RELATIONSHIP BETWEEN MATERNAL AND NEONATAL LEVELS OF ANTIBODIES TO 48KDA SSB(LA), 52 KDA SSA(RO), AND 60 KDA SSA(RO) IN PREGNANCIES COMPLICATED BY CONGENITAL HEART-BLOCK

Objective. Since there is suggestive but, to date, indirect evidence t hat maternal anti-SSA(Ro) and SSB(La) antibodies are pathogenic in con genital heart block (CHB), we explored the hypothesis that binding to fetal tissues would result in selective depletion of autoantibodies fr om the neonatal circulation. Methods. Maternal and umbilical cord leve ls of anti-48 kDa SSB(La), anti-52 kDa SSA(Ro) and anti-60 kDa SSA(Ro) antibodies were measured by ELISA and immunoprecipitation at parturit ion in 15 pregnancies complicated by CHB. A control group consisted of 13 pregnancies in which the mother was known to have antibodies to ei ther SSA(Ro) and/or SSB(La) and the children did not have CHB. Results . The ratios of maternal to cord serum levels of anti-48 SSB(La), anti -52 SSA(Ro) and anti-60 kDa SSA(Ro) antibodies ranged from 0.71 to 2.3 8 in both affected and unaffected pregnancies. The mean ratio obtained for each of the 3 autoantibodies was not significantly different betw een the 2 groups. Moreover these ratios did not significantly differ f rom the mean ratios obtained for total IgG levels in either group. Con clusion. These data demonstrate that maternal antibodies to all compon ents of the SSA(Ro) SSB(La) system are efficiently transported across the placenta and are not selectively depleted in the circulation of ne onates with CHB.