Abstract 143 Poster Session II, Sunday, 5/2 (poster 246)

Maternal lupus erythmatosus is manifest by fetal wastage and congenital heart block, thought to be due to trans-placentally passed maternal auto-antibodies (Ab). We investigated an autoimmunized murine model for antibody responses, fetal wastage, fetal heart rate & rhythm and neonatal rhythm.

METHODS: Eight wk. old female C3H/HeJ mice were immunized and boosted with bovine Ro60 (n=9) or La48 (n=9) antigen (Ag) in Freund's adjuvant or adjuvant alone (n=8). Ro or La antibody optical densities (OD) were measured sequentially. Following mating, individual fetuses were assessed by embryonic Doppler ultrasound (ATL, 10MHz probe) from 14 to 21 days gestation to determine heart rate and rhythm. Offspring were counted and underwent ECGs, then sacrificed for cardiac pathology. Ab level was compared by t-test, as were fetal and neonatal heart rates and neonatal PR intervals. Proportions of prenatal block or bradycardia were compared by Chi-square test.

RESULTS: (Table)

Table 1 No caption available
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CONCLUSIONS: Immunization with bovine Ag results in a high OD of the corresponding Ab, as well as molecular spreading to other Ab. Fetal echocardiography is able to detect frequent 2°block in utero in Ro-immunized mice, but this conduction abnormality is not found in surviving neonates. There is a tendency toward highest fetal wastage in La-immunized mice. Assessment of murine models of autoimmune conduction system disease is enhanced by fetal ultrasound assessment of rhythm.