## 2 Effects of Plant Extracts on In Vitro Dendritic Cell Biology and Its Effects in Cancer Cells  
### Dendritic Cells Differentiation and Maturation  
Although the immature DCs have high endocytic activity to capture antigens and the ability to initiate T-cell stimulation [30]. The maturation of DCs is necessary for antigen-specific T-cell immunity [31]. Different types of proinflammatory cytokines (IL-1, TNF-\(\alpha\), PGE2, etc.), lipopolysaccharidesaccharide (LPS) from bacteria and natural products induce DC maturation. Mature DCs show surface expression of costimulatory molecules such as CD40, CD80, CD86, and MHC II, which are essential to produce an antigen-specific T cell immune response [4,29]. It has been reported that different types of plant extracts and their active components have been shown to enhance DC differentiation (Table 1). Pine cone extract, the traditional Japanese herbal plant kampo, and water-soluble extract of the fern _Polyodium leucotomos_ induce DC differentiation both in vitro and in vivo [29].  
Plant-derived polysaccharide (PDP) extracts induce DC maturation and provide antitumor immunity [21]. Plant polysaccharides obtained from the medicinal herb _Polyporous umbellatus_ induce activation and maturation of murine BMDC through TLR [32]. Another study also showed that plant polysaccharide (PLP) from _Pueraria lobata_ induces surface phenotype expression of CD40, CD86, and major histocompatibility complex I/II [27]. The _Dioscorea_ plant extract (DsII polysaccharides) increased the maturation of DCs and also enhanced the TCL-loaded DC-mediated T-cell activation and proliferation, which induces strong immunity against melanoma in animals [26]. It has been found that a plant of _Nicotiana benthamiana_ does not affect dendritic cell differentiation but induces maturation. The plant does not have any effect on antigen uptake capacity [23]. Neem leaf glycoprotein (NLGP) induces the maturation of DCs and also increases the expression of MHCs and co-stimulatory molecules CD83, CD80, CD86, and CD40 [33]. Dendritic cells pulsed with Astragalus polysaccharide showed increased DC maturation and induced allogeneic lymphocyte proliferation. It also increased the expression of CD11c and MHC class II molecules on DCs [34,35]. The immunomodulatory effect of aged garlic extract 14 kDa protein showed increased expression of CD40 surface phenotypes of DCs, but it had no effect on CD86 and MHC II expressions [36]. The seed extract of _Plantago asiatica_ induces the maturation of DCs and also increases the expression of MHC II, CD80, and CD86 surface phenotypes on DCs [37]. Medicinal herbs, including _Thymus daenensis, Thymus vulgaris_, and _Zataria multifora_, combinedly induce DC-mediated T-cell activation. The herbs also showedincreased CD40 surface phenotype expression on DCs [38]. [PERSON] et al. showed that licorice roots containing 18-\(\alpha\) and 18-\(\beta\)-glycyrrhetinic acid stimulate DCs that enhance T-cell immunity against specific antigens [39]. Some plant components were found to initiate DC differentiation and maturation in vitro, such as lupine acetate of cortex periplocae, the aqueous and organic fractions from _Petiveria alliacea_, an acidic polysaccharide from ginseng (_Panax ginseng_), and _Lycium bararum_ polysaccharide (LBP) [29]. In the same way, another traditional Chinese herb, _Achyranthes bidentata_, induces surface phenotypes and maturation of DCs and also boosts immune responses in mice [40]. The fermented mistletoe extract component matures DC\({}_{\text{S}}\) and is used as an adjuvant for the treatment of cancer patients [41].