The effect of Biostim (RU-41740) on the expression of cytokine mRNAs in murine peritoneal macrophages in vitro.

The immunomodulatory agent Biostim (RU-41740) was investigated for its ability to induce the expression of cytokine mRNAs in murine peritoneal macrophages in vitro. Northern blot analysis showed that in quiescent macrophage populations, both IL-1 alpha and IL-1 beta mRNA levels were dramatically increased in response to 1 microgram/ml Biostim. Dot-blot analysis showed that in quiescent macrophage populations the expression of mRNAs for IL-1 alpha, IL-1 beta, IL-6 and TNF-alpha could be elevated by concentrations of Biostim as low as 1-10 pg/ml, detectable after 3 h exposure. In parallel experiments LPS was effective only at the higher concentration of 10 ng/ml. Time-course analysis showed that the expression of these cytokine mRNAs was transient, peaking after 1-3 h; only transcripts of IL-1 beta were detectable after 23 h exposure. No effects were seen on the expression of actin, a high-turnover housekeeping gene. We propose that this type of analysis represents a sensitive, specific and reproducible method for assessing the ability of drugs and chemicals to modulate the expression of cytokines that play a pivotal role in the induction of the immune response.