The adjuvanticity of interleukin 1 in vivo.

Interleukin 1 (IL 1) was shown to enhance in vivo secondary antibody responses of mice to a protein antigen. The activity was found to be dose and time dependent. The maximum enhancing effect was obtained with 2000 LAF units of IL 1 given 2 hr after the priming dose of antigen. The observation is consistent with the in vitro immunoenhancing activities of IL 1 and strongly suggests that this protein may be an important mediator of host defense responses, as well as of the stimulatory effects of some adjuvants.