Phenotypic characterization of lymphokine-activated killer cells from human lymph node lymphocytes

We previously reported that lymphokine-activated killer (LAK) activity can be generated in human lymph node lymphocytes (LNL) at the same level as that in peripheral blood lymphocytes (PBL), despite the absence of active natural killer (NK) cells. In the present study, we investigated the surface phenotype of LNL-LAK cells by fractionation of lymphocytes, using a panning method. LNL isolated from lung cancer patients were cultured in the presence of recombinant interleukin 2 for 8 days and separated into T cells and non-T cells according to the expression of CD3 antigen. LAK effectors were enriched in the CD3- non-T cells. However, the CD3+ cells also mediated a low but substantial level of LAK activity, which was attributed to a CD8+ T-cell subset. Further investigation of the CD3- cells revealed that most of the CD3- effector cells expressed neither B-cell (CD20) nor NK-cell (CD16) markers. Precursors of this CD3-CD20-CD16- (null) population appeared to be also CD3-, CD20-, and CD16-. From these results, we would stress the significant contribution of CD3-CD20-CD16- null cells to the LAK phenomenon, which has not been focused on in PBL.