Properties of mouse lymphokine activated-killer (LAK) cells were examined by using polyclonal and monoclonal LAK cells. To identify cell types of LAK cells, LAK cells were induced from various mouse lymphoid tissues and examined for the surface phenotypes by means of negative selection and FACS analysis. Irrespective of the cell sources, LAK cells expressed Thy 1 and lymphocyte function-associated antigen 1 (LFA-1) as common markers but the expressions of asialoGM1 and Lyt antigens were different from their cell sources. The induction of LAK cells from spleen cells was more frequent in asialoGM1+, Lyt 2- (natural killer (NK) cell type) cells than in asialoGM1-, Lyt 2+ (T cell type). To further assess the properties of LAK cells, we established LAK cell clones from LAK cell lines induced from C57BL/6 mouse spleen cells. Although these clones expressed the similar phenotypes to the parent LAK cells, Lyt 2 was expressed in a limited portion of the clones. All clones were found to express T3 and T cell receptor (TcR)-alpha beta, and rearrangement patterns of TcR-beta were the same among the clones derived from the same parent cell line but different in clones derived from different cell lines as determined by using C beta 1 and J beta 2 probes. The molecules responsible for LAK-target cell binding were examined by using killer blocking antibody (KBA) (anti-LFA-1) monoclonal antibody (mAb) and anti-idiotypic polyclonal antibody (Id) to KBA.(ABSTRACT TRUNCATED AT 250 WORDS)