Large-scale expansion of CD3⁺CD56⁺ lymphocytes capable of lysing autologous tumor cells with cytokine-rich supernatants

Abstract.

We have developed culture conditions for the efficient expansion of cytotoxic effector cells from peripheral blood mononuclear cells (PBMC) by the timed addition of cytokine-rich supernatants collected from allogeneic PBMC cultures stimulated with anti-CD3 monoclonal antibody (mAb) (allogeneic CD3 supernatants; ACD3S). These cytotoxic effectors belonged primarily to CD56⁺ natural killer (NK) cells, and the cell subset with the greatest cytotoxic activity was an otherwise rare population of CD3⁺CD56⁺ cells (NKT cells) that expand dramatically under these conditions. CD3⁺CD56⁺ cytotoxic effectors were generated from the PBMC of 16 patients with several types of cancer. The CD3⁺CD56⁺ cell subset expanded significantly and efficiently lysed NK- as well as lymphokine-activated killer (LAK)-sensitive targets. More importantly, ACD3S-activated CD3⁺CD56⁺ cells were capable of efficiently lysing autologous tumor cells including metastatic colorectal, ovarian, breast, lung and pancreatic tumor cells as well as melanoma cells. ACD3S-expanded CD3⁺CD56⁺ cells exhibited increased levels of cytoplasmic interleukin-2 (IL-2), tumor necrosis factor-α (TNF-α), gamma-interferon (IFN-γ) and perforin. CD3⁺CD56⁺ cell-mediated cytotoxicity was not restricted by major histocompatibility complex (MHC) gene products, since it was not blocked by anti-MHC class I mAb but was highly inhibited in the presence of CD2- and CD18-specific mAb. These data suggest that CD3⁺CD56⁺ cells expanded under the presence of ACD3S may be utilized in clinical protocols for cancer immunotherapy.