Monophosphoryl lipid A (MPLA) is a natural agonist for the toll-like receptor-4 (TLR4). It is useful as an adjuvant in immunization. MPLA is a safe prophylactic agent and has immunotherapeutic applications. It induces tumor necrosis factor and interleukin (IL)-1β, however not as efficient as lipopolysaccharide (LPS). MPLA improves immune response during bacterial sepsis infection.
