title: Comparison of methods for detecting specific IgM antibody in infants with congenital rubella.
abstract: Serum specimens from 14 infants with congenital rubella were examined for specific IgM antibody by six different methods. IgM-containing fractions were separated either by sucrose density-gradient centrifugation or by gel filtration through Sephadex G-200, and were then tested by the indirect immunofluorescence technique and by the haemagglutination-inhibition (HI) test (long-and short-incubation methods). Immunofluorescence staining of density-gradient fractions detected specific IgM in all 14 infants. The HI test (long method), applied to density-gradient fractions, was almost as sensitive, detecting antibody in 13 infants; the short method was less sensitive. The gel-filtration technique proved to be generally less satisfactory than sucrose density-gradient centrifugation. Evidence was obtained for the occurrence of as yet unclassified non-specific inhibitors in the serum of some infants. These inhibitors were deposited with the IgM on sucrose-density gradients and they could have been mistaken for rubella-specific IgM antibody, particularly in the HI test (long method).
mesh_terms: D000914:Antibodies, Viral / Q000032:analysis*; D002499:Centrifugation, Density Gradient; D002675:Child, Preschool; D002850:Chromatography, Gel; D005455:Fluorescent Antibody Technique; D006385:Hemagglutination Inhibition Tests / Q000379:methods; D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis*; D007223:Infant; D012409:Rubella / Q000151:congenital / Q000276:immunology*; D012412:Rubella virus / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M