| Abstract: | Interleukin 2 (IL-2) can induce or enhance the cytotoxic activity of natural killer (NK) cells and lymphokine-activated killer (LAK) cells. The effects of fetal bovine serum (FBS) and human AB serum (HABS) on the IL-2-induced NK cell and LAK cell activities of large granular lymphocytes (LGL) were measured, respectively, against the NK-sensitive cell line K562 and the LAK-sensitive cell line Daudi. FBS and HABS were essentially equivalent in their effects on IL-2-dependent NK activity with prolonged culture. However, with prolonged incubation from 1 to 5 days of PBMC in the presence of IL-2, there was considerably less generation of LAK cell activity in FBS (Day 3: 5.3 +/- 3.4 LU/10(7) cells) compared to HABS (Day 3: 44.6 +/- 4.2 LU/10(7) cells) (P less than 0.05). These differences in IL-2-dependent LAK cell generation did not appear to be due to the lot of the FBS or to activating factors present in individual samples of HABS. Similarly, the suppressive effects of FBS could not be reversed with increasing concentrations of IL-2 ranging from 10 to 100 U/ml. Importantly, the presence of FBS in the cultures resulted in more cell death (15.9 +/- 5.6%) at 4 days of culture compared to HABS (1.8 +/- 1.0%) (P less than 0.05). These results suggest that FBS may inhibit generation of LAK effector cells, but not NK cells in cultures containing IL-2 and that the use of HABS as a culture supplement is preferable to FBS in studies of human LAK cell function. |
