John Seng Hooi Low

National Cancer Centre Singapore, Singapore

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Publications (4)9.33 Total impact

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    ABSTRACT: Human Vgamma2Vdelta2 T cells play important role in immunity to infection and cancer by monitoring self and foreign isoprenoid metabolites with their gammadelta T cell antigen receptors. Like CD4 and CD8 alphabeta T cells, adult peripheral Vgamma2Vdelta2 T cells represent a pool of heterogeneous cells with distinct functional capabilities. The aim of this study was to characterize the phenotypes and functions of various Vgamma2Vdelta2 T cell subsets in patients with nasopharyngeal carcinoma (NPC). We sought to develop a better understanding of the role of these cells during the course of disease and to facilitate the development of immunotherapeutic strategies against NPC. Although similar total percentages of peripheral blood Vgamma2Vdelta2 T cells were found in both NPC patients and normal donors, Vgamma2Vdelta2 T cells from NPC patients showed decreased cytotoxicity against tumor cells whereas Vgamma2Vdelta2 T cells from normal donors showed potent cytotoxicity. To investigate further, we compared the phenotypic characteristics of Vgamma2Vdelta2 T cells from 96 patients with NPC and 54 healthy controls. The fraction of late effector memory Vgamma2Vdelta2 T cells (T(EM RA)) was significantly increased in NPC patients with corresponding decreases in the fraction of early memory Vgamma2Vdelta2 T cells (T(CM)) compared with those in healthy controls. Moreover, T(EM RA) and T(CM) Vgamma2Vdelta2 cells from NPC patients produced significantly less IFN-gamma and TNF-alpha, potentially contributing to their impaired cytotoxicity. Radiotherapy or concurrent chemo-radiotherapy further increased the T(EM RA) Vgamma2Vdelta2 T cell population but did not correct the impaired production of IFN-gamma and TNF-alpha observed for T(EM RA) Vgamma2Vdelta2 T cells. We have identified distinct alterations in the Vgamma2Vdelta2 T cell subsets of patients with NPC. Moreover, the overall cellular effector function of gammadelta T cells is compromised in these patients. Our data suggest that the contribution of Vgamma2Vdelta2 T cells to control NPC may depend on the activation state and differentiation of these cells.
    Cancer Immunology and Immunotherapy 12/2008; 58(7):1095-107. · 3.64 Impact Factor
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    ABSTRACT: Endemic nasopharyngeal carcinoma (NPC) commonly metastasizes to the lungs, liver, and bones. This study aims to assess the efficacy of 4 distant metastasis staging modalities, namely (1) conventional work-up comprising chest X-ray, liver ultrasound, and skeletal scintigraphy, (2) CT of the thorax, abdomen, and skeletal scintigraphy, (3) (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), and (4) integrated FDG-PET/CT. Seventy-eight consecutive patients diagnosed with NPC were enrolled and followed up for a minimum of 6 months to confirm the staging at diagnosis. Six patients (7.7%) had distant metastases at diagnosis. The sensitivities and specificities of conventional work-up, combined CT and skeletal scintigraphy, FDG-PET, and FDG-PET/CT were 33.3%, 66.7%, 83.3%, and 83.3%; and 90.3%, 91.7%, 94.4%, and 97.2%, respectively. The corresponding accuracies were 85.9%, 89.7%, 93.6%, and 96.2%. FDG-PET/CT is the most sensitive, specific, and accurate modality for distant metastasis staging of endemic NPC.
    Head & Neck 11/2008; 31(3):346-54. · 2.83 Impact Factor
  • International Journal of Radiation Oncology Biology Physics - INT J RADIAT ONCOL BIOL PHYS. 01/2007; 69(3).
  • J S H Low, D M K Heng, J T S Wee
    Clinical Oncology 01/2005; 16(8):581-3. · 2.86 Impact Factor