Maternal autoimmune response to recombinant Ro/SSA and La/SSB proteins in Japanese neonatal lupus erythematosus

Background: Neonatal lupus erythematosus (NLE) is a syndrome characterized by dermatitis and congenital heart block (CHB). The disease is mostly associated with transplacental passage of maternal anti-Ro/SSA and/or La/SSB antibodies. Objective: To examine maternal autoimmune response to recombinant Ro/SSA and La/SSB proteins in NLE with a single ethnic background. Methods: This study examined 12 NLE infants and their mothers. Serum samples were tested by enzyme-linked immunosorbent assay for reactivity with full-length recombinant human 60-kd Ro/SSA, 52-kd Ro/SSA, and 48-kd La/SSB proteins. Results: All 10 infants with skin lesions and/or CHB had maternal antibodies reactive to both the 60-and 52-kd Ro/SSA polypeptide components of the Ro/SSA particle. Anti-60-kd Ro/SSA without anti-52-kd Ro/SSA, or vice versa, was found in mothers of infants who had only hepatic manifestation of NLE. Nine of 12 NLE infants had anti-48-kd La/SSB. Conclusion: In the majority of Japanese infants with NLE, maternal anti-Ro/SSA autoimmune response was directed against both of 60-kd and 52-kd recombinant Ro/SSA proteins. There was no profile of anti-Ro/SSA and La/SSB response unique to mothers of children with CHB or cutaneous manifestations of NLE.