Differential role of Zn2+ in antigen- and mitogen-induced lymphokine production

The effect on human lymphokine production in viro of phenanthroline, a Zn2+-chelating agent and an inhibitor of carboxypeptidases A and B, was tested. The elaboration of leucocyte migration inhibitory factor (LIF) by tuberculin-sensitized mononuclear cells stimulated with the specific antigen was reduced in a dose-dependent manner, an effect completely restored by addition of excess Zn2+. In contrast, phenanthroline did not affect LIF production by mononuclear cells activated nonspecifically by phytohaemagglutinin. It is hypothesized that the presence of a Zn2+-dependent molecule, possibly a carboxypeptidase, may be necessary for antigen- but not for mitogen-induced lymphokine production.