Neonatal lupus erythematosus: maternal IgG antibodies bind to a recombinant NH2-terminal fusion protein encoded by human alpha-fodrin cDNA.

IgG antibodies to a cleavage product of alpha-fodrin (120 kDa alpha-fodrin) have recently been identified as organ-specific autoantibodies in primary Sjögren's syndrome. In this study, we examined seroreactivity of mothers and infants with neonatal lupus erythematosus (NLE) to a recombinant NH2-terminal protein (120 kDa alpha-fodrin) of human alpha-fodrin. Serum samples were collected during the perinatal period in seven pregnancies of five mothers delivering offspring with NLE. Anti-120 kDa alpha-fodrin antibodies were identified by immunoblotting in six of seven perinatal maternal sera of offspring with NLE: one of two congenital heart block offspring and all five offspring with cutaneous NLE. These antibodies were placentally transmitted to infants. One of the five mothers had primary Sjögren's syndrome, and four were asymptomatic. One asymptomatic mother did not demonstrate anti-120 kDa alpha-fodrin activity at the time of the first delivery of a congenital heart block infant, but was found to be positive at the time of subsequent delivery of a second child with cutaneous NLE. We propose that maternal antibodies to 120 kDa alpha-fodrin may be an additional serologic marker for the risk of NLE in anti-Ro/SS-A positive women.