HIV antibodies in babies [letter]

Scientists objected to the conclusion of an earlier article about a sensitive Western blot method for detecting IgA and IgM HIV antibodies in the blood of HIV-infected newborns born to seropositive mothers. The authors of the article concluded that the method would set apart infants who are HIV infected from those who are not. They did not consider that other reasons may explain the presence of IgA and IgM HIV antibodies in the newborns bloodstream. For example blood from 37 HIV-seropositive mothers who were in labor had detectable HIV-specific IgG and IgA. 35 had specific IgM. Newborns of mothers with IgA reactivity =or> 8 and IgM reactivity =or> 7 had detectable IgA and IgM but newborns whose mothers had weaker IgA or IgM reactivity had neither detectable specific IgA nor IgM. Thus maternal IgA and IgM molecules pass through the placenta. Mothers with the highest IgA and IgM HIV antibody levels may have had the most severe viremia. Newborns tend not to have an active antibody response at birth since HIV transmission does not occur until the end of pregnancy or during delivery. Another study showed that IgA and IgM antibodies were common in 3-month old infants who were HIV infected had IgA and IgM antibodies. Thus these reasons would reduce the value of the method as indicators of HIV transmission from mother to infant. Presence of IgA or IgM antibodies in the neonatal period do not necessarily indicate HIV infection.