Human heat shock protein 70 enhances tumor antigen presentation through complex formation and intracellular antigen delivery without innate immune signaling.
Heat shock proteins (HSPs) have shown promise for the optimization of protein-based vaccines because they can transfer exogenous antigens to dendritic cells and at the same time induce their maturation. Great care must be exercised in interpretating HSP-driven studies, as by-products linked to the recombinant generation of these proteins have been shown to mediate immunological effects. We generated highly purified human recombinant Hsp70 and demonstrated that it strongly enhances the cross-presentation of exogenous antigens resulting in better antigen-specific T cell stimulation. Augmentation of T cell stimulation was a direct function of the degree of complex formation between Hsp70 and peptides and correlated with improved antigen delivery to endosomal compartments. The Hsp70 activity was independent of TAP proteins and was not inhibited by exotoxin A or endosomal acidification. Consequently, Hsp70 enhanced cross-presentation of various antigenic sequences, even when they required different post-uptake processing and trafficking, as exemplified by the tumor antigens tyrosinase and Melan-A/MART-1. Furthermore, Hsp70 enhanced cross-presentation by different antigen-presenting cells (APCs), including dendritic cells and B cells. Importantly, enhanced cross-presentation and antigen-specific T cell activation were observed in the absence of innate signals transmitted by Hsp70. As Hsp70 supports the cross-presentation of different antigens and APCs and is inert to APC function, it may show efficacy in various settings of immune modulation, including induction of antigen-specific immunity or tolerance.
Institute of Molecular Immunology, GSF-National Research Center for Environment and Health Klinikum Grosshadern, Ludwig-Maximilians-University, Marchioninistrasse 25, 81377 Munich, Germany. henriette.bendz@gsf.de
Henriette
H
Bendz
Sibylle C
SC
Ruhland
Maya J
MJ
Pandya
Otmar
O
Hainzl
Stefan
S
Riegelsberger
Christoph
C
Braüchle
Matthias P
MP
Mayer
Johannes
J
Buchner
Rolf D
RD
Issels
Elfriede
E
Noessner
D017951:Antigen Presentation / Q000502:physiology*; D000951:Antigens, Neoplasm / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D045744:Cell Line, Tumor; D045142:Cross-Priming / Q000235:genetics / Q000276:immunology; D003713:Dendritic Cells / Q000276:immunology; D011992:Endosomes / Q000276:immunology; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000502:physiology; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D018613:Microscopy, Confocal; D018448:Models, Immunological; D010873:Pinocytosis / Q000276:immunology; D011994:Recombinant Proteins / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000951:Antigens, Neoplasm; D005456:Fluorescent Dyes; D018840:HSP70 Heat-Shock Proteins; D011994:Recombinant Proteins; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium