title: CD8+CD11b+ peripheral blood T lymphocytes contain lymphokine-activated killer cell precursors.
abstract: CD3+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 (rIL2) in vitro they 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 alpha/beta chains, but not the gamma/delta 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 IL2 in vitro and 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 rIL2, 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 rIL2. The observed cloning efficiency of 19 +/- 0.3% indicates that a fraction of the cells only could respond to IL2. 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 circulating T cells.
authors.affiliation: Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy.
authors.forename: U
authors.initials: U
authors.lastname: Dianzani
authors.forename: D
authors.initials: D
authors.lastname: Zarcone
authors.forename: V
authors.initials: V
authors.lastname: Pistoia
authors.forename: C E
authors.initials: CE
authors.lastname: Grossi
authors.forename: A
authors.initials: A
authors.lastname: Pileri
authors.forename: M
authors.initials: M
authors.lastname: Massaia
authors.forename: M
authors.initials: M
authors.lastname: Ferrarini
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D016827:CD8 Antigens; D002454:Cell Differentiation; D002478:Cells, Cultured; D002999:Clone Cells; D003602:Cytotoxicity, Immunologic; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D016177:Macrophage-1 Antigen; D008854:Microscopy, Electron; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000145:classification / Q000166:cytology / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D000945:Antigens, Differentiation, T-Lymphocyte; D016827:CD8 Antigens; D007376:Interleukin-2; D016177:Macrophage-1 Antigen; D010835:Phytohemagglutinins; D000135:Acid Phosphatase