"Immunoregulatory effects of extracts from the stem bark of Albizzia julibrissin Durazz

Abstract

Although there are many disease modifying antirheumatic drugs (DMARDs) available, more safe and effective reagents have yet to be developed. Activated T cells make good targets for DMARD therapy. Therefore, we screened over fifty herbal extracts, and identified that water extract from the stem bark of Albizzia julibrissin selectively killed activated T cells but not naive splenocytes, in vitro. Wb3-3, obtained by further extraction and column chromatography to maximize selective activity, was used for further investigation. Annexin-V and caspase activity assay revealed that WB3-3 killed activated T cells by inducing apoptosis, which was mediated through mainly caspase-8 rather than caspase-9. The effect of WB3-3 in vivo was conlirmed by the elimination of V8- but no V6-T cells following activation with Streptococcal Enterotoxin B (SEB). Furthermore, WB3-3 inhibited neither CD25 upregulationnor proliferative response, and rather increased IL-2 secretion during Con A activation of naive T cells.Our results imply the potential of WB3-3 to include a lead compound for a new immunoregulatory drug.