Induction of LAK cells in acute leukemia patients and kinetics of LAK activity in long term culture in vitro

Peripheral blood mononuclear cells（PBMNC）isolated from patients with acuteleukemia（AL）and from normal controls were cultured in a medium containing1000units/ml of recombinant interleukin-2（IL-2）.Marked LAK activity was induced onthe third culture day in the normal controls,with the highest cytotoxicity appearing be-tween day 3 and 5,whereas induction of LAK activity in the AL patients began on the5th day of culture,with a peak level appearing at day 15,showing that the peak ofLAK activity was significantly delayed in AL.LAK cells surface phenotyping tests showedthat CD8 and CD16 positive cells began to increase significantly from day 5 and reachedthe highest level at week 3,whereas CD4- subclass began to decrease at day 5 anddropped to the nadir at week 3,indicating that LAK activity was positively correlatedwith the proportion of CD8+ and CD16+ cells,but negatively with that of CD4+ cells.