Methotrexate versus cyclophosphamide for remission maintenance in ANCA-associated vasculitis: A randomised trial.

OBJECTIVES: The treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is based on remission-induction and remission-maintenance. Methotrexate is a widely used immunosuppressant but only a few studies explored its role for maintenance in AAV. This trial investigated the efficacy and safety of methotrexate as maintenance therapy for AAV. METHODS: In this single-centre, open-label, randomised trial we compared methotrexate and cyclophosphamide for maintenance in AAV. We enrolled patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic granulomatosis with polyangiitis (EGPA), the latter with poor-prognosis factors and/or peripheral neuropathy. Remission was induced with cyclophosphamide. At remission, the patients were randomised to receive methotrexate or to continue with cyclophosphamide for 12 months; after treatment, they were followed for another 12 months. The primary end-point was relapse; secondary end-points included renal outcomes and treatment-related toxicity. RESULTS: Of the 94 enrolled patients, 23 were excluded during remission-induction or did not achieve remission; the remaining 71 were randomised to cyclophosphamide (n = 33) or methotrexate (n = 38). Relapse frequencies at months 12 and 24 after randomisation were not different between the two groups (p = 1.00 and 1.00). Relapse-free survival was also comparable (log-rank test p = 0.99). No differences in relapses were detected between the two treatments when GPA+MPA and EGPA were analysed separately. There were no differences in eGFR at months 12 and 24; proteinuria declined significantly (from diagnosis to month 24) only in the cyclophosphamide group (p = 0.0007). No significant differences in adverse event frequencies were observed. CONCLUSIONS: MTX may be effective and safe for remission-maintenance in AAV. TRIAL REGISTRATION: clinicaltrials.gov NCT00751517.

Association of Serum C3 Concentration and Histologic Signs of Thrombotic Microangiopathy with Outcomes among Patients with ANCA-Associated Renal Vasculitis.

BACKGROUND AND OBJECTIVES: Complement alternative pathway (cAP) activation has recently been recognized as a key pathogenic event in ANCA-associated vasculitis (AAV). cAP dysregulation is also a major determinant of thrombotic microangiopathies (TMA), which can in turn complicate AAV. We explored the prognostic significance of cAP activation and of histologic evidence of TMA in a cohort of patients with renal AAV. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We studied 46 patients with AAV diagnosed between January 1990 and December 2011 at the Nephrology Unit of Parma University Hospital; 30 of them had undergone renal biopsy. We analyzed serum levels of C3 (sC3) and C4 (sC4) and, for 19 patients who had frozen plasma, plasma Bb and C5b-9 levels. We also reviewed all kidney biopsy specimens, specifically searching for histologic signs of TMA, and performed immunofluorescence or immunohistochemistry for C3d, C4d, Bb and C5b-9. RESULTS: sC3 was below the lower limit of normal in 35% of the patients, whereas C4 was low in only 2%. Patients with low sC3 tended to be older (P=0.04) and to have lower eGFR at diagnosis (P=0.06). The median follow-up was 78 months (interquartile range, 18-135 months); 18 patients reached ESRD (10 of 14 and 8 of 26 in the low and normal sC3 groups, respectively). Death-censored renal survival was lower in the low sC3 group than in the normal sC3 group (log-rank test, P=0.01). Eight of the 30 patients who had undergone biopsy (27%) had histologic signs of TMA; these signs were more frequent in patients with low sC3 (5 of 10 versus 3 of 20; P=0.04). Notably, patients with histologic signs of TMA had a dramatically worse death-censored renal survival than patients without TMA (log-rank test, P=0.01), with ESRD occurring in 8 of 8 patients with TMA versus 8 of 22 patients without TMA. CONCLUSIONS: Low sC3 levels and histologic signs of TMA are associated with a poor renal prognosis in patients with AAV.

Chronic periaortitis with thoracic aorta and epiaortic artery involvement: a systemic large vessel vasculitis?

OBJECTIVE: Chronic periaortitis (CP) is a rare disease characterized by fibro-inflammatory tissue surrounding the abdominal aorta and the iliac arteries. Anecdotal reports have shown that CP may also involve other vascular districts, particularly the thoracic aorta. The aim of this study was to investigate the thoracic aorta and epiaortic artery involvement in CP. METHODS: Patients were eligible if they had undergone imaging studies assessing inflammatory involvement of the thoracic aorta and its major branches (e.g. contrast CT, MRI or PET-CT). We explored the patterns of thoracic vessel involvement and compared the clinical characteristics of patients with and without thoracic disease. Where available, we also reviewed the thoracic vascular/perivascular tissue biopsies. RESULTS: Of 153 CP patients seen between 1999 and 2012, 77 were eligible. Of these, 28 (36%) had thoracic involvement: 15 (54%) had thoracic periaortitis, with 7 also showing epiaortic artery involvement; 6 (21%) had periaortitis surrounding a thoracic aortic aneurysm, 2 of them with epiaortic artery involvement; 7 (25%) had a thoracic aortic aneurysm without periaortitis. Patients with thoracic disease were more frequently female (P = 0.01), were older (P = 0.001) and had a higher frequency of pain and constitutional symptoms (P = 0.02). Thoracic (peri)vascular biopsies revealed adventitial and peri-adventitial fibro-inflammatory patterns similar to those observed in abdominal CP. CONCLUSION: In about one-third of patients, CP also involves the thoracic aorta and the epiaortic arteries, which supports the hypothesis of a systemic inflammatory disease of the large arteries.

Sirolimus plus prednisone for Erdheim-Chester disease: an open-label trial.

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis, to whose pathogenesis neoplastic and immune-mediated mechanisms contribute. Mammalian target of rapamycin (mTOR)-inhibitors have antiproliferative and immunosuppressive properties. We tested in this study, the efficacy and safety of the mTOR-inhibitor sirolimus (SRL) plus prednisone (PDN) in patients with ECD. PDN was given initially at 0.75 mg/kg per day, tapered to 5 to 2.5 mg per day by month 6. Target SRL blood levels were 8 to 12 ng/mL. Treatment was continued for at least 24 months in patients who showed disease stabilization or improvement. Ten patients were enrolled; 8 achieved stable disease or objective responses, whereas 2 had disease progression. Responses were mainly observed at the following sites: retroperitoneum in 5/8 patients (62.5%), cardiovascular in 3/4 (75%), bone in 3/9 (33.3%), and central nervous system (CNS) in 1/3 (33.3%). The median follow-up was 29 months (interquartile range, 16.5-74.5); 2 patients died of progressive CNS disease and small-cell lung cancer, respectively. Treatment-related toxicity was mild. Using immunohistochemistry and immunofluorescence on ECD biopsies, we detected expression in foamy histiocytes of the phosphorylated forms of mTOR and of its downstream kinase p70S6K, which indicated mTOR pathway activation. In conclusion, SRL and PDN often induce objective responses or disease stabilization and may represent a valid treatment of ECD. The trial is registered at the Australia-New Zealand Clinical Trial Registry as #ACTRN12613001321730.

Association between idiopathic retroperitoneal fibrosis and autoimmune thyroiditis: a case-control study.

BACKGROUND: Idiopathic retroperitoneal fibrosis (IRF) is a rare disease often associated with autoimmune disorders. Whether IRF is associated with Hashimoto's thyroiditis (HT) is poorly understood and only addressed by case-reports. We evaluated the prevalence of HT in a large IRF cohort and in matched controls. METHODS: We studied 73 consecutive patients with new-onset IRF and 71 controls. The association between HT and IRF was cross-sectionally evaluated in a referral center. Longitudinally, thyroid function tests were also performed. Serum concentrations of FT4, TSH, and anti-thyroperoxidase antibodies (AbTPO) were evaluated together with thyroid ultrasound (US). Lymphocytic infiltrates were characterized in thyroid nodule fine needle aspirates (FNAB). In patients undergoing thyroidectomy, thyroid histology was also reviewed. RESULTS: A higher prevalence of AbTPO positivity (P<0.03) and US findings suggestive of autoimmune thyroiditis (US-AIT) (P<0.0001) were found in IRF patients compared to controls. In the logistic regression analysis, the risk of AbTPO-diagnosed HT and that of US-AIT was significantly higher in IRF patients than in controls (ORs, 3.56, 95% CI 1.48-8.59, P=0.004 and 4.74, 95% C.I., 2.34-9.61, P<0.0001 in AbTPO-diagnosed HT and US-AIT, respectively). Thyroid histology in IRF patients showed either classical or the fibrous variant of HT. At the end of the follow-up (median, 45 and 36 months in patients and controls, respectively), 25% of IRF patients and 3% of controls were receiving l-thyroxine. CONCLUSIONS: IRF patients have a higher risk of HT compared to controls. Thyroid function should be monitored in patients with IRF.

Eosinophilic granulomatosis with polyangiitis: an overview.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a multisystemic disorder, belonging to the small vessel anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, defined as an eosinophil-rich and necrotizing granulomatous inflammation often involving the respiratory tract, and necrotizing vasculitis predominantly affecting small to medium-sized vessels, associated with asthma and eosinophilia. EGPA pathogenesis is not well known: HLA-DRB1*04 and *07, HLA-DRB4 and IL10.2 haplotype of the IL-10 promoter gene are the most studied genetic determinants. Among the acquired pathogenetic factors, the exposure to different allergens, infections, vaccinations, drugs, and silica exposure have been involved. Eosinophils are the most characteristic cells in EGPA and different studies have demonstrated their role as effector and immunoregulatory cells. EGPA is considered as a disease with a prevalent activation of the Th-2 cellular-mediated inflammatory response and also humoral immunity plays an important role. A link between B and T inflammatory responses may explain different disease features. EGPA typically develops into three sequential phases: the allergic phase, distinguished by the occurrence of asthma, allergic rhinitis, and sinusitis, the eosinophilic phase, in which the main pathological finding is the eosinophilic organ infiltrations (e.g., lungs, heart, and gastrointestinal system), and the vasculitic phase, characterized by purpura, peripheral neuropathy, and constitutional symptoms. ANCA (especially pANCA anti-myeloperoxidase) are present in 40-60% of the patients. An elevation of IgG4 is frequently found. Corticosteroids and cyclophosphamide are classically used for remission induction, while azathioprine and methotrexate are the therapeutic options for remission maintenance. B-cell depletion with rituximab has shown promising results for remission induction.

Vascular endothelium as a target of immune response in renal transplant rejection.

This review of clinical and experimental studies aims at analyzing the interplay between graft endothelium and host immune system in renal transplantation, and how it affects the survival of the graft. Graft endothelium is indeed the first barrier between self and non-self that is encountered by host lymphocytes upon reperfusion of vascularized solid transplants. Endothelial cells (EC) express all the major sets of antigens (Ag) that elicit host immune response, and therefore represent a preferential target in organ rejection. Some of the Ag expressed by EC are target of the antibody-mediated response, such as the AB0 blood group system, the human leukocyte antigens (HLA), and MHC class I related chain A antigens (MICA) systems, and the endothelial cell-restricted Ag; for each of these systems, the mechanisms of interaction and damage of both preformed and de novo donor-specific antibodies are reviewed along with their impact on renal graft survival. Moreover, the rejection process can force injured EC to expose cryptic self-Ag, toward which an autoimmune response mounts, overlapping to the allo-immune response in the damaging of the graft. Not only are EC a passive target of the host immune response but also an active player in lymphocyte activation; therefore, their interaction with allogenic T-cells is analyzed on the basis of experimental in vitro and in vivo studies, according to the patterns of expression of the HLA class I and II and the co-stimulatory molecules specific for cytotoxic and helper T-cells. Finally, as the response that follows transplantation has proven to be not necessarily destructive, the factors that foster graft endothelium functioning in spite of rejection, and how they could be therapeutically harnessed to promote long-term graft acceptance, are described: accommodation that is resistance of EC to donor-specific antibodies, and endothelial cell ability to induce Foxp3+ regulatory T-cells, that are crucial mediators of tolerance.

Adjuvant low-dose interleukin-2 (IL-2) plus interferon-α (IFN-α) in operable renal cell carcinoma (RCC): a phase III, randomized, multicentre trial of the Italian Oncology Group for Clinical Research (GOIRC).

There is currently no standard therapy to reduce the recurrence rate after surgery for renal cell carcinoma (RCC). The aim of this study was to assess efficacy and safety of adjuvant treatment with low doses of interleukin-2 (IL-2)+interferon-α (IFN-α) in operable RCC. The patients were randomized 1:1 to receive a 4-week cycle of low-dose IL-2+IFN-α or observation after primary surgery for RCC. Treatment cycles were repeated every 4 months for the first 2 years and every 6 months for the subsequent 3 years. The primary endpoint was recurrence-free survival (RFS); safety; and overall survival (OS) were secondary endpoints. ClinicalTrials.gov registration number was NCT00502034. 303/310 randomized patients (156 in the immunotherapy arm and 154 in the observation group) were evaluable at the intention-to-treat analyses. The 2 arms were well balanced. At a median follow-up of 52 months (range, 12-151 mo), RFS, and OS were similar, with an estimated hazard ratio (HR) of 0.84 [95% confidence interval (CI), 0.54-1.31; P=0.44] and of 1.07 (95% CI, 0.64-1.79; P=0.79), respectively in the 2 groups. Unplanned, subgroup analysis showed a positive effect of the treatment for patients with age 60 years and younger, pN0, tumor grades 1-2, and pT3a stage. Among patients with the combined presence of ≥ 2 of these factors, immunotherapy had a positive effect on RFS (HR=0.44; 95% CI, 0.24-0.82; P ≤ 0.01), whereas patients with <2 factors in the treatment arm exhibited a significant poorer OS (HR=2.27; 95% CI, 1.03-5.03 P=0.037). Toxicity of immunotherapy was mild and limited to World Health Organization grade 1-2 in most cases. Adjuvant immunotherapy with IL-2+IFN-α showed no RFS or OS improvement in RCC patients who underwent radical surgery. The results of subset analysis here presented are only hypothesis generating.

Asbestos and smoking as risk factors for idiopathic retroperitoneal fibrosis: a case-control study.

BACKGROUND: Idiopathic retroperitoneal fibrosis (RPF) is a rare disease. Asbestos exposure has been proposed as a risk factor for idiopathic RPF. OBJECTIVE: To investigate the role of asbestos and other occupational agents (such as silica, metals, and organic solvents), as well as environmental agents (such as smoking), and their interactions as potential risk factors for idiopathic RPF. DESIGN: Case-control study. SETTING: National referral hospital for idiopathic RPF. PATIENTS: 90 patients with idiopathic RPF and 270 control participants matched for age, sex, and region of residency. MEASUREMENTS: Occupational history was obtained using structured questionnaires administered by blinded specialists in occupational medicine. Exposure to nonoccupational agents and presence of diseases that were potentially predisposing to idiopathic RPF were assessed through patient interviews and examination of medical records. RESULTS: A history of asbestos exposure was associated with idiopathic RPF (odds ratio [OR], 4.22 [95% CI, 2.14 to 8.33]). Both current smoking (OR, 3.21 [CI, 1.46 to 7.07]) and former smoking (OR, 2.93 [CI, 1.39 to 6.14]) were more prevalent among patients than among those who never smoked. A multiplicative effect was found between tobacco smoke and both occupational asbestos exposure (OR, 12.04 [CI, 4.32 to 38.28]) and extraoccupational asbestos exposure (OR, 8.42 [CI, 2.77 to 30.58]). LIMITATION: Retrospective, questionnaire-based assessment of occupational exposure. CONCLUSION: Exposure to asbestos and tobacco smoke resulted in strong risk factors for idiopathic RPF. Coexposure to asbestos and smoke had a multiplicative effect on risk compared with single exposure. PRIMARY FUNDING SOURCE: None.

Atypical haemolytic uraemic syndrome with underlying glomerulopathies. A case series and a review of the literature.

BACKGROUND: Primary or secondary glomerulonephritis has been anecdotally reported in association with atypical haemolytic uraemic syndrome (aHUS). We here report a series of six patients who developed aHUS and glomerulopathy, and review the literature on aHUS and glomerulonephritis. METHODS: Out of all patients diagnosed at our unit with biopsy-proven glomerular diseases between March 2007 and October 2011, selected cases developing aHUS during the follow-up are presented. The following tests were performed in all six patients: serum C3 and C4 levels, ADAMTS13 activity, CFH levels and anti-CFH autoantibodies and genetic screening for CFH, MCP, CFI, C3 and CFHR1-3 mutations and risk haplotypes associated with aHUS. RESULTS: Two hundred and forty-eight patients received a biopsy-proven diagnosis of glomerulopathy and were followed for a median of 31 months (range 2-58). Of these, six developed aHUS, within a median of 15 months (range 1-36) of their initial diagnosis of glomerulopathy. One of these patients had focal segmental glomerulosclerosis (FSGS), two membranoproliferative glomerulonephritis (MPGN) type I, one C3 glomerulonephritis and two systemic small vessel vasculitis [one granulomatosis with polyangiitis (Wegener's), one Henoch-Schoenlein purpura]. Five patients (one of them heterozygous for a CFH mutation) carried, in homo- or heterozygosity, the risk haplotype CFH-H3 (CFH tgtgt), previously described to be associated with aHUS, while another one patient was homozygous for the MCPggaac risk haplotype predisposing to aHUS when present on both alleles. CONCLUSIONS: Different types of glomerulopathies can be complicated by aHUS. Several mechanisms can contribute to this association, such as nephrotic-range proteinuria, mutations or aHUS-risk haplotypes involving genes encoding alternative complement regulatory proteins in some patients and inflammatory triggers associated with systemic immune-mediated diseases.

TLR-4 and VEGF polymorphisms in chronic periaortitis.

OBJECTIVE: Chronic periaortitis (CP) is a rare disease that is characterised by fibro-inflammatory tissue surrounding the abdominal aorta and has both non-aneurysmal (idiopathic retroperitoneal fibrosis [IRF]) and aneurysmal forms (inflammatory abdominal aortic aneurysm [IAAA]). We investigated whether toll-like receptor 4 (TLR-4) and vascular endothelial growth factor (VEGF) polymorphisms were associated with susceptibility to, and the clinical features of CP. METHODS: One hundred and two CP patients and 200 healthy controls were molecularly genotyped for TLR-4 gene polymorphism (+896 A/G) (rs4986790), VEGF mutations +936 C/T (rs3025039) and -634 C/G (rs2010963), and an 18 base pair (bp) insertion/deletion (I/D) polymorphism at -2549 of the VEGF promoter region. The patients were grouped on the basis of the type of CP (IRF or IAAA), and the presence or absence of established atherosclerotic disease (ischemic heart disease, cerebrovascular disease, and peripheral arterial disease). RESULTS: There were no significant differences in the distribution of the studied polymorphisms between the patients and controls. However, carriage of the +936 T allele was significantly more frequent in the patients with IRF than in those with IAAA (26.5% vs 5.3%; p = 0.046; OR 6.49 [95% CI 0.82-51.54]). There were significantly more carriers of the I allele among the patients with ureteral obstruction (83.8% vs 58.8%; p = 0.006; OR 3.63 [95% CI 1.42-9.28]) and those who received conservative treatment (48.5% vs 23.5%; p = 0.015; OR 3.06 [95% CI 1.22-7.721]) than among those without, and II homozygosity was significantly more frequent in the patients with deep vein thrombosis than in those without (30.4% vs 11.7%, p = 0.031; OR 3.31 [95% CI 1.07-10.21]). CONCLUSION: The VEGF +936 C/T polymorphism may be associated with an increased risk of developing the non-aneurysmal IRF form of CP. Carriers of the I allele and II homozygosity are respectively at increased risk of developing ureteral obstruction and deep vein thrombosis.

Incidence and prevalence of cancer in kidney transplantation waiting list patients: an Italian experience.

INTRODUCTION: Evaluation of kidney transplant candidates is based on strict exclusion of major pathologies, such as neoplastic disease. The aim of this study is to evaluate epidemiological and clinical impact of tumor disease in an Italian renal transplant waiting list and to propose a screening schedule for neoplastic detection.
 MATERIALS AND METHODS: We retrospectively observed data of patients enrolled on the Emilia-Romagna kidney transplant waiting list between 1st August 2008 and 31st December 2010, evaluating the different causes of getting out from the list, the histologic type and incidence of cancer and the correlation between cancer onset and clinical features. The ratio of observed to expected cancer numbers (standardized incidence ratio, SIR), was estimated. RESULTS: We observed 2345 patients; 1297 got out from the waiting list; 57 of them (4,4%) got out because the onset of tumor. The overall incidence rate of cancer was 1354.8 (x 100,000 person-year) (1045.9 person-year in patients awaiting for first transplant(FT), 1851.5 person-year in patients awaiting for second transplant(ST)). The overall prevalence of cancer was 2,43% (2.2% in FT, 3.4% in ST) with a SIR of 1.8; In our population the prevalence of cancers related to ESKD was 52.6% with a SIR of 15.8.
 CONCLUSION: Kidney transplant waiting list patients present a higher incidence and prevalence of cancer compared to general population; it could be important to evaluate them for ESKD related malignancies because of their high incidence.

Eotaxin/CCL11 in idiopathic retroperitoneal fibrosis.

BACKGROUND: Idiopathic retroperitoneal fibrosis (IRF) is a rare fibro-inflammatory disorder characterized by a periaortic tissue which often encases the ureters causing acute renal failure. IRF histology shows fibrosis and a chronic inflammatory infiltrate with frequent tissue eosinophilia. We assessed a panel of molecules promoting eosinophilia and fibrosis in IRF patients and performed an immunogenetic study. METHODS: Serum levels of eotaxin/CCL11, regulated and normal T-cell expressed and secreted (RANTES), granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-5, platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) were measured using a multiplex assay in 24 newly diagnosed, untreated IRF patients and 14 healthy controls. Retroperitoneal biopsies (available in 8/24 patients) were histologically evaluated to assess eosinophil infiltration, whereas mast cells (MCs) were identified by immunohistochemical analysis for human tryptase. Immunohistochemistry for eotaxin/CCL11 and its receptor CCR3 was also performed. Six single nucleotide polymorphisms (SNPs) within the CCL11 gene (rs6505403, rs1860184, rs4795896, rs17735961, rs16969415 and rs17809012) were investigated in 142 IRF patients and 214 healthy controls. RESULTS: Serum levels of eotaxin/CCL11 were higher in IRF patients than in controls (P = 0.009). Eotaxin/CCL11 drives tissue infiltration of eosinophils and MCs, which can promote fibrosis. Eosinophilic infiltration was prominent (>5 cells/hpf) in five (62.5%) cases, and abundant tryptase-positive MCs were found in all cases; notably, MCs were in a degranulating state. Immunohistochemistry showed that CCL11 was highly produced by infiltrating mononuclear cells and that its receptor CCR3 was expressed by infiltrating eosinophils, MCs, lymphocytes and fibroblasts. None of the tested CCL11 SNPs showed disease association, but the TTCCAT haplotype was significantly associated with IRF (P = 0.0005). CONCLUSIONS: These findings suggest that the eotaxin/CCL11-CCR3 axis is active in IRF and may contribute to its pathogenesis; the TTCCAT haplotype within the CCL11 gene is significantly associated with IRF.

Orofacial granulomatosis treated with low-level laser therapy: a case report.

OBJECTIVES: We report a case of orofacial granulomatosis successfully treated with low-level laser therapy (LLLT). STUDY DESIGN: LLLT was delivered through a diode laser device (Lasemar Eufoton, Trieste, Italy) with the use of a 4-cm defocalized lens and power of 1 W. Treatment was administered in sessions of 5 irradiations of 1 minute each, with a 1-minute interval between 2 subsequent irradiations (power density 0.08 W/cm(2); fluence/application: 4.8 J/cm(2); fluence/session: 24 J/cm(2)). Laser therapy was repeated 12 times (3 times per week). RESULTS: After 2 weeks of LLLT applications, the patient reported an improvement of symptomatology as well as a decrease of labial swelling. Complete healing was observed after 1 month. The patient was followed for 2 years. No recurrence of swelling was observed during the follow-up. CONCLUSIONS: Advantages of the LLLT approach include an absence of side effects, analgesic properties (usually reported after first application), and good patient compliance.

Changes in lymphocyte count induced by repeated cycles with low-dose interleukin-2 and interferon-α in 146 patients with renal cell carcinoma.

AIMS AND BACKGROUND: The exact mechanism by which recombinant interleukine-2 and interferon-α modulate the immunological response, inducing long-term responses in metastatic renal cell carcinoma, is still not clear. The aim of the study was to analyze the modifications in peripheral blood lymphocytes during cycles of low-dose immunotherapy as a marker of the biological response to the treatment in 146 patients with renal cell carcinoma (advanced and localized disease). METHODS AND STUDY DESIGN: Peripheral blood lymphocytes were evaluated before and after every cycle of treatment. RESULTS: We found a statistically significant overall difference between pre- and post-cycle values (mean increase of 39%). The differences between pre- and post-cycle lymphocyte counts for each cycle were significant. Also, the post-cycle lymphocyte count of each cycle remained higher than the baseline value. Furthermore, pre-cycle lymphocyte counts of each cycle were still higher than the baseline value, with no difference between a pre-cycle lymphocyte mean value and the other one (except that between the first and second cycle). From the end of each cycle, but before starting the next one, the absolute value of lymphocytes fell on the average by 15-30%, concurring with the fact that, even starting from pre-cycle values higher than baseline, the immune system remains sensitive to chronically repeated stimulation by immunotherapy. We also found that non-metastatic patients had a higher number of peripheral blood lymphocytes than metastatic patients, whereas the latter had a lower immune response to therapy. CONCLUSIONS: The results support the idea that "maintenance" immunotherapy may not develop resistance over time in terms of biological response and thus may have a role as chronic therapy in combination with other drugs such as target therapy. We suppose that the immune system of patients with metastases is in a state of relative impairment, resulting in less sensitivity to immunostimulating agents.