Rapid activation of ornithine decarboxylase by mitogenic (but not by nonmitogenic) ligands in human T lymphocytes.

The T cell mitogens, concanavalin A and the monoclonal antibody OKT3, cause a rapid activation of ornithine decarboxylase (ODC) activity in human T lymphocytes, maximal within 10 min of mitogen addition. Nonmitogenic ligands to T cell surface structures do not induce ODC. The enzyme induction is dependent upon an intact mobility of ligand-receptor complex, requires a functioning energy metabolism, but is independent of de novo protein synthesis. The early induction of pre-existing ODC molecules appears to be specifically linked to the initiation of T lymphocyte proliferation.