Antibodies (IgG and IgM) recognizing a 240 kD antigen of the cat fetal
brain were found in sera of healthy people and in sera (IgG) obtained
at uncomplicated delivery from the umbilical cord of the newborn infa
nt. The method applied was immunoblotting. Using the same method, the
240 kD antigen could not be detected in the adult brain or other fetal
tissues. It seems that the antigen is specific for the fetal brain. T
he role of the antigen and the origin of generation and significance o
f function of the antibodies in the circulation are the objects of our
further studies.