Augmentation of lymphokine-activated killer cell activity by lentinan.
Lymphokine-activated killer (LAK) activity stimulated by interleukin 2 (IL-2) and/or lentinan was examined in the peripheral blood of 9 healthy subjects and 7 cancer patients. After 4 and 8 days culture, LAK killer activity stimulated by IL-2 and lentinan against autologous tumor and K562 cells was greater than that stimulated by IL-2 alone. The optimal concentration of lentinan for the generation of killer cells ranged from 25-500 ng/ml, a level which can be achieved in vivo by the administration of clinical doses of this agent. The expression of CD25 antigen, the alpha chain of the IL-2 receptor on the activated killer cells was increased by lentinan. Thus it was shown that LAK cells stimulated with IL-2 plus lentinan had strong cytotoxicity and might be useful as effector cells for adoptive immunotherapy.