The effect of drugs used in anticoagulation therapy on T lymphocyte activation in vitro. II. Warfarin inhibits T lymphocyte activation.

The effect of warfarin on T lymphocyte activation in vitro was investigated. Warfarin was found to cause a dose-dependent inhibition of both antigen- and PHA-stimulated proliferation. The drug had to be present during the early steps in T lymphocyte activation to cause inhibition. Warfarin seemed to have no effect on antigen processing or presentation. Warfarin inhibited Interleukin 2 (IL-2) production, but had only minimal effects on expression of IL-2 receptors or IL-2 dependent proliferation. The inhibition in most in vitro models was found only at warfarin concentrations exceeding the therapeutic serum level.