Inhibition of tumor growth in mice with severe combined immunodeficiency is mediated by heat shock protein 70 (Hsp70)-peptide-activated, CD94 positive natural killer cells.
Previously, we reported that the major stress-inducible heat shock protein 70 (Hsp70) acts as a recognition structure for natural killer (NK) cells, if localized on the cell surface of tumor cells. Incubation of purified NK cells with low-dose interleukin (IL)-2 (100 IU/mL) plus recombinant Hsp70-protein or the immunogenic 14-mer Hsp70-peptide TKDNNLLGRFELSG450-463, termed TKD (2 microg/mL), enhances the cytolytic activity against Hsp70 membrane-positive (CX+) but not against Hsp70-negative (CX-) tumor cells. Here, we show that the cytolytic activity against Hsp70-positive tumor cells is inducible by incubation of unseparated peripheral blood mononuclear cells (PBMNC) with low-dose IL-2 plus TKD. Cell sorting experiments revealed that within the PBMNC population CD94(+)/CD3(-) NK cells, and not CD94(-)/CD3(+) T cells, mediate the cytotoxic activity against Hsp70-positive tumor cells. The antitumoral effect of PBMNC stimulated either with IL-2 plus TKD or with IL-2 alone was assessed in tumor-bearing severe combined immunodeficiency/beige mice. A single intravenous (iv) injection of 40 x 10(6) IL-2 plus TKD-stimulated PBMNC (containing 5.2 x 10(6) NK cells) on day 4 results in a 60% reduction in tumor size, from 3.89 g to 1.56 g. In contrast, the adoptive transfer of the identical amount PBMNC stimulated with low-dose IL-2 only (containing 4.4 x 10(8) NK cells) reduces the tumor size only less than 10% (3.64 g). A phenotypic characterization of the excised tumors revealed that predominantly Hsp70-positive tumor cells were eliminated by TKD-activated PBMNC. Kinetic studies demonstrate that the in vivo cytolytic capacity of TKD-stimulated PBMNC is dependent on the effector to target cell ratio. An iv injection of effector cells on day 1 or 2 after tumor cell inoculation results in significantly smaller tumors (0.77 g or 0.89 g) on day 21 as compared with mice that were immunoreconstituted on day 4 or 8 (1.39 g or 2.23 g). The tumor size of nonimmunoreconstituted control animals was 3.55 g.
Moser
Christian
C
Department of Surgery, University Hospital Regensburg, Franz-Josef Strauss Allee 11, 93053 Regensburg, Germany.
Schmidbauer
Christin
C
Gürtler
Ulrich
U
Gross
Catharina
C
Gehrmann
Mathias
M
Thonigs
Gerald
G
Pfister
Karin
K
Multhoff
Gabriele
G
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D002455:Cell Division / Q000187:drug effects / Q000276:immunology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000276:immunology* / Q000494:pharmacology; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology*; D037181:Lectins, C-Type / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D051920:NK Cell Lectin-Like Receptor Subfamily D; D009369:Neoplasms / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology; D010446:Peptide Fragments / Q000494:pharmacology; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000494:pharmacology; D016511:Severe Combined Immunodeficiency / Q000150:complications* / Q000276:immunology* / Q000503:physiopathology; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000276:immunology / Q000637:transplantation
D015703:Antigens, CD; D018840:HSP70 Heat-Shock Proteins; D007376:Interleukin-2; C497869:KLRD1 protein, human; C497870:Klrd1 protein, mouse; D037181:Lectins, C-Type; D051920:NK Cell Lectin-Like Receptor Subfamily D; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins