Hsp70 Interacts with the TREM-1 Receptor Expressed on Monocytes and Thereby Stimulates Generation of Cytotoxic Lymphocytes Active against MHC-Negative Tumor Cells

The search for and analysis of new ligands for innate immunity receptors are of special significance for understanding the regulatory mechanisms of immune response. Here we show that the major heat shock protein 70 (Hsp70) can bind to and activate TREM-1, the innate immunity receptor expressed on monocytes. The Hsp70–TREM-1 interaction activates expression of TNFα and IFNγ mRNAs in monocytes and stimulates IL-2 secretion by PBMCs. Moreover, incubation of PBMCs with Hsp70 leads to an appearance of cytotoxic lymphocyte subpopulations active against the MHC-negative tumor cells. In addition, both the CD4+ T-lymphocytes and CD14+ monocytes are necessary for the Hsp70 signal transduction and a consequent activation of the cytotoxic lymphocytes. We believe that data presented in this study will broaden the views on the involvement of Hsp70 in the antitumor immunity