title: Signal requirement for induction of MHC-unrestricted antitumor cytotoxicity of human T cell CD4+/CD8+ subpopulations.
abstract: The role of cosignalling in the generation of MHC-unrestricted cytotoxicity of T cells was studied with CD4+ and CD8+ sub-populations highly purified (> 98%) by immunomagnetic cell sorting using OKT4 mab, Dynal anti-CD4 mab, OKT8 mab, Dynal anti-CD8 mab, and OKT3 mab. Cytotoxicity was determined in 4 h cytotoxicity assays against K562 tumor cells known to lack expression of MHC class 1 and class 2 antigens, thus avoiding interference with anti-CD4- or anti-CD8-mediated signalling. Signal transfer was induced via CD4, CD8, CD3, IL-2 receptor and RG receptor specifically interacting with a plant rhamnogalacturonan (RG). In CD8+ cells, the first signal delivered by the sorting mab (immobilized OKT8 or Dynal anti-CD8 or OKT3) only induced low MHC-unrestricted cytotoxicity but committed the cells to develop largely enhanced cytolytic potential upon stimulation with a second (IL-2 or RG) or third (OKT3, IL-2, RG) signal. The highest cytolytic potential was achieved by cumulative signalling via CD8, CD3, IL-2 receptor and RG receptor. The generation of MHC-unrestricted cytotoxicity of CD8+ cells correlated with increased effector cell/target cell conjugate formation. In CD4+ cells, OKT4 as sorting mab induced very low cytolytic potential, and a moderate committment to IL-2 signals but a stronger one to RG signals, yielding further cytotoxicity enhancement. The highest cytolytic potential was obtained by cumulative signalling via CD4, IL-2 receptor and RG receptor. Dynal anti-CD4 mab was inefficient and OKT3, as sorting mab of CD4+ cells from CD8-depleted PNAC, appeared to block subsequent OKT4-induced generation of MHC-unrestricted cytotoxicity by delivering a negative signal. Immobilized OKT3 as second signal present in cultures of OKT4-sorted CD4+ cells was inefficient. Surprisingly, soluble OKT3 together with IL-2 delivered a positive signal in cultures of OKT4-sorted CD4+ cells.
authors.affiliation: Friedrich-Miescher-Laboratorium der Max-Planck-Gesellschaft, Tuebingen, Germany.
authors.forename: H G
authors.initials: HG
authors.lastname: Zhu
authors.forename: A
authors.initials: A
authors.lastname: Klein-Franke
authors.forename: F A
authors.initials: FA
authors.lastname: Anderer
mesh_terms: D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007371:Interferon-gamma / Q000502:physiology; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008285:Major Histocompatibility Complex; D016853:Muromonab-CD3 / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D007376:Interleukin-2; D016853:Muromonab-CD3; D007371:Interferon-gamma