Immune complexes containing H-Y antigen and maternal IgG in cord serum

Increased levels of immune complexes are more frequently detected in the serum of newborn males than they are in the serum of newborn females. In one survey of 545 newborns, 21 of 26 (81%) of the babies with high levels of immune complexes in cord serum were boys. To evaluate the hypothesis that this was due in some cases to the synthesis by the mother of antibodies directed against the 'male-specific' H-Y antigen, we tested for presence of IgG antibodies bound to H-Y antigen in serum samples from 263 newborns including 124 girls and 139 boys. Sera from five of the 10 male newborns with high levels of immune complexes contained IgG bound to H-Y; none of the sera from newborn girls had detectable amounts of those immune complexes; and sera from women who had borne males manifested higher levels of IgG reactive with sources of soluble H-Y than sera from women who had borne females.