Natural killer cells play a key role in the antitumor immunity generated by chaperone‐rich cell lysate vaccination

Tumor derived chaperone‐rich cell lysate (CRCL) when isolated from tumor tissues is a potent vaccine that contains at least 4 of the highly immunogenic heat shock proteins (HSP) such as HSP70, HSP90, glucose related protein 94 and calreticulin. We have previously documented that CRCL provides both a source of tumor antigens and danger signals triggering dendritic cell (DC) activation. Immunization with tumor derived CRCL elicits tumor‐specific T cell responses leading to tumor regression. In the current study, we further dissect the mechanisms by which CRCL simulates the immune system, and demonstrate that natural killer (NK) cells are required for effective antitumor effects to take place. Our results illustrate that CRCL directly stimulates proinflammatory cytokine and chemokine production by NK cells, which may lead to activation and recruitment of macrophages at the tumor site. Thus, this report provides further insight into the function of CRCL as an immunostimulant against cancer. © 2006 Wiley‐Liss, Inc.