title: Monoclonal antibodies specific to human Δ42PD1: A novel immunoregulator potentially involved in HIV-1 and tumor pathogenesis.
abstract: We recently reported the identification of Δ42PD1, a novel alternatively spliced isoform of human PD1 that induces the production of pro-inflammatory cytokines from human peripheral blood mononuclear cells and enhances HIV-specific CD8(+) T cell immunity in mice when engineered in a fusion DNA vaccine. The detailed functional study of Δ42PD1, however, has been hampered due to the lack of a specific monoclonal antibody (mAb). In this study, we generated 2 high-affinity mAbs, clones CH34 (IgG2b) and CH101 (IgG1), from Δ42PD1-immunized mice. They recognize distinct domains of Δ42PD1 as determined by a yeast surface-displaying assay and ELISA. Moreover, they recognize native Δ42PD1 specifically, but not PD1, on cell surfaces by both flow cytometry and immunohistochemical assays. Δ42PD1 appeared to be expressed constitutively on healthy human CD14(+) monocytes, but its level of expression was down-regulated significantly during chronic HIV-1 infection. Since the level of Δ42PD1 expression on CD14(+) monocytes was negatively correlated with the CD4 count of untreated patients in a cross-sectional study, Δ42PD1 may play a role in HIV-1 pathogenesis. Lastly, when examining Δ42PD1 expression in human esophageal squamous-cell carcinoma tissues, we found high-level expression of Δ42PD1 on a subset of tumor-infiltrating T cells. Our study, therefore, resulted in 2 Δ42PD1-specific mAbs that can be used to further investigate Δ42PD1, a novel immune regulatory protein implicated in HIV-1 and tumor pathogenesis as well as other immune diseases.
authors.affiliation: a Center for Public Health Research; Medical School and Jiangsu Key Laboratory of Molecular Medicine; Nanjing University ; Nanjing , P.R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Cheng
authors.forename: Xian
authors.initials: X
authors.lastname: Tang
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Jie
authors.initials: J
authors.lastname: Peng
authors.forename: Kenji
authors.initials: K
authors.lastname: Nishiura
authors.forename: Allen Ka Loon
authors.initials: AK
authors.lastname: Cheung
authors.forename: Jia
authors.initials: J
authors.lastname: Guo
authors.forename: Xilin
authors.initials: X
authors.lastname: Wu
authors.forename: Hang Ying
authors.initials: HY
authors.lastname: Tang
authors.forename: Minghui
authors.initials: M
authors.lastname: An
authors.forename: Jingying
authors.initials: J
authors.lastname: Zhou
authors.forename: Ka Wai
authors.initials: KW
authors.lastname: Cheung
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Guan
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wu
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000276:immunology*; D000912:Antibodies, Neoplasm / Q000276:immunology*; D002294:Carcinoma, Squamous Cell / Q000276:immunology*; D004938:Esophageal Neoplasms / Q000276:immunology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D008297:Male; D051379:Mice; D009363:Neoplasm Proteins / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D061026:Programmed Cell Death 1 Receptor / Q000276:immunology*
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000912:Antibodies, Neoplasm; D007074:Immunoglobulin G; D009363:Neoplasm Proteins; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor
keywords: ART, antiretroviral therapy; ELISA, enzyme-linked immunosorbent assay; ESCC; ESCC, esophageal squamous cell carcinoma; FBS, fetal bovine serum; FSC, forward scatter; HIV-1; HIV-1, human immunodeficiency virus type 1; HRP, horseradish peroxidase; MFI, mean fluorescence intensity; OD450nm, optical density at 450nm; PBMCs, peripheral blood mononuclear cells; PD1; PD1, programmed cell death 1; RT, room temperature; SSC, side scatter; h, hour(s); mAb, monoclonal antibody; min, minute(s); monoclonal antibody; rpm, revolutions per minute; sPD1, soluble PD1; sec, second(s); sΔ42PD1, soluble Δ42PD1; tumor; Δ42PD1