CD2 and TLR4 agonist
As adaptive cellular immune response, saponins interact directly with the CD2 surface receptor of T cells directly promoting their activation. QS-21 is identified as a potential TLR4 agonist.
Innate and adaptive response
Saponin adjuvants generate a biological effect, in both innate cellular and adaptive immune responses. Saponins are an immunostimulatory adjuvant. Saponins induce infiltration of pro-inflammatory cells, release of DAMPs at the site of inoculation and activation of migratory and resident lymph node antigen presenting cells.
Humoral and Cellular response
Saponins are capable of inducing antigen cross-presentation by professional antigen presenting cells, i.e. promoting presentation to CD8+ T cells via MHC-I which favors the cytotoxic response.
