ABSTRACT
In vitro culture of peripheral blood lymphocytes (PBL) in interleukin-2 (IL-2) induces high levels of cytotoxic activity against both natural killer (NK)-sensitive and NK-resistant tumor target cells. If the patient's own LAK precursors could be activated by in vivo IL-2 treatment, such expensive and sometimes dangerous in vitro manipulations may not be necessary. Both the PBL count and the NK activity rebounded, and sometimes shot above the baseline, within 48 h after the injection. Intravenous injection of IL-2, either bolus or continuous infusion, caused immediate suppression of the numbers of circulating lymphocytes and the NK activity of recovered PBL.Repeated daily bolus or continuous infusion would sustain the high PBL counts and their elevated NK cytotoxicity. Interaction of the 75-kDa receptor with IL-2 alone is sufficient to augment NK activity in short-term treatment and induces lymphokine-activated killer activity in longer cultures.
