Monophosphoryl Lipid A

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A modified form of lipid A, the biologically active part of Gram-negative bacterial lipopolysaccharide (LPS) endotoxin, and a Toll-like receptor 4 (TLR4) agonist, with potential immunostimulatory activity. As a vaccine adjuvant, monophosphoryl lipid A (MPLA) stimulates both cellular and humoral responses to the vaccine antigen. Compared to LPS, MPLA exerts a similar immunostimulatory activity but with reduced toxicity.

**Synonyms:** - 3-Deacylated Monophosphoryl Lipid A - 3-O-Desacyl-4'-Monophosphoryl Lipid A - MONOPHOSPHORYL LIPID A - MPL - MPLA