Studies of the specificity and cross-reactions of antibodies to lipid A found in juvenile arthritis.
This work was started to determine whether the immunoglobulin G (IgG) reactions with monophosphoryl lipid A (MPL) found in children with arthritis were due to contaminants, a specific site on lipid A, or polyspecific binding. Different lots of MPL were examined by electrophoresis and immunoblot. Competitive inhibition of enzyme-linked immunosorbent assays (ELISAs) by analogs of MPL and biologic materials of clinical interest was used to determine the specificity of the binding site and potential cross-reactions. IgG in all patient sera tested reacted with a single band just < 6.5 kDa on immunoblots of all lots of MPL tested. The ELISAs were inhibited best by analogs of lipid A with an exposed diglucosamine core and intact polar domains. The anti-MPL was also inhibited by fetal bovine collagen types I and II and in some instances by cardiolipin, but not by keratan sulfate, proteoglycan, or DnaK heat shock protein. Lot variation was a persistent technical problem, but no protein contaminant could be demonstrated in any lot. The ELISA and immunoblot results confirmed each other. Immunoblots detected a single band of MPL reactive with IgG. This antibody remains of interest because of its disease association and correlations and because it cross-reacts with collagen and cardiolipin.
Miller
J J
JJ
Lucile Packard Children's Hospital, Stanford University School of Medicine, California 94305.
Olds
L C
LC
D000328:Adult; D000906:Antibodies / Q000276:immunology*; D000918:Antibody Specificity; D000941:Antigens / Q000276:immunology / Q000494:pharmacology; D001171:Arthritis, Juvenile / Q000276:immunology*; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002648:Child; D003429:Cross Reactions; D004586:Electrophoresis; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008050:Lipid A / Q000031:analogs & derivatives / Q000032:analysis / Q000276:immunology*; D008969:Molecular Sequence Data
D000906:Antibodies; D000941:Antigens; D007074:Immunoglobulin G; D008050:Lipid A; C048436:monophosphoryl lipid A