Enzyme-linked immunosorbent assay for quantification of anti-lipid A antibody. Enhancement of sensitivity by antigen immobilization at low pH.
An enzyme-linked immunosorbent assay (ELISA) to quantitate anti-lipid A antibodies in sera has been developed. The sensitivity of the ELISA was improved when the antigen (lipid A) was immobilized at pH 2.0, presumably by enhanced solid-phase adsorption of lipid A which is presumed to be aggregated at low pH. This was also verified by solid-phase immunoradiometry in which a four-fold improvement in the signal-to-noise ratio was observed when antigen coating was performed at pH 2.0 as compared to coating at pH 9.6. The enhanced sensitivity permitted the use of low concentrations of lipid A (10 micrograms/ml) for antigen coating of microtiter plates. The assay was able to clearly detect differences in IgG anti-lipid A levels between patients with chronic liver disease and normal controls.
David
S A
SA
Wellcome Trust Research Laboratory, Christian Medical College Hospital, Tamil Nadu, India.
Mathan
V I
VI
D000818:Animals; D001323:Autoantibodies / Q000032:analysis*; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007074:Immunoglobulin G / Q000032:analysis*; D015592:Immunoradiometric Assay; D008050:Lipid A / Q000276:immunology*; D008107:Liver Diseases / Q000276:immunology; D011817:Rabbits; D012680:Sensitivity and Specificity
D001323:Autoantibodies; D007074:Immunoglobulin G; D008050:Lipid A