Screening of aqueous plant extracts for immunomodulatory effects on immune cells and cytokine production: In vitro and in vivo analyses

This study investigates the immunomodulatory effects of various aqueous plant extracts on immune cells and cytokine production. <i>In vitro</i>, several extracts, including holy basil (<i>Ocimum sanctum</i>), patawali (<i>Tinospora crispa</i>), and Indian borage (<i>Plectranthus amboinicus</i> L.), significantly increased CD3⁺ T-cell populations, while soap pod (<i>Acacia concinna</i>), garlic (<i>Allium sativum</i> L.), and neem (<i>Azadirachta indica</i>) also boosted CD45RA⁺ B-cells. <i>In vivo</i>, the extracts had subtle effects on spleen morphology and Peyer's Patches, with milk bush (<i>Euphorbia tirucalli</i> L.) and Indian borage enhancing T-cell responses, while soap pod stimulated B-cells. Additionally, we observed that Neem and milk bush significantly suppressed B-cell populations. Furthermore, cytokine analysis showed that garlic and patawali reduced IL-2, while soap pod, holy basil, and patawali increased TNF-alpha levels. Soap pod also elevated IL-10 and IL-17A, indicating both anti-inflammatory and pro-inflammatory signaling, while patawali induced an increase in IL-4. In conclusion, Thai medicinal plants show strong potential as both immunostimulants and immunosuppressants. They can enhance lymphocyte proliferation, particularly in T-cells, and modulate B-cell populations. Their aqueous extracts play a key role in regulating Th1, Th2, and Th17 cytokine production. Thus, these plants could serve as natural agents and alternative medicines for boosting or modulating immune function.