AUTOANTIBODY RESPONSE TO THE RO LA PARTICLE MAY PREDICT OUTCOME IN NEONATAL LUPUS-ERYTHEMATOSUS/

This study was undertaken to determine the role of antibodies against both recombinant Ro (r-Ro) and La (r-La) proteins and polypeptides der ived from the recombinant La protein in predicting fetal and neonatal outcome in children at risk to develop neonatal lupus erythematosus (N LE). All sera were obtained in the perinatal period and quantitative E LISA assays were used. We collected 41 maternal sera within 2 months o f delivery of a child with NLE (21 with congenital heart disease block (CHB) and 20 with dermatologic NLE) and 19 sera from anti-Re and/or a nti-La antibody-positive mothers with systemic lupus erythematosus (SL E) who delivered a child without NLE. All sera were tested for anti-r- La and anti-r-Ro antibodies by ELISA, and most sera were tested for an tibodies directed against La polypeptides by immunoblot. We found sign ificantly higher anti-r-La La antibody levels in the sera from mothers of children with NLE compared with sera from mothers of unaffected ch ildren (0.67 +/- 0.43 versus 0.14 +/- 0.30; P < 0.0001). There was a s tatistically significant difference in the mean anti-r-La levels betwe en the sera of mothers of children with CHB compared with dermatologic NLE (0.51 +/- 0.45 versus 0.83 +/- 0.37 respectively; P = 0.0091). Wh en we examined antibodies directed against the recombinant 52-kD Ro pr otein, there was a statistically significant elevation of titres in th e sera of mothers of NLE children (0.77 +/- 0.35) compared with non-NL E mothers (0.29 +/- 0.39; P < 0.0001). There was no difference in the r-Ro levels between mothers of children with dermatologic NLE compared with CHB (0.82 +/- 0.37 versus 0.71 +/- 0.74; P = 0.32). When we exam ined polypeptides derived from the recombinant La protein, the mean nu mber of polypeptides recognized by sera from mothers of children with NLE was significantly higher than the mean number of polypeptides reco gnized by sera from mothers of unaffected children (5.1 +/- 0.54 versu s 2.3 +/- 0.54 respectively; P < 0.001). More importantly, when we exa mined the individual polypeptides, we found that only sera from mother s of children with NLE and not from mothers of unaffected children rec ognized a polypeptide designated DD (30% versus 0%, respectively). The se studies indicate that the autoantibody response to the Ro/La partic le can differentiate sera from mothers of children with NLE and sera f rom mothers of unaffected children. Furthermore, there was a differenc e in the anti-La autoantibody response between mothers of children wit h CHB and dermatologic NLE. Antibodies directed against the DD polypep tide derived from the recombinant La protein were seen only in the ser a of mothers of children with NLE.