Immune responses to SS-A 52-kDa and 60-kDa proteins and to SS-B 50-kDa protein in mothers of infants with neonatal lupus erythematosus.

Mothers who have anti-SS-A/Ro and anti-SS-B/La antibodies have a greater risk of bearing infants with neonatal lupus erythematosus (NLE). However, most mothers with anti-SS-A/Ro and anti-SS-B/La antibodies give birth to infants with no evidence of NLE. We studied mothers who had the combination of clinical evidence of connective tissue disorder, positive antinuclear antibody and positive anti-SS-A/Ro and/or anti-SS-B/La antibodies. We analysed SS-A/Ro and SS-B/La antibody responses to recombinant 60-, 52- and 50-kDa proteins in eight mothers of NLE infants and 19 mothers whose children did not have NLE. Molecular analysis of the anti-SS-A/Ro and anti-SS-B/La antibodies was carried out by enzyme-linked immunosorbent assay using recombinant 60-, 52- and 50-kDa proteins. The mothers of children with cutaneous NLE were all positive for a high titre of 50-kDa protein. Mothers of children with NLE with complete heart block (CHB) were positive for 52- and 60-kDa proteins. We conjecture that anti-SS-B/La antibody influences the development of cutaneous NLE, and that anti-SS-A/Ro antibody influences the development of NLE with CHB.