Two-Stage Purification of Recombinant Antibodies Using Non-Ionic Detergent Prevents Endotoxin-Induced Macrophage Activation: The Case of Bispecific Mini-Antibody MYSTI-2

Escherichia coli is one of the most common producers of recombinant proteins, including therapeutic antibody fragments. However, the outer membrane of E. coli contains high levels of lipopolysaccharide (LPS, also known as endotoxin), which can activate innate immune receptors, trigger immune responses, and induce systemic inflammation that may progress to septic shock. Ensuring extremely low endotoxin levels in preparations intended for in vivo applications is critically important. In this study, we investigated the endotoxin content in preparations of the bispecific mini-antibody MYSTI-2 produced in two E. coli strains: the Rosetta strain, which synthesizes conventional LPS, and the ClearColi strain, which synthesizes potentially non-toxic form of LPS. Our results demonstrate that near-complete removal of LPS can be achieved only through the use of a non-ionic detergent during purification, regardless of the bacterial strain used for protein production.