DIAGNOSIS, TREATMENT AND COURSE: The patient was diagnosed with goodpasture's disease and underwent immunosuppressive therapy including prednisolone, cyclophosphamide pulses and plasmapheresis, resulting in clearance of anti-GBM antibodies and discontinuation of haemoptysis. Renal function, however, did not recover and the patient remained on dialysis. CONCLUSIONS: Aggressive treatment including cyclophosphamide and plasma separation often ensures patient survival in goodpasture's disease, in most cases, however, renal function does not recover.

Characterisation of renal immune cell infiltrates in children with nephrotic syndrome.

There is increasing evidence that not only T cells but also B cells may play an important role in the pathogenesis of idiopathic nephrotic syndrome (NS). We have evaluated the infiltrating immune cells found in renal biopsies from 38 children with NS using immunohistochemistry techniques involving antibodies against T cells (CD3, CD4, CD8, FoxP3), B cells (CD20), macrophages (CD68) and follicular dendritic cells (CD21). Kidney biopsies with thin basement membrane disease were used as controls. We found higher numbers of interstitial CD3-positive T cells and macrophages in patients with focal segmental glomerulosclerosis (FSGS) than in those with minimal change glomerulopathy (MCGN) and in the controls, and significantly lower FoxP3-positive cells in patients with FSGS, MCGN and steroid-dependent NS than in the controls. Significantly higher numbers of glomerular B cells were found in FSGN patients than in MCGN patients and controls. Of note, in three patients who were later successfully treated with anti-CD20 antibody rituximab, the number of renal B cells was negligible in the preceding biopsy. In conclusion, the higher numbers of interstitial CD3-positive T cells in renal biopsies of pediatric patients with FSGS argue for a higher inflammatory activity. The significantly higher number of glomerular B cells in FSGS patients may indicate a particular pathogenetic role or epiphenomenon in this disease. However, patients with no interstitial or glomerular B cells could also benefit from rituximab treatment.