NATURAL CYTO-TOXICITY IN HUMANS - SUSCEPTIBILITY OF FRESHLY ISOLATED TUMOR-CELLS TO LYSIS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 65  (2) , 257-263
Abstract
The cytotoxic potential of blood lymphocytes from healthy donors was tested against freshly isolated lung cancer cells and the erythroleukemia K562 cell line in short-term 51Cr release assays conducted at an effector:target ratio of 50:1. Most donors exhibited significant activity against K562 cells. By contrast, fresh tumor cells were refractory, only 6 of 30 showing significant cytotoxicity. The low susceptibility of these tumor cells was confirmed in third-party cold inhibition assays in which they interfered minimally with killing of K562 targets under conditions in which unlabeled K562 cells efficiently blocked cytotoxicity. Cells prepared from normal lung tissue and Raji cells also failed to inhibit killing. Although in comparison to the K562 cell line freshly isolated tumor cells were resistant, their susceptibility may not be so low as to be biologically irrelevant, inasmuch as boosting of natural killing activity by interferon induced levels of cytotoxicity against both types of target cell that were unattainable by unstimulated effectors. Interferon-boosted killers were lytic for normal lung cells and the Raji cell line.

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