10044 Background: We have previously reported that vaccination with heat shock protein 70 (HSP70) induced natural killer (NK) cell activity in patients with chronic myelogenous leukemia (CML). The underlying mechanism is unclear. Methods: HSP70 was purified from the peripheral blood mononuclear cells. CD56+ NK cells were enriched by magnetic sorting after staining PBMCs with anti-CD56 monoclonal antibody. Dendritic cells (DCs) were derived from peripheral blood monocytes after culture in the presence of IL-4 and GM-CSF. NK activation was measured by the IFNgamma ELISPOT assay. Results: Unexpectedly, HSP70 of autologous, allogeneic as well as xenogeneic origin was found to stimulate IFNgamma production from peripheral blood mononuclear cells of CML patients as well as normal subjects. Further studies demonstrated that the activity of HSP70 was dependent on both NK cells and DCs. HSP70 did not induce significant IFNgamma production from either NK cells or DCs alone. Mechanistically, we found that HSP70-mediated DC-NK cell crosstalk required cell-cell contact, which could be inhibited completely by neutralizing antibody against NK activating receptor NKG2D. The significance of NKG2D was further corroborated by the finding that HSP70 induced the expression of an NKG2D ligand, the MHC class I chain-related protein A (MICA), on DCs; HSP70-augmented IFNgamma release was abrogated by antibody against MICA. Conclusions: Thus HSP70 may serve as a critical link between NK and DCs in mounting immune responses against infections, cancers and self-antigens. Our novel findings support further studies in the development of HSP70-based vaccines against human malignancies. Acknowledgement: Z.L. is a clinical scholar of the Leukemia and Lymphoma Society. No significant financial relationships to disclose.
Autophagy and Heat Shock Protein 70 Expression During Acute Heat Stress in Isosmotic and Hyperosmotic Conditions in Peripheral Blood Mononuclear Cells from Young Adults: Preliminary Data
