Immunotoxicity due to innate immune activation is one of the potential adverse reactions of nucleic acid drug candidates. There are currently no guidelines and standard test systems for determining the potential toxicity of these compounds. In this study, we investigated the basic test conditions for developing an innate immune activation assay using human peripheral blood mononuclear cells.
We examined the suitability of TLR ligands, analytes, culture time, and donors. ODN 2216 and R 848 ligands responded well and were selected as positive controls for this study. There were no major differences in cytokine responses at 24, 36, and 48 h of exposure; we selected the 24-h time point as it was the shortest and the least influenced by acquired immunity. Donors with high expression levels of several CD markers were found to respond well to TLR ligands. If appropriate donor selection becomes possible, the number of donors required may be reduced.
In this study, we found that data variability and outlier evaluation were problematic; therefore, we also examined the method of data analysis. By taking the geometric mean of donors using the median of the data of one donor as the representative value, it was possible to obtain data with small variations between studies.
Although the conditions investigated in this study were very useful for the construction of the test systems, many issues are yet to be clarified, including the selection of appropriate reference compounds and in vitro-in vivo correlation; therefore, further studies are needed.
