AbstractCD3+CD8+cells, purified from peripheral blood T cells by depletion of CD4+lymphocytes, were tested for their cytotoxic activity against K‐562 or HL‐60 cells. Freshly prepared cells had no cytotoxic function, but upon exposure to recombinant interleukin 2 (rIL 2)in vitrothey acquired a lymphokine‐activated killer (LAK) activity. Fractionation of CD3+CD8+cells into CD11b+and CD11b−cells demonstrated that all the cells with the potential of developing LAK cell functions were within the CD8+CD11b+subset. These cells lacked natural killer cell markers such as CD16 or NKH1, but a proportion of them stained for Leu‐7. Furthermore, they expressed the α/β chains, but not the γ/δ chains, of the T cell receptor, as could be determined by staining with the appropriate monoclonal antibodies. CD8+CD11b+cells had a large granular lymphocyte morphology, as shown by both cytochemical and electron microscopy analyses. They proliferated in response to IL 2in vitroand developed cytotoxic functions against a number of natural killer resistant targets. Their response to phytohemagglutinin or pokeweed mitogen was very weak or absent. By contrast, CD8+CD11b−cells failed to generate LAK cells in response to rIL 2, did not show a large granular lymphocyte morphology, but responded vigorously to phytohemagglutinin or pokeweed mitogen.Purified CD8+CD11b+cells were cloned by limiting dilution in the presence of rIL 2. The observed cloning efficiency of 19 ± 0.3 indicates that a fraction of the cells only could respond to IL 2. Furthermore, only 50 of the clones obtained had a LAK cell function. These data show that CD8+CD11b+cells represent a heterogeneous cell population. Nevertheless this cell subset probably represents the major source of LAK cell progenitors within the cir
展开▼
