[Lipoid A antibody titer in humans]

Lipid A is the toxic component of endotoxin in gram-negative bacteria. Antibodies to lipid A are not usually found in healthy persons (or only at a low titer) without a corresponding history of infection. Even gram-negative septicemia is found to be accompanied by only low titers. A completely different situation is seen in patients with chronic or recurrent infections due to Enterobacteriaceae and other gram-negative bacteria. Here it is notable that the antibody titer varies with the type of disorder (e. g. cystitis and pyelonephritis). A severe would infection, e. g. due to Pseudomonas aeruginosa, also leads to measurable lipid A antibody titers. Varying antibody titers can be observed in cystic fibrosis, Crohn's disease, and severe surgical infections. One can conclude that a significantly elevated antibody titer develops during an extensive tissue involvement of long duration and indeed is caused by tissue inhibition by endotoxin. Based on clinical experience, it can be assumed that lipid A antibodies present in the body have a protective effect in septic shock.