INFECTION OF K562 CELLS WITH INFLUENZA-A VIRUS INCREASES THEIR SUSCEPTIBILITY TO NATURAL-KILLER LYSIS

Natural killer (NK) cells play a role in the natural immunity against tumor cells. In the present study, we demonstrate that infection of th e NK-sensitive tumor cell line K562 with influenza A virus caused a su bstantial increase in lysis of up to sevenfold when compared to noninf ected cells. Similar to NK cells, IL-2-activated killer cells exhibite d higher lytic activity against virus-infected K562 cells. This effect of the virus correlated with the increase in the expression of intrac ellular adhesion molecule-1 (ICAM-1) on K562 cells. Changes in the sus ceptibility to NK lysis were accompanied by alterations, within minute s, in the cytoskeleton as detected by intracellular fluorescein fluore scence polarization measured on the Cellscan, a static cytometer. The possible role of ICAM-1 and the cytoskeleton in the cytotoxic response of NK cells is discussed.