Interferon-γ is a strong modulator of NK susceptibility and expression of β2-microglobulin but not of transferrin receptors of K562 cells

Abstract

The human cell line K562 was treated with human natural leukocyte interferon (IFN-α) and recombinant immune interferon (IFN-γ). Cell cultures exposed to both types of IFNs displayed a reduced susceptibility to the cytotoxic activity of human PBL (NK activity). While this effect occurred preferentially at high doses of IFN-α, as little as 10 U/ml of IFN-γ caused a marked decrease in susceptibility to NK-cell-mediated lysis. Using a monoclonal antibody against human β2-microglobulin (β2M) a low level of specific binding to K562 cells was detected. The binding increased after treatment with IFN-α (1.4-fold) and IFN-γ (1.7-fold). The expression of transferrin receptors (TR) was not changed significantly. A hybrid cell line between K.562 and a Burkitt's lymphoma-derived cell line displayed a similar pattern of response to IFN-α and IFN-γ as did K562, when effects on NK susceptibility, β2M expression, and TR expression were studied. The Burkitt's lymphoma line PUT showed no consistent changes in expression of β2M and TR. These results demonstrate that IFN-γ is highly efficient in modulating the NK susceptibility, and the expression of β2M on K562. The presented data do not support a role for expression of TR as the only property that determines the degree of NK susceptibility, since there was no correlation between NK susceptibility and TR expression among the cell lines tested or when IFN-treated and untreated cells were compared.