Monophosphoryl lipid A-5

Monophosphoryl lipid A-5 (MPLA-5) is a synthetic or semi-synthetic derivative of lipid A, the biologically active component of lipopolysaccharide (LPS) from Gram-negative bacteria. It acts as an agonist for Toll-like receptor 4 (TLR4), stimulating the innate immune system and serving as a potent immunomodulatory agent. MPLA is produced by hydrolysis of native diphosphoryl lipid A, resulting in removal of all but one phosphate group and various degrees of deacylation, which significantly reduces its toxicity compared to native LPS while retaining immunostimulatory activity[1][4][8]. As a TLR4 agonist, MPLA enhances antigen-presenting cell maturation and promotes Th1-type immune responses. It is primarily used as an adjuvant in vaccines to enhance immunogenicity[1][7][8]. In preclinical models, MPLA has demonstrated protective effects against bacterial infection and radiation injury by augmenting innate immunity without excessive proinflammatory cytokine production[4][6]. The reduced toxicity is attributed to preferential recruitment of TRIF over MyD88 upon TLR4 activation[8].

Other names

3D-monophosphoryl lipid A-5 triethylamine