A Phase II, Multicenter, Randomized, Placebo-Controlled Study of Benralizumab, a Humanized Anti-IL-5R Alpha Monoclonal Antibody, in Patients With Eosinophilic Chronic Rhinosinusitis.

BACKGROUND: Strong eosinophil infiltration in chronic rhinosinusitis with nasal polyp (CRSwNP) is highly associated with recalcitrance and higher nasal polyp recurrence rate after surgery. The prevalence of eosinophilic CRSwNP (ECRS) is increasing in Asian countries including Japan. Benralizumab is a humanized anti-IL-5R alpha monoclonal antibody that depletes eosinophils by antibody-dependent cell-mediated cytotoxicity. OBJECTIVE: To assess the efficacy and safety of benralizumab in patients with ECRS. METHODS: This phase II, randomized, double-blind, placebo-controlled study was conducted in Japan. Patients were randomized 1:2:2 to placebo, a single administration of benralizumab 30 mg, or benralizumab 30 mg every 4 weeks (q4w) for a total of three doses. The primary endpoint was the change in nasal polyp score from baseline at Week 12. RESULTS: Overall, 56 patients were enrolled (placebo, n = 11; benralizumab single dose, n = 22; benralizumab q4w, n = 23). Although the mean total nasal polyp score began to decrease after the initiation of benralizumab treatment, there were no statistically significant differences in change in nasal polyp score from baseline at Week 12 between benralizumab and placebo (placebo, -0.5 ± 0.8; benralizumab single, -0.3 ± 0.8; benralizumab q4w, -0.5 ± 1.5). Post-hoc analysis showed that the administration of benralizumab decreased nasal polyp scores ≥2 points in 42.2% of ECRS patients and that patients with high blood eosinophil levels had a greater tendency to respond to benralizumab treatment. The safety profile was similar to that in previous studies and no unexpected adverse events were noted. CONCLUSION: Although benralizumab did not meet the primary efficacy endpoint, reductions of nasal polyp scores were seen in the benralizumab group compared with the placebo group over the whole study period, especially in patients with high levels of blood eosinophils.

HDAC inhibitors suppress the proliferation, migration and invasiveness of human head and neck squamous cell carcinoma cells via p63­mediated tight junction molecules and p21­mediated growth arrest.

In human head and neck squamous cell carcinoma (HNSCC), the invasion and metastatic properties of cancer cells are promoted by junctional adhesion molecule­A (JAM­A) and claudin­1; these are epithelial tight junction molecules regulated by histone deacetylases (HDACs) and transcription factor p63. HDAC expression is reportedly upregulated in HNSCC, and HDAC inhibitors suppress cancer cell proliferation by initiating proliferative arrest or apoptosis. However, little is known of the anti­cancer mechanisms of HDAC inhibitors in HNSCC. Thus, in the present study, the HNSCC Detroit 562 cell line and primary cultured HNSCC cells were treated with HDAC inhibitors to investigate their effects in HNSCC. Higher expression of p63, HDAC1, JAM­A and claudin­1 was observed in HNSCC tissues compared with the adjacent dysplastic regions. In Detroit 562 cells, treatment with trichostatin A (TSA), an inhibitor of HDAC1 and 6, downregulated the expression of p63, JAM­A and claudin­1, and upregulated that of acetylated tubulin; conversely, p63 knockdown resulted in the downregulation of JAM­A and claudin­1. Collectively, inhibiting HDAC suppressed the migration and invasiveness of cancer cells. In addition, treatment with TSA suppressed cancer cell proliferation via G2/M arrest, as well as upregulating p21 and downregulating cyclin D1 expression. TSA also downregulated the expression of epidermal growth factor receptor (EGFR) and phospho­ERK1/2. p63 knockdown and treatment with an EGFR inhibitor induced G1 arrest and downregulated EGFR and phospho­ERK1/2 levels, respectively. HDAC inhibition also suppressed the migration and invasiveness of primary cultured HNSCC cells. Collectively, the results of the present study indicate that HDAC inhibitors suppress the proliferation, migration and invasiveness of HNSCC by downregulating the p63­mediated tight junction molecules JAM­A and claudin­1, and inducing p63 or p21­mediated growth arrest.

Telefitting of Nucleus Cochlear Implants: A Feasibility Study.

Purpose This study aims to describe the recommended equipment and procedures required for successful telefitting, based on our experience, document and evaluate patient satisfaction with telefitting, and assess its clinical usefulness and address the existing issues. Method Twenty (seven children and 13 adults) individuals who lived far from cochlear implant (CI) centers and who were Nucleus CI users underwent conventional face-to-face fitting and telefitting. We examined the participants' subjective satisfaction and cost and time saved with the telefitting experience. Results The telefitting sessions lasted for an average of 16 min. Majority of the participants responded positively to the telefitting experience. Eighty percent (16/20) of the participants were satisfied with the new procedure, and 85% of them agreed to use telefitting again. Conclusions The results of our feasibility study suggest that telefitting was well received by CI users and is a viable alternative to local MAPping, even in young children with CIs. Although there are some limitations in terms of adaptability, telefitting could be an effective means of delivering CI service to remote locations.

Role of RANK-L as a potential inducer of ILC2-mediated type 2 inflammation in chronic rhinosinusitis with nasal polyps.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by type 2 inflammation with accumulation of activated group 2 innate lymphoid cells (ILC2s) and elevation of thymic stromal lymphopoietin (TSLP). A member of the TNF superfamily (TNFSF), TNFSF15, is known to induce the production of type 2 cytokines in ILC2s. Although ILC2s have been implicated in CRSwNP, the presence and role of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP has not been elucidated. Here, we investigate the involvement of TNFSFs in ILC2-mediated type 2 inflammation in CRSwNP. We found that receptor activator of NF-κB (RANK) ligand (RANK-L (TNFSF11)) was significantly elevated in nasal polyps (NPs), and that the receptor of RANK-L, RANK, was expressed on ILC2s in human peripheral blood and NPs. An agonistic antibody against RANK induced production of type 2 cytokines in human ILC2s, and TSLP significantly enhanced this reaction. The membrane-bound RANK-L was detected mainly on CD45 + immune cells, including TH2 cells in NPs. The co-culture of NP-derived ILC2s and TH2 cells significantly enhanced production of type 2 cytokines, and anti-RANK-L monoclonal antibody suppressed this enhancement. In conclusion, RANK-L, together with TSLP, may play an inductive role in the ILC2-mediated type 2 inflammation in CRSwNP.

Rho-kinase and PKCα Inhibition Induces Primary Cilia Elongation and Alters the Behavior of Undifferentiated and Differentiated Temperature-sensitive Mouse Cochlear Cells.

Primary cilia, regulated via distinct signal transduction pathways, play crucial roles in various cellular behaviors. However, the full regulatory mechanism involved in primary cilia development during cellular differentiation is not fully understood, particularly for the sensory hair cells of the mammalian cochlea. In this study, we investigated the effects of the Rho-kinase inhibitor Y27632 and PKCα inhibitor GF109203X on primary cilia-related cell behavior in undifferentiated and differentiated temperature-sensitive mouse cochlear precursor hair cells (the conditionally immortalized US/VOT-E36 cell line). Our results indicate that treatment with Y27632 or GF109203X induced primary cilia elongation and tubulin acetylation in both differentiated and undifferentiated cells. Concomitant with cilia elongation, Y27632 treatment also increased Hook2 and cyclinD1 expression, while only Hook2 expression was increased after treatment with GF109203X. In the undifferentiated cells, we observed an increase in the number of S and G2/M stage cells and a decrease of G1 cells after treatment with Y27632, while the opposite was observed after treatment with GF109203X. Finally, while both treatments decreased oxidative stress, only treatment with Y27632, not GF109203X, induced cell cycle-dependent cell proliferation and cell migration.

Induction of airway progenitor cells via p63 and KLF11 by Rho-kinase inhibitor Y27632 in hTERT-human nasal epithelial cells.

Rho-kinase inhibitor Y27632, which is a factor in conditional reprogramming culture, induces airway progenitor clone formation. To investigate whether Y27632 enhances airway progenitor cells in nasal epithelium, primary cultures of HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs) were treated with Y27632. In TERT-HNECs treated with Y27632 for 5 days, upregulation of p63, gap junction molecules Cx26, Cx30, Cx43, cytochrome P450 enzymes CYP2C9, CYP2C18, CYP39A1, CYP4B1, CYP2G1P, CYP4Z1, and KLF families KLF10 and KLF11 were observed compared to the control. Downregulation of tight junction molecules claudin-4, -7, and -23 was observed. Circumfential submembrane F-actin was also induced. The functions of gap junctional intercellular communication (GJIC) and the epithelial barrier were upregulated. Knockdown of p63 by siRNAs of TAp63 or ΔNp63 inhibited Cx26, Cx43 and CYP2C18, and induced claudin-1, and -4. Knockdown of KLF11 prevented p63 expression and enhancement of the epithelial barrier function by Y27632. In nasal mucosal tissues from patients with allergic rhinitis (AR), localized alteration of p63, KLF11, RhoA, Cx30 and claudin-4 was observed. Treatment with Y27632 in long-term culture induced airway progenitor cells via KLF11 in p63-positive human nasal epithelium. Airway progenitor cells of nasal epithelium induced by Y27632 is important in understanding upper airway disease-specific characteristics.

IL-10+ T follicular regulatory cells are associated with the pathogenesis of IgG4-related disease.

IgG4-related disease (IgG4-RD) is a chronic fibroinflammatory disease characterized by elevation of serum IgG4 level as well as infiltration of IgG4+ plasma cells in various affected organs. The etiology of IgG4-RD is still not fully understood. Since IgG4-RD is more prevalent in the elderly, aging in itself is considered to be an important risk factor of IgG4-RD. However, the relationship between the pathogenesis of IgG4-RD and immunosenescence remains unknown. To clarify age-related features underlying IgG4-RD, we focused on T follicular regulatory (Tfr) cells, which share forkhead box P3 with regulatory T cells, since the percentage of Tfr cells is known to depend on age. Studies of blood specimens from patients with IgG4-RD and from healthy volunteers demonstrated a marked elevation of circulating Tfr (cTfr) cells in patients with IgG4-RD. Moreover, the percentage of cTfr cells was significantly correlated with various clinical parameters including the level of serum IgG4 and the number of involved organs in IgG4-RD patients. The percentages of tonsillar and blood Tfr cells were increased with aging in healthy volunteers, whereas the suppressive effect of cTfr cells on B cell function in elderly subjects was impaired in comparison with that in young subjects due to a defect in the production of a regulatory cytokine, IL-10. Given that the number of IL-10-producing cTfr cells in IgG4-RD patients was markedly increased compared with that in healthy elderly subjects, these findings suggest that an abnormal aging process of Tfr cells may be related to the pathogenesis of IgG4-RD.

Interleukin 5-producing ST2+ memory Th2 cells in IgG4-related dacryoadenitis and sialadenitis.

Objectives: Immunoglobulin (Ig) G4-related disease (IgG4-RD) is often complicated by allergic disorders. This study was conducted to investigate the mechanism of type 2 helper T-inflammation (Th2-inflammation) in IgG4-related dacryoadenitis and sialadenitis (IgG4-DS). Methods: We separated and analyzed the proportion of growth stimulation expressed gene 2 (ST2)+ memory Th2 cells among the peripheral blood mononuclear cells by flow cytometry in cases with IgG4-DS and healthy individuals. Finally, we identified the role of ST2+ memory Th2 cells in the involved tissues. Results: The proportion of circulating ST2+ memory Th2 cells was much higher in the patients with IgG4-DS than in the healthy controls. Abundant infiltration of ST2+ memory Th2 cells was detected in the involved salivary glands and lymph nodes, and these cells produced interleukin-5. Conclusion: We demonstrated that there is an increase of interleukin-5 producing ST2+ memory Th2 cells in the involved tissues in IgG4-DS. This subset of cells is considered to be an important player in inducing the inflammatory Th2 environment characteristic of IgG4-DS.

Mechanism of fibrogenesis in submandibular glands in patients with IgG4-RD.

The aim of this study was to investigate the mechanisms driving fibrosis in the submandibular glands (SMG) of patients with IgG4-related disease (IgG4-RD). Immunohistochemistry showed that many fibroblast-like cells expressing IL-6, IL-18, TSLP, IL-33, and MMP1 were present in SMG from the affected patients. SMG fibroblasts were derived from patients with or without IgG4-RD and were cultured in vitro. Expression of IL-6, IL-18, TSLP, IL-33 and MMP1, the secretion of IL-6 and G2/M phase were upregulated in the fibroblasts from the affected patients. By treatment with inflammatory cytokines IL-1ß, TNFα or TGF-ß after treatment with or without the NF-κB inhibitor curcumin, curucumin blocked the production and secretion of IL-6 upregulated by IL-1ß, TNFα, or TNFα/TGF-ß in all fibroblasts. Wnt1-inducible signaling protein 1 (WISP1), which can enhance fibroblasts proliferation, was also more abundantly expressed in affected fibroblasts, while treatment with IL-6 induced WISP1, treatment with WISP1 increased the G2/M phase, and curucumin inhibited WISP1 induced by TNFα/TGF-ß in unaffected fibroblasts. IL-33 in affected fibroblasts was induced by IL-1ß, TNFα, or TNFα/TGF-ß, while the effect of IL-1ß or TNFα/TGF-ß was blocked by curcumin. These results suggest fibrosis in the SMG of affected patients is closely linked to the proliferation of fibroblasts following induction of IL-6 and WISP1 by inflammatory cytokines. The Th2 cytokines TSLP and IL-33 are also upregulated in affected SMG, and thus may cause chronic inflammation and IgG4 accumulation.

Influence of PD-L1 expression in immune cells on the response to radiation therapy in patients with oropharyngeal squamous cell carcinoma.

BACKGROUND AND PURPOSE: To investigate influences of proteins involved with tumor immunity on outcomes of radiotherapy for oropharyngeal squamous cell carcinoma (OPSCC). MATERIAL AND METHODS: We performed immunohistochemical staining to examine expressions of p16 and proteins involved with tumor immunity in 92 OPSCC patients treated with radiotherapy. RESULTS: Patients with abundant infiltrating CD8-positive cells had the significantly better overall survival (OS) rate than patients with fewer CD8-positive cells (p = 0.026). Patients with higher PD-L1 expression in tumor cells (TC 1-3) had a better outcome than those with low PD-L1 expression in tumor cells (TC 0) for both OS (p = 0.019) and progression-free survival (PFS) rate (p = 0.032). Patients with high PD-L1 expression in infiltrating immune cells (IC 3) showed significantly better OS (p = 0.009) and PFS (p = 0.011) than those with low PD-L1 expression (IC 0-2). Patients with p16-negative and IC 3 showed similar OS to patients with p16-positive and IC 0-2. P16-positive tumors had a significantly higher CD8-positive cell infiltration and PD-L1 expression in tumor cells than p16-negative tumors. CONCLUSIONS: In addition to tumor p16 expression, PD-L1 expression in TC and IC can be useful for predicting the response of OPSCC to radiotherapy.

Guanylate binding protein-1-mediated epithelial barrier in human salivary gland duct epithelium.

Guanylate-binding protein-1 (GBP-1) is an interferon-inducible large GTPase involved in the epithelial barrier at tight junctions. To investigate the role of GBP-1 in the epithelial barrier, primary human salivary gland duct epithelial cells were treated with the the proinflammatory cytokines IFNγ, IL-1ß, TNFα and the growth factor TGF-ß. Treatment with IFNγ, IL-1ß, or TNFα markedly enhanced GBP-1 and the epithelial barrier function, and induced not only CLDN-7 but also the tricellular tight junction molecule lipolysis-stimulated lipoprotein receptor (LSR). Knockdown of GBP-1 by its siRNA induced endocytosis of tight junction molecules, and prevented the increases of CLDN-7 and LSR with the upregulation of the epithelial barrier function induced by treatment with IFNγ or TNFα. Treatment with a PKCα inhibitor induced expression of GBP-1, CLDN-7 and LSR and enhanced the epithelial barrier function. In almost intact salivary gland ducts from patients with IgG4-related disease (IgG4-RD) indicated significant infiltration of IgG-positive plasma cells, expression of GBP-1, CLDN-7 and LSR was increased. These findings indicated that GBP-1 might play a crucial role in barrier function of normal human salivary gland duct epithelium and perform a preventive role in the duct epithelium of IgG4-RD disease.

Stage classification of IgG4-related dacryoadenitis and sialadenitis by the serum cytokine environment.

OBJECTIVES: Patients with immunoglobulin-G4 related disease (IgG4-RD) diagnosed according to the comprehensive diagnostic criteria (CDC) show varied therapeutic responses and prognoses. We assumed that there are clinical stages in IgG4-RD and have verified it using serum cytokine levels in the groups classified by lesion distribution. METHODS: Definite IgG4-related dacryoadenitis and sialadenitis (IgG4-DS) cases were divided according to the CDC for IgG4-RD into 11 cases with focal type and 30 cases with systemic type. The levels of serum interleukin (IL)-4, IL-5, IL-6, IL-10, IL-13, IL-15, IL-21, interferon (IFN)-α, IFN-γ, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-ß1, and monocyte chemotactic protein (MCP)-1 were measured in healthy controls, allergic patients, probable IgG4-RD cases, and focal and systemic type cases. The cytokine environment was analyzed in each group. The 52 definite IgG4-RD cases were next classified into four groups with cluster analysis in terms of therapeutic responses and prognosis. The relationships between each cytokine level and therapeutic responses were also analyzed. RESULTS: Both serum IL-5 and IFN-α concentrations were very low in healthy controls, but they increased in the allergic cases, probable cases, and focal and systemic type cases. The level of serum IL-5 was significantly higher in definite cases than in healthy controls. The serum IL-5 level was also significantly increased in the groups with a poor prognosis than in the good prognosis group. CONCLUSION: These results suggest that there are clinical stages in IgG4-RD, and serum IL-5 play roles in the pathogenesis of IgG4-RD.

Circulating PD-1+CXCR5-CD4+ T cells underlying the immunological mechanisms of IgG4-related disease.

OBJECTIVE: The aim was to study the pathological role of lymphocytes with a peripheral T helper-cell-like phenotype (PD-1+CXCR5-CD4+) in IgG4-related disease (IgG4-RD). METHODS: PD-1+CXCR5-CD4+ T cells in the blood of patients with IgG4-RD (n = 53), patients with SS (n = 16) and healthy volunteers (n = 34) as controls were analysed by flow cytometry. Correlations between results obtained by flow cytometry and clinical parameters relevant to IgG4-RD were also analysed. RESULTS: The percentage and absolute number of PD-1+CXCR5- cells within total CD4+ T cells in IgG4-RD patients were significantly increased compared with those in healthy volunteers. Further analysis showed that there were marked positive correlations of the percentage of PD-1+CXCR5-CD4+ T cells with the serum level of IgG4 and the number of organs involved. Interestingly, granzyme A (GZMA)+ cells were enriched in PD-1+CXCR5-CD4+ T cells, and the percentage and absolute number of GZMA+PD-1+CXCR5-CD4+ T cells were significantly elevated in IgG4-RD patients. Although no obvious change was observed in the percentage of total CD4+ T cells, the percentage and absolute number of PD-1+CXCR5-CD4+ T cells decreased in accordance with a reduction of serum IgG4 level after treatment with glucocorticoids. CONCLUSION: In IgG4-RD, circulating CD4+ T-cell populations were composed of PD-1+CXCR5- cells, and the ratios of these cells were correlated with clinical manifestations of IgG4-RD. Further analysis of GZMA+PD-1+CXCR5-CD4+ T cells might lead to a deeper understanding of the pathogenesis of ectopic lymphoid follicles and the persistent inflammation in IgG4-RD.

Predicting therapeutic response in IgG4-related disease based on cluster analysis.

To bring the clinical practice of immunoglobulin (Ig)G4-related disease (IgG4-RD) close to personalized medicine, we classified the patient groups and clarified the therapeutic responses of each group. A total of 147 patients enrolled in our registry were classified into four groups by cluster analysis with the software. The therapeutic responses and prognosis of each group were examined. The cluster analysis classified the subjects into four groups: Cluster 1, patients who presented with prominent hypergammaglobulinemia, elevated levels of serum IgG4, and hypocomplementemia; Cluster 2, patients who presented with eosinophilia, elevated concentrations of serum IgG, IgG4, and IgE, and in whom CRP tended to be positive; Cluster 3, patients with younger onset and serum levels of IgG, IgG4, and IgE and peripheral eosinophil counts lower than the other clusters; and Cluster 4, patients with elder onset and low peripheral eosinophil counts. The amounts of glucocorticoid for maintenance treatment were from 5 to 7 mg/d in all groups, but the amounts were significantly greater in Cluster 1 (patients with hypergammaglobulinemia, elevated levels of serum IgG4, and hypocomplementemia) than in Cluster 4 (elder onset patients, relatively low concentrations of peripheral eosinophils). With regard to the use of immunosuppressants and the relapse rate, there were high frequencies in Cluster 1 and Cluster 3 (younger onset patients who presented with mild elevations of serum IgG and IgG4). On the other hand, Cluster 4 showed a low rate of relapse and often could discontinue steroids. The present results suggest that personalized medicine could be provided in IgG4-RD by classifying patients based on their clinical features.

Clinical utility of 18 F-fluorodeoxyglucose/positron emission tomography in diagnosis of immunoglobulin G4-related sclerosing sialadenitis.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate the utility of 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for accurately diagnosing immunoglobulin G4-related sclerosing sialadenitis (IgG4-SS). STUDY DESIGN: Retrospective cohort study. METHODS: We reviewed the records of 64 patients with IgG4-SS (35 male and 29 female patients) and 10 patients with clinically suspected IgG4-SS. Pathological diagnoses of patients clinically suspected with IgG4-SS included four cases of malignant lymphoma, one case of multicentric Castleman disease, one case of Sjögren's syndrome, and four cases of sialadenitis. All patients underwent submandibular gland (SMG) biopsies and baseline FDG-PET/CT evaluation. Clinical, serological, pathological, and PET/CT findings were analyzed. We also investigated maximum standardized uptake values (SUVmax) in the salivary glands of 15 patients with malignant disease of the salivary glands during the same period. RESULTS: Increased FDG uptake in the SMG and parotid gland was found in 63 (98%) and 23 (35%) patients with IgG4-SS, respectively. FDG uptake of the bilateral SMG and unilateral SMG was recorded in 57 patients (89%) and six patients (9%), respectively. Mean SUVmax in patients with malignant disease of the salivary glands was significantly higher than that in patients with IgG4-SS (P = .035). We defined a positive test for IgG4-SS diagnosis as high SMG FDG uptake and serum IgG4 level ≥135 mg/dL, resulting in a sensitivity, specificity, and accuracy of 96.9%, 90.0%, and 86.4%, respectively. CONCLUSIONS: FDG-PET/CT findings in combination with serological and clinical findings may have the capacity to diagnose IgG4-SS and lead to less-invasive biopsy procedures. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1120-1125, 2018.

Clinical and Prognostic Analysis of Hypopharyngeal Squamous Cell Carcinoma with Synchronous and Metachronous Multiple Malignancies.

BACKGROUND/AIM: To analyze the clinical features and prevalence of synchronous and metachronous second primary malignancies (SPMs) in patients with hypopharyngeal squamous cell carcinoma (HSCC), their associated risk factors, and cause-specific mortality. PATIENTS AND METHODS: We retrospectively reviewed 136 patients treated with curative intent at our hospital. Statistical analyses were performed to determine factors predictive of SPM and cause-specific mortality. RESULTS: Sixty-three of 136 patients (46.3%) developed SPM; of these, 41 (30.1%) and 42 (30.9%) had synchronous and metachronous SPMs, respectively, with patient overlap. The most common site of synchronous and metachronous SPMs was the oesophagus (65.8% and 24.4%, respectively); the corresponding overall survival rates were 34.1% and 66.5%, respectively. Furthermore, heavy drinking was significantly correlated with synchronous SPM (p<0.001). CONCLUSION: Oesophageal cancer surveillance is recommended for patients with HSCC, especially heavy drinkers. Our findings may help identify and properly manage HSCC patients at high risk of SPMs.

Evaluation of consistency in quantification of gene copy number by real-time reverse transcription quantitative polymerase chain reaction and virus titer by plaque-forming assay for human respiratory syncytial virus.

The plaque-forming assay is the standard technique for determining viral titer, and a critical measurement for investigating viral replication. However, this assay is highly dependent on experimental technique and conditions. In the case of human respiratory syncytial virus (RSV) in particular, it can be difficult to objectively confirm the accuracy of plaque-forming assay because the plaques made by RSV are often small and unclear. In recent studies, RT-qPCR methods have emerged as a supportive procedure for assessment of viral titer, yielding highly sensitive and reproducible results. In this report, we compare the viral replication, as determined by plaque-forming assay, and the copy numbers of RSV genes NS1, NS2, N, and F, as determined by RT-qPCR. Two real-time PCR systems, SYBR Green and TaqMan probe, gave highly similar results for measurement of copy numbers of RSV N genes of virus subgroups A. We determined the RSV gene copy numbers in the culture cell supernatant and cell lysate measured at various multiplicities of infection. We found that copy number of the RSV N gene in the culture supernatant and cell lysate was highly correlated with plaque-forming units. In conclusion, RT-qPCR measurement of RSV gene copy number was highly dependent on viral titer, and the detailed comparison between each gene copy number and virus titer should be useful and supportive in confirming RSV plaque-forming assay and virus dynamics. The technique may also be used to estimate the amount of RSV present in clinical specimens.