SIMILARITIES AMONG FACTORS THAT RENDER MACROPHAGES TUMORICIDAL IN LYMPHOKINE AND INTERFERON PREPARATIONS

  • 1 January 1978
    • journal article
    • research article
    • Vol. 38  (4) , 1003-1007
Abstract
Lymphokine preparations, including supernatants derived from antigen-stimulated BCG-immune spleen cell cultures and normal spleen cells incubated with insoluble concanavalin A [con A], were compared with partially purified [mouse fibroblast] L-cell interferon for the ability to render resting macrophages nonspecifically tumoricidal in vitro. Significant activation of macrophages by lymphokine preparations occurred at concentrations as low as 0.5 and 0.25% of the assay mixture for antigen-stimulated and con A-induced lymphokine, respectively. These end point concentrations were each determined to contain 0.3 unit of interferon/ml. Supernatants obtained from unstimulated normal spleen cells, con A-treated nu/nu spleen cells, or BCG-immune spleen cells in the absence of sensitizing antigen did not enhance macrophage tumoricidal function and lacked interferon. Activation by L-cell interferon required at least 1 unit/ml. The macrophage-activating factors contained in lymphokine and interferon preparations were stable at pH 2 and at 56.degree., destroyed when heated at 80.degree. for 30 min and inactivated by trypsin. The data demonstrate common properties for the induction of tumoricidal macrophages by these diverse preparations.