Protective effect of interferon on target cells exposed to cellular cytotoxicity

In order to explore by immunological methods the interferon-induced cell membrane modulation, the effect of interferon in parental and monkey-mouse hybrid cells was studied in the presence of sensitized lymphocytes from isologous mice. After primary immunization to the hybrids, both parental interferons increased the lymphocyte-induced specific cytotoxicity in the same hybrid cells used as targets. In addition, a significnt increase of spontaneous lysis due to the two interferons was observed. In contrast, after secondary sensitization, in spite of the higher specific cytotoxicity induced by the lymphocytes, the same interferon preparation significantly protected the cells. These results are probably related to a greater number of sensitized effector cells after secondary sensitizationn. It is likely that, although interferon increases the affinity of sensitized T lymphocytes for the target cell membrane, in case of unsuccessful encounters, the target cells become resistant to new hits. Interferon could augment the number of such immune cells.