A new method for in vitro expansion of cytotoxic human CD3(-)CD56(+) natural killer cells

Adoptive transfer of immunocompetent cells may induce anti-tumor effects in vivo. However, a significant obstacle to the development of successful cel lular immunotherapy has been the availability of appropriate cytotoxic cell s. Among the immunologic effector cells that are considered mediators of an ti-tumor effects, those with the highest per-cell cytotoxic capacity expres s a natural killer (NK) cell phenotype, i.e., CD56(+)CD3(-). However, such cells are normally present only in low numbers in peripheral blood mononucl ear cells (PBMCs), lymphokine activated killer (LAK), and cytokine induced killer (CIK) cell preparations, To optimize the expansion of human NK cells , PBMCs were cultured in different serum free medium supplemented with mono clonal anti-CD3 antibodies and interleukin (IL)-2 at varying concentrations . By using Cellgro stem cell growth medium supplemented with 5% human serum and IL-2 (500 U/ml) cells expanded 193-fold (median, range 21-277) after 2 1 days, and contained 55% (median, range 7-92) CD3(-)CD56(+) cells. The rem aining cells were CD3(+) T cells, 22%. (median, range 2-68) of which co-exp ressed CD56. The expanded cell population lysed 26 to 45% of K562 targets i n a 1:1 effector to target ratio, signifying substantial cytotoxic efficacy . The described method is a simple and efficient way of expanding and enric hing human NK cells. We have termed these high-yield CD3(-)CD56(+) cells cy tokine-induced natural killer (CINK) cells. (C) American Society for Histoc ompatibility and Immunogenetics, 2001. Published by Elsevier Science Inc.