Characterization of lysate from NK-92 cells and its potential use as an immunotherapeutic modality

Lysates from human cells represent biofluids that are used in the biotechnology field for a number of reasons such as biomarker identification and antibody detection. Lysate from human blood platelets is widely used in the clinical setting to control bleeding. We hypothesized that the lysate from the cytotoxic natural killer cell line NK-92® should contain perforin and proteolytic enzymes in addition to immunomodulatory cytokines, all of which have biological relevance and could be used for local treatment of cancer lesions. Here lysate from NK-92 (aNK™) cells, and its erIL-2 engineered variant haNK™ was obtained by repeat freeze/thawing. Immunoblot, ELISA and cytokine immunoassay analysis confirmed the presence of perforin and the full spectrum of granzymes, as well as of various chemokines and cytokines known to be expressed in NK-92 cells. Lysate from haNK cells displayed cytotoxic and anti-proliferative activity against human and canine cancer cell lines after only a 15-min exposure in vitro. Importantly, under the same conditions the lysate did not affect primary cells. Intra-tumor injection of haNK lysate into intradermal tumors of immunocompetent C57BL/6 mice provided tumor control in 40 % of treated animals. When re-challenged with the same tumor line several weeks after primary tumor clearance, no growth occurred indicating that intra-tumor administration of haNK lysate can generate a vaccine-like effect.