Enhanced diagnostic specificity in human filariasis by IgG4 antibody assessment.
Phosphocholine (PC), an immunodominant molecule present on a wide range of organisms, including filariae, evokes antibody responses that lead to false-positive reactions in routine serological assays. Humans essentially do not respond to PC in the IgG4 subclass; therefore, by configuring an enzyme immunoassay to assess antibodies of the IgG4 subclass only, we were able to eliminate serological false-positive results in 32 of 34 cross-reactive sera from patients with non-filarial parasitic infections. Specificity was thus greatly enhanced with minimal loss of sensitivity. Because preadsorption of these cross-reactive sera to remove antibodies to PC eliminated only approximately 50% of the original cross-reactivity, other shared epitopes (perhaps similar to PC) are also likely to be restricted by IgG subclass.
Lal
R B
RB
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
Ottesen
E A
EA
D000818:Animals; D000909:Antibodies, Helminth / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D000947:Antigens, Helminth / Q000276:immunology; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D005189:False Positive Reactions; D005368:Filariasis / Q000175:diagnosis*; D005370:Filarioidea / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis* / Q000096:biosynthesis / Q000276:immunology; D010767:Phosphorylcholine / Q000276:immunology; D011237:Predictive Value of Tests
D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D000939:Epitopes; D007074:Immunoglobulin G; D010767:Phosphorylcholine