Polysaccharides or Phospholipid Adjuvants

Polysaccharides belong to a class of natural polymers consisting of glycosidically linked carbohydrate monomers. They are capable of activating various immune cells such as macrophages, T lymphocytes, B lymphocytes, and NK cells, leading to the secretion of immune-related molecules. Monophosphoryl lipid A (MPLA), a polysaccharide derivative, has been shown to be an immunologically active adjuvant by binding to TLR4.

Phospholipids play a crucial role in modulating both innate and adaptive immune responses through various mechanisms, serving as precursors for secondary mediators. These lipids are essential for the process of phagocytosis, a key aspect of innate immunity. Additionally, some lipids affect the curvature of the membrane, influencing the formation of phagosomes. They also recruit signaling proteins through interaction with specific lipid-binding domains and provide an electrostatic potential at the membrane surface to attract oppositely charged key signaling and effector proteins.