Neonatal Guillain-Barre syndrome - Blocking antibodies transmitted from mother to child

Objective: To investigate the role of blocking antibodies in neonatal Guill ain-Barre syndrome (GBS) occurring 12 days postpartum in a child born to a mother with ongoing GBS. Methods: We studied plasma filtrate, purified IgG, and monovalent Fab fragments from the affected mother and serum from the n eonate as well as serum samples after recovery from disease 3 months later. Experiments were performed on the hemidiaphragms of adult mice and neonata l and juvenile rats. Quantal endplate currents were recorded with the perfu sed macro-patch clamp electrode. Results: A dual effect was seen. Serum fro m mother and infant depressed quantal content by approximately 90% and redu ced the amplitude of postsynaptic currents by 30 to 40%. The antibody natur e of the blockade could be confirmed by showing that monovalent Fab fragmen ts were similarly effective as purified immunoglobulin (Ig) G, No IgG antib odies to gangliosides, fetal or adult nicotinic acetylcholine receptor, or voltage-gated calcium channels could be detected, but IgM antibodies to the ganglioside GM1 were present. After recovery from GBS no blocking activity was seen in the sera of mother and infant. To elucidate why neonatal disea se onset was delayed we examined the possible influence of early developmen tal changes in functional properties of the neuromuscular junction and appl ied the mother's active serum to postnatal rats. Although blockade was pres ent in 23-day-old rats, it was absent, in Ei-day-old rats. Conclusion: Tran splacentally transferred blocking antibodies may be specifically directed a t epitopes of the mature but not the fetal neuromuscular junction.