All trans retinoic acid enhances human LAK activity.

All trans retinoic acid has various effects on normal and malignant cells. Lymphokine-activated killer (LAK) activity can be derived from T lymphocytes and natural killer cells. This study shows that all trans retinoic acid significantly enhances this activity by increasing production of tumour necrosis factor and gamma interferon, which results in enhanced expression of the p55 part of the interleukin 2 receptor. This effect is dependent on the concentration of all trans retinoic acid and the length of time of culture.