Long-term killing of natural killer-resistant target cells by interferon-alpha-, interferon-gamma-, and interleukin-2-activated natural killer cells.
The sensitivity of target cells to natural killer (NK) cell-mediated cytotoxicity was investigated. Five target cell lines were examined for susceptibility to killing by activated NK cells in a 4-hour cytotoxicity assay: one of them (K562) was highly sensitive, while the other four were resistant. However, the four NK-resistant target cell lines were fully susceptible to lysis when the assay was extended to 24 h. The cytotoxic cells that killed the NK-resistant target cells in a 24-hour assay were plastic- and nylon wool-nonadherent human peripheral blood mononuclear cells (PBMC) and their cytotoxicity was increased by interferon-alpha, interferon-gamma, and interleukin-2. Further, the cytotoxic activity of PBMC in the long-term assay was associated with large granular lymphocytes purified on a Percoll gradient, that killed the NK-sensitive cell line K562 in a 4-hour assay. All of the above are general criteria to qualify the cytotoxic cells as NK cells. Thus, the NK-resistant phenotype may not reflect absolute immunity to NK-mediated lysis, but it may reflect the different rates at which various target cell lines can be killed.
Sarzotti
M
M
Department of Microbiology, University of Texas Medical Branch, Galveston.
Klimpel
G R
GR
Baron
S
S
D002460:Cell Line; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic; D007370:Interferon Type I / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism*; D007376:Interleukin-2 / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D011994:Recombinant Proteins; D013997:Time Factors; D014407:Tumor Cells, Cultured
D007370:Interferon Type I; D007376:Interleukin-2; D011994:Recombinant Proteins; D007371:Interferon-gamma