The utility of IgA antibody to human immunodeficiency virus type 1 in early diagnosis of vertically transmitted infection. National Institute of Allergy and Infectious Diseases and National Institute of Child Health and Human Development Women and Infants Transmission Study Group
K. McIntosh, A. M. Comeau, D. Wara, C. Diaz, S. Landesman, J. Pitt, K. Rich, J. Lew, J. Moye and L. A. Kalish
Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, Mass, USA.
OBJECTIVE: To determine the sensitivity and specificity of anti-human
immunodeficiency virus (HIV) IgA in identifying infected infants at or
before 6 months of age among the offspring of HIV-infected mothers. DESIGN:
Prospective comparison of anti-HIV IgA measurement performed in 2 different
laboratories by 2 different methods with the criterion standard of blood
culture. SETTING: Five centers in the United States and Puerto Rico.
PATIENTS: Population-based sample of 156 infants of HIV-infected mothers in
the Women and Infants Transmission Study. MAIN OUTCOME MEASURES: Results of
anti-HIV IgA test in relation to the infection status of the infants as
measured by blood culture. RESULTS: Six-month plasma or serum samples were
first tested in the 2 laboratories. The sensitivity and specificity of
anti-HIV IgA in detecting infected infants at this age by laboratories 1
and 2 were 69% and 63% and 100% and 99%, respectively. A look-back study of
samples obtained at birth, 1, 2, and 4 months was then performed on all
infected children and a matched set of uninfected children. The performance
of the test at birth was unsatisfactory in both laboratories (sensitivity
44% and 33%, specificity 43% and 60%), whether peripheral or cord blood was
examined. At 1, 2, and 4 months, the sensitivity of the test was lower than
at 6 months, but specificity was high. A modest correlation of absent
anti-HIV IgA antibody and low percentage of CD4 cells in peripheral blood
was seen at 6 months of age. CONCLUSIONS: The anti-HIV IgA test has
moderate sensitivity and high specificity for the diagnosis of HIV
infection at 6 months of age in the offspring of infected mothers.
