Influence of Hsp70 and HLA-E on the killing of leukemic blasts by cytokine/Hsp70 peptide-activated human natural killer (NK) cells
- 153 Downloads
This study compared the effects of the human 70-kDa stress protein (Hsp70) peptide, TKDNNLLGRFELSG (TKD), proinflammatory cytokines, or a combination of both on the repertoire of receptors expressed by human natural killer (NK) cells and their capacity to kill human CX colon carcinoma cells, K562 erythroleukemic cells, and leukemic blasts from two patients with acute myelogenous leukemia. Low-dose interleukin (IL) 2/IL-15 and TKD increase the expression density of activatory (NKG2D, NKp30, NKp44, NKp46, CD94/NKG2C) and inhibitory (CD94/NKG2A) receptors on NK cells. Concomitantly, IL-2/TKD treatment enhances the cytotoxicity of NK cells (as reflected by their secretion of granzyme B) against Hsp70 membrane-positive and human leukocyte antigen (HLA)-E membrane-negative (Hsp70+/HLA-E−) CX+ and K562 cells. However, it had no effect on the responsiveness to Hsp70−/HLA-E− CX− cells over that induced by IL-2 alone. The cytotoxicity of IL-2/TKD-activated, purified NK cells and peripheral blood mononuclear cells against Hsp70+/HLA-E+ leukemic blasts was weaker than that against Hsp70+/HLA-E− K562 cells. Hsp70-blocking and HLA-E transfection experiments confirmed membrane-bound Hsp70 as being a recognition/activatory ligand for NK cells, as cytotoxicity was reduced by the presence of the anti-Hsp70 monoclonal antibody cmHsp70.2 and by inhibiting Hsp70 synthesis using short interference ribonucleic acid. HLA-E was confirmed as an inhibitory ligand, as the extent of NK cell-mediated lysis of K562 cell populations that had been transfected with HLA-ER or HLA-EG alleles was dependent on the proportion of HLA-E-expressing cells. These findings indicate that Hsp70 (as an activatory molecule) and HLA-E (as an inhibitory ligand) expression influence the susceptibility of leukemic cells to the cytolytic activities of cytokine/TKD-activated NK cells.
KeywordsHuman Natural killer cells Cell surface molecules Cytotoxicity Tumor immunity
The authors thank Professor Elisabeth Weiss (Institute of Anthropology and Human Genetics, University Ludwigs Maximilians Universität, Munich, Germany) for providing the HLA-E expressing K562 transfectants and Professor Eric Long (National Institute for Allergy and Infectious Diseases, USA) for constructive and helpful suggestions. This work was supported by EU-TRANSNET (MRTN 2004 512253), EU (LSHB-CT-2007-037703), the Bundesministerium für Bildung und Forschung (BMBF, project BioChance Plus), Deutsche Forschungsgemeinschaft (DFG, MU1238 7/2), and multimmune GmbH Munich, Germany.
- Cosman D, Mullberg J, Fanslow W, Armitage R, Chin W, Cassiano I (2000) The human cytomegalovirus (HCMV) glycoprotein, UL16, binds to the MHC class I-related protein, MICB/PERB11, and to two novel, MHC class I-related molecules. FASEB J 14:A1018Google Scholar
- Moser C, Schmidbauer C, Gurtler U, Gross C, Gehrmann M, Thonigs G, Pfister K, Multhoff G (2002) 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. Cell Stress Chaperones 7:365–373PubMedCrossRefGoogle Scholar
- Radons J, Stangl S, Multhoff G (2006) NK cell-based immunotherapies against tumors. Central Eur J Med 13:170–204Google Scholar