In vivo IL-1 potentiates both specific and non-specific arms of immune response to infection.

Injection of 10(5) U interleukin-1 (IL-1) 4 hr before intravenous infection with Listeria monocytogenes hastens recovery of mice. This is accompanied not only by early stimulation of colony-forming cells in the spleen to levels higher than those in untreated, infected mice but also by accelerated activation of lymphokine-producing, specific T lymphocytes.