Umbilical cord blood levels of maternal antibodies reactive with p200 and full length Ro52 in the assessment of risk for cardiac manifestations of neonatal lupus

Abstract

Objective:

Maternal anti-Ro autoantibodies associate with cardiac manifestations of neonatal lupus (cardiac NL), yet only 2% of women with this reactivity have an affected child. Identification of a more specific marker would channel intense monitoring to fetuses at greater risk. This study aims to determine whether autoantibodies against Ro52 amino acids 200-239 (p200) confer added risk over autoantibodies to full length Ro52, Ro60 or La.

Methods/Results:

Anti-Ro-exposed pregnancies resulting in cardiac NL or no cardiac manifestations were identified from the Research Registry for Neonatal Lupus and PR Interval and Dexamethasone Evaluation. Umbilical cord (n=123) and maternal (n=115) samples were evaluated by ELISA. The frequencies of p200, Ro52, Ro60 and La autoantibodies were not significantly different between affected and unaffected children. However, neonatal anti-Ro52 and Ro60 titers were highest in cardiac NL and their unaffected siblings compared to unaffected neonates without a cardiac NL sibling. Although both maternal anti-Ro52 and p200 autoantibodies were less than 50% specific for cardiac NL, anti-p200 was the least likely of the Ro autoantibodies to be false positive in mothers who have never had an affected child. Titers of anti-Ro52 and p200 did not differ during a cardiac NL or unaffected pregnancy from the same mother.

Conclusion:

Maternal reactivity to p200 does not confer an added risk to fetal conduction defects over full length Ro52 or Ro60 autoantibodies. Mothers who may never be at risk for having an affected child have lower anti-Ro60 titers and may require less stringent echocardiographic monitoring compared to women with high titer autoantibodies. © 2012 by the American College of Rheumatology