Longitudinal study of sera from lupus mothers of groups I and II with Ro antigens. The sera from lupus mothers of (a) group I and (b)–(d) group II were tested by ELISA before (b), during (g, for gestation) and after (p, for post) pregnancy. The number of weeks is indicated. Mother D had two consecutive pregnancies (D1 and D2). The rectangles represent the period known to be at risk (approximately weeks 16–26 of gestation), knowing that autoimmune-associated congenital heart block most often occurs between 18 and 24 weeks of gestation. Sera were tested at a 1:1,000 dilution. Only the IgG response was evaluated. All samples were systematically tested in at least two independent tests – the results shown in the figure correspond to one complete representative experiment. The sera were considered positive when the optical density (OD) values were ≥0.3 (horizontal lane). All sera were tested with the 48 antigens. Only the Ro antigens showing the highest reactivity are depicted in the figures; ◆, recombinant Ro52; ■, Ro52 peptide 1–13; •, Ro52 peptide 107–122; ◊, Ro52 peptide 277–292; ○, Ro52 peptide 365–382; ▴, La.