Differential Activation of Lymphokine‐activated Killer Cells with Different Surface Phenotypes by Cultivation with Recombinant Interleukin 2 or T‐cell Growth Factor in Gastric Cancer Patients

Fourteen days' culture of human peripheral blood lymphocytes (PBL) with recombinant interleukin 2 (rIL 2) or T cell growth factor (TCGF) results in the generation of lymphoklne‐activated killer (LAK) effector cells which have the unique property of lysing natural killer (NK)‐resistant human tumor cells, Daudi, as well as NK‐sensitive, K562 cells. LAK cells were generated from both normal and gastric cancer patients' PBL. However, LAK cell activities induced by rIL 2 or TCGF decreased with the progress of the tumor growth. In addition, TCGF‐induced LAK cell activities were found to be lower than the rIL 2‐indnced LAK cell activities. Different mechanisms may be involved in the decreases of the rIL 2‐induced and TCGF‐induced LAK cell activities. This study further demonstrates that the cell types involved are also heterogeneous, as determined by phenotypic characteristics. The LAK‐effector cell type was analyzed by two‐color flow cytometry. RIL 2‐induced LAK cells showed increased proportions of CD4(±)Leu 8(‐) and Leu 7(±)CD16(‐), and a decreased proportion of CD8(±)CD11(‐) cells, which are believed to be associated with killer T cell functions. In contrast, TCGF‐induced LAK cells revealed significantly increased proportions of CD8(±)CD11(‐)and CD4(±)Leu 8(‐) cells, and a decreased proportion of Leu 7(±)CD16(‐) cells. Thus, LAK cells with different surface phenotypes were induced by the cultivations with rIL 2 and with TCGF.