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.

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.