Human immunodeficiency virus-specific IgA in infants born to human immunodeficiency virus-seropositive women
R. A. Livingston, N. Hutton, N. A. Halsey, R. L. Kline, M. Joyner and T. C. Quinn
Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Md, USA.
OBJECTIVE: To determine the sensitivity and specificity of human
immunodeficiency virus (HIV)-specific IgA for vertically transmitted HIV
infection, particularly during the first month of life.
DESIGN/SETTING/PATIENTS: Prospective cohort study of 140 infants born to
HIV-seropositive women in a large urban teaching hospital and of 248 older
infants and children referred for diagnosis and treatment of HIV infection.
MAIN OUTCOME MEASURES: The HIV-specific IgA immunoblot results were
compared with the infection status of patients as determined by Centers for
Disease Control and Prevention (Atlanta, Ga) criteria or by sequential
early diagnostic assays for HIV. Sensitivity, specificity, and predictive
values were calculated for each age range. RESULTS: Among infants studied
from birth, the rate of vertical transmission of HIV was 21.6% (25/116).
The sensitivity of HIV-specific IgA for the first month of life was 8.0%
(2/25), and the specificity was 90.1% (82/91). Sensitivity increased
progressively during the first year of life, and the negative predictive
value was 94.6% by 6 to 8 months of age. The positive predictive value of
this assay was 18.2% for neonates but was 96% to 100% after the first month
of life. CONCLUSIONS: False-positive test results for HIV-specific IgA
occurred with diminishing frequency during the first 4 weeks of life, and
the frequency of detectable HIV-specific IgA was similar among the
HIV-infected and uninfected groups at this age. Beyond 1 month of age,
detection of HIV-specific IgA is highly specific and is a useful
serum-based assay for early diagnosis of HIV infection. These results
suggest that maternal-fetal transfusion is common and support the
hypothesis that the majority of maternal-fetal transmission of HIV occurs
around the time of parturition.
