Lymphocyte binding to K562 cells: effect of target cell irradiation andcorrelation with ICAM-1 and LFA-3 expression
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Abstract
Tumor irradiation induces modifications in the interaction of surviving target
cells with immune cells. This interaction is mediated by adhesion molecules,
whose expression can be strongly altered by radiation treatment. Here the
probably of K562 tumor cells for lymphocyte binding was studied after exposure of
target cells to different doses of gamma-radiation. Results were correlated to
the expression of ICAM-1 and LFA-3 adhesion molecules on target cells. Radiation
treatment enhanced the expression of both ICAM-1 and LFA-3 on the surface of
target cells in a dose and time of culture-dependent fashion, reaching a maximum
24 hrs postirradiation, when also lymphocyte binding was increased. 10-30 Gy
irradiation of K562 cells in vitro induces after 24 hrs, an up-regulation of
ICAM-1 and LFA-3 expression that, in turn, increase lymphocyte binding, making
tumor cells more exposed to cytotoxic attack. The progressive morphological
damage induced by radiation, documented by the scattering singlas in flow
cytometry and by electron microscopy analysis of irradiated K562 cells, induced,
particularly at delayed times of culture in high doses irradiated cells,
alterations of the target cell surface that might prevent the correct interaction
with immune cells