Lysosome-associated membrane protein-1-mediated targeting of the HIV-1 envelope protein to an endosomal/lysosomal compartment enhances its presentation to MHC class II-restricted T cells.
A subset of endogenously synthesized Ags can be processed for class II-restricted presentation, probably through multiple mechanisms. Processing of exogenous Ags for class II-restricted presentation appears to occur in unique endosomal processing compartments with lysosomal characteristics including the presence of the lysosomal membrane protein LAMP-1. Therefore, we attempted to enhance the efficiency of class II-restricted presentation of an endogenous Ag, the HIV-1 envelope (env) protein, by specifically targeting the Ag to class II processing compartments through the pathway followed by LAMP-1. Because the env protein associates tightly with CD4 shortly after synthesis, we first targeted the env protein using a chimeric CD4 protein consisting of the extracellular domain of CD4 and the transmembrane and cytoplasmic domains of LAMP-1. When co-expressed with this chimeric protein, the env protein was efficiently localized to lysosome-like compartments. Enhanced stimulation of env-specific CD4+ T cell clones by APC expressing the env protein and the CD4-LAMP-1 chimera was readily demonstrated in both cytotoxicity assays and proliferation assays. We also targeted the env protein directly as a chimeric protein consisting of the extracellular domain of the env protein and the transmembrane and cytoplasmic domains of LAMP-1. The proliferative response of env-specific CD4+ T cell clones to the env-LAMP-1 chimera was greatly enhanced compared with wild-type env protein, especially when limiting numbers of stimulator cells were used. The enhanced stimulatory capacity of APC expressing LAMP-1-targeted Ags has important implications for vaccine design.
Rowell
J F
JF
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Ruff
A L
AL
Guarnieri
F G
FG
Staveley-O'Carroll
K
K
Lin
X
X
Tang
J
J
August
J T
JT
Siliciano
R F
RF
D017951:Antigen Presentation; D015703:Antigens, CD; D001483:Base Sequence; D015704:CD4 Antigens / Q000502:physiology; D011992:Endosomes / Q000378:metabolism*; D015699:HIV Envelope Protein gp120 / Q000378:metabolism*; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D006801:Humans; D051907:Lysosomal Membrane Proteins; D008247:Lysosomes / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000502:physiology*; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000276:immunology*
D015703:Antigens, CD; D015704:CD4 Antigens; D015699:HIV Envelope Protein gp120; D000949:Histocompatibility Antigens Class II; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins