Viremic HIV Controllers Exhibit High Plasmacytoid Dendritic Cell-Reactive Opsonophagocytic IgG Antibody Responses against HIV-1 p24 Associated with Greater Antibody Isotype Diversification.
Identifying the mechanisms of natural control of HIV-1 infection could lead to novel approaches to prevent or cure HIV infection. Several studies have associated natural control of HIV-1 infection with IgG Abs against HIV-1 Gag proteins (e.g., p24) and/or production of IgG2 Abs against HIV-1 proteins. These Abs likely exert their effect by activating antiviral effector cell responses rather than virus neutralization. We hypothesized that an opsonophagocytic IgG Ab response against HIV-1 p24 that activates plasmacytoid dendritic cells (pDCs) through FcγRIIa would be associated with control of HIV and that this would be enhanced by Ab isotype diversification. Using the Gen2.2 pDC cell line, we demonstrated that pDC-reactive opsonophagocytic IgG Ab responses against HIV-1 p24 were higher in HIV controllers (HIV RNA < 2000 copies/ml) than noncontrollers (HIV RNA > 10,000 copies/ml), particularly in controllers with low but detectable viremia (HIV RNA 75-2000 copies/ml). Opsonophagocytic Ab responses correlated with plasma levels of IgG1 and IgG2 anti-HIV-1 p24 and, notably, correlated inversely with plasma HIV RNA levels in viremic HIV patients. Phagocytosis of these Abs was mediated via FcγRIIa. Isotype diversification (toward IgG2) was greatest in HIV controllers, and depletion of IgG2 from Ig preparations indicated that IgG2 Abs to HIV-1 p24 do not enhance phagocytosis, suggesting that they enhance other aspects of Ab function, such as Ag opsonization. Our findings emulate those for pDC-reactive opsonophagocytic Ab responses against coxsackie, picorna, and influenza viruses and demonstrate a previously undefined immune correlate of HIV-1 control that may be relevant to HIV vaccine development.
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia; Department of Clinical Immunology, Royal Perth Hospital and PathWest Laboratory Medicine, Perth, Western Australia 6000, Australia;
M Christian
MC
Tjiam
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia;
James P A
JP
Taylor
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia;
Mazmah A
MA
Morshidi
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia;
Lucy
L
Sariputra
School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia 6009, Australia;
Sally
S
Burrows
Division of Clinical Epidemiology, University of California, San Francisco, San Francisco, CA 94117;
Jeffrey N
JN
Martin
School of Medicine, University of California, San Francisco, San Francisco, CA 94117;
Steven G
SG
Deeks
School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia 6009, Australia; Centre for Asthma, Allergy and Respiratory Research, Lung Institute of Western Australia, Perth, Western Australia 6009, Australia; and.
Dino B A
DB
Tan
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia; Department of Microbiology and Infectious Diseases, Royal Perth Hospital and PathWest Laboratory Medicine, Perth, Western Australia 6000, Australia.
Silvia
S
Lee
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia;
Sonia
S
Fernandez
School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia 6009, Australia; Department of Clinical Immunology, Royal Perth Hospital and PathWest Laboratory Medicine, Perth, Western Australia 6000, Australia; martyn.french@uwa.edu.au.
Martyn A
MA
French
D016915:AIDS Vaccines / Q000276:immunology; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology*; D015483:HIV Antibodies / Q000097:blood / Q000276:immunology*; D016655:HIV Core Protein p24 / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology*; D010587:Phagocytosis / Q000276:immunology; D012367:RNA, Viral / Q000097:blood; D017452:Receptors, IgG / Q000276:immunology; D014766:Viremia / Q000276:immunology* / Q000821:virology
D016915:AIDS Vaccines; C080568:Fc gamma receptor IIA; D015483:HIV Antibodies; D016655:HIV Core Protein p24; D007074:Immunoglobulin G; D012367:RNA, Viral; D017452:Receptors, IgG