The effect of emetine on the immune response of mice.

Emetine (33 mg/kg body weight) administered intraperitoneally blocked the immune response of mice to 10(9) sheep red blood cells (SRBC). The inhibition was almost complete when the drug was administered simultaneously or 24 hr after immunization, while partial inhibition was caused by treatment at 48 and 72 hr. Incorporation of 14C-leucine and 3H-thymidine by spleen cells isolated 4 hr after emetine injection of the mice was strongly decreased. Incorporation was approaching the control level in cells isolated 72-96 hr after emetine administration. However, the incorporation of labeled precursors was less than after SRBC treatment only, even after 72-96 hr. Emetine apparently blocked the development of immune response at an early stage and, in contrast to macromolecule synthesis, the inhibition of the antibody response was irreversible.