EFFECTS OF CONCANAVALIN A ON THE ANTIVIRAL AND CELL GROWTH INHIBITORY ACTION OF HUMAN INTERFERONS

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Abstract
Sensitivities of human transformed cell line RSa and its variant cell line IFr to the cytotoxicity of Con A were compared. IFr cells were more resistant than RSa to Con A. Con A-resistant cell lines, Con Ar-1 and Con Ar-3, were isolated from RSa, and they were slightly more sensitive than RSa cells to the cell growth-inhibitory actions of interferons. Agglutinability of RSa, IFr, and Con Ar cells by Con A was compared and found to be almost equal. The combined effects of Con A and interferon upon growth and viability of these cell lines were tested. When RSa and IFr cells were treated simultaneously with Con A and Le-IF, growth of the cells was suppressed more markedly than when treatment was with Con A or Le-IF alone. To clarify the mechanism of this phenomenon, binding of 125I-labeled Con A was examined. Though ther wee some differences, both leukocyte and fibroblast interferon enhanced the binding of Con A to RSa cells and also in Con Ar cells but, in interferon-resistant IFr and HEC cells, enhancement of Con A binding was low or not observed. Therefore, the combined effect of Con A and interferon on the inhibition of cell growth is not considered to be merely due to the enhanced binding of Con A by interferon action. Successive treatment of RSa or Con Ar cells with Con A and interferon did not enhance the antiviral action of interferon at all. On the contrary, simultaneous treatment with Con A and interferon suppressed the antiviral action of interferon, depending on the concentration of Con A used. Thus, the effect of Con A on the antiviral and cell growth-inhibitory actin of interferon seems rather different.