The use of cord serum and indirect viral immunofluorescence as a method of evaluating the immunological specificity of a fluorescein-labelled anti-human IgA conjugate

Maternal and cord sera, obtained simultaneously, were compared by indirect immunofluorescence for the presence of IgG and IgA antibody specific for poliovirus, measles virus and herpes simplex virus. In paired maternal and cord sera virus-specific IgG is present in equal amounts; virus-specific staining by an anti-IgA conjugate was produced by maternal sera and not by cord sera. We believe that a comparison of virus-specific staining by a maternal serum with that produced by the corresponding cord serum using fluorescein-labelled anti-human IgG and IgA conjugates provides an excellent method of excluding cross-reactivity between an anti-human IgA conjugate and IgG.