Immunochemical and Biological Reactivity of Human Anti‐Lipopolysaccharide IgG Obtained by Screening of Blood Donors

Abstract

An anti-lipopolysaccharide (LPS) preparation for the intravenous treatment of septic endotoxic shock was prepared by purifying immunoglobulin G (IgG) from pooled serum from Danish blood donors. The sera were selected by the use of an enzyme-linked immunosorbent assay (ELISA) to screen blood donors for high concentrations of antibodies to a mixture of LPS from 11 different Gram-negative bacteria. ELISA was also used for indirect quantification of IgG antibodies to lipid A, and to rough LPS from Escherichia coli Ra and Salmonella minnesota R60 (Ra). The concentration of human antibodies to the LPS mixture correlated with the concentration of antibodies to the E. coli and S. minnesota rough LPS and to lipid A. The specificity of sera with high concentrations of anti-LPS IgG was investigated by immunoblotting. Sera from individual donors reacted with LPS from different bacteria and recognized different sites on the LPS molecules. The range of specificities to different LPS was increased by the pooling of selected sera. The IgG fraction from the high titre donor pool neutralized biological activities of LPS such as activation of the Limulus amoebocyte lysate reaction and induction of tumour necrosis factor secretion from human monocytes.

Enhancement of lipopolysaccharide-induced tumor necrosis factor secretion by hyperimmune serum from chronic infected patients

“…This is in agreement with the lower potency ofP. aeruginosa LPS for TNF induction [13], which could be due to the slightly different structure of this LPS molecule compared to the S. abortus equi LPS [24]. P. aeruginosa LPS differs from enterobacterial LPS by having a large number of phosphate residues, by the presence of L-alanine in the core, by the occurrence of unusual sugars and amino compounds in the O chain [32,35], and by having fewer and shorter fatty acid residues in the lipid A part arranged asymetric on the glucosamine backbone [4,10,25].…”

“…The inactivation of small amounts of S. abortus equi LPS (0.01 gg/ml) by serum from healthy controls described in this study supports previous studies, in which the LPS-induced IL-1 or TNF response was inhibited by normal human serum or purified serum proteins as lipoproteins, IgG or alpha globulins [9,13,38]. Interesting!y, NHS seemed to have a slightly neutralizing effect on even high concentrations ofP.…”

“…Inhibition of LPS effects by serum from healthy donors has been demonstrated by several authors [13,27,38,41], using the Limulus amebocyte lysate assay. Under certain conditions interaction of serum with LPS has also been shown to prevent LPS-induced mediator release [5,9,29,42] and this inhibitory effect has been shown to involve the lipoprotein fraction of the serum [9], the alpha globulins [38] and naturally occurring IgG anti-LPS antibodies [13].…”

Emergence of autoantibodies to HMGB1 is associated with survival in patients with septic shock

“…So far, we have been unable to detect IgM in either HSA or HMGB1 in the same samples (data not shown). Autoantibodies against TNF-a, another key modulator in sepsis, have been detected in almost 40% of apparently healthy donors, a prevalence that reaches 66% in patients with gram-negative septicemia [20]. We showed here that anti-HMGB1 and anti-HSA antibodies are produced transiently in most cases during the course of the disease.…”

Prospects for monoclonal antibodies in the diagnosis and treatment of bacterial infections

“…Combinations of monoctonals against core glycotipid, certain frequently occurring O and K antigens, warrant study. Most normal subjects have naturally occurring IgM and IgG antibodies to the core glycolipid and lipid A (9,10). Careful monitoring during infection of the relative distribution of the class and subclass of these antibodies will possibly reveal which class or subclass plays a beneficial role (11), as monoclonal antibodies used therapeutically should be of the effective (sub)class.…”