Mechanisms in in vivo release of lymphokines. III. Separation of gamma-interferon (IFN gamma) from cytotoxicity in inbred strains of mice.

Abstract

Inbred strains of mice sensitized with BCG and challenged with old tuberculin (OT) vary in their capacity to release IFN gamma and MIF into circulation. Experiments were performed to correlate the presence of IFN gamma with that of the cytotoxic effect in an attempt to learn whether these two activities in the sera may be separated. Sera from eight inbred strains were obtained at times after challenge and assayed for IFN and for cytotoxic activity. A correlation did not exist between the titers of IFN gamma and the levels of cytotoxicity, i.e. sera from RF/J mice without detectable titers of IFN gamma had cytotoxic activity, while sera from C57BL/KsJ mice that had titers of IFN gamma were not cytotoxic. Regulation of IFN gamma titers could be achieved by administration of complete Freund's adjuvant to BCG sensitized mice. However, similar differences were not detected in cytotoxic activity. Therefore, IFN gamma may be released, or the activity of IFN gamma may be expressed in the circulation, in the absence of cytotoxicity.