Problem: The possible link between p53-reactive antibodies in multiparous women and exposure to a unique p53 protein during pregnancy was examined.
Method of study: p53-reactive antibodies were evaluated in sera from nulligravid and multiparous women and patients with ovarian cancer by Western immunoblot. Furthermore, the presence of p53 protein was assayed in cord blood by enzyme-linked immunosorbent assay. Cord blood-derived p53 was compared structurally by protein fingerprinting and functionally by gel mobility shift assay to other isolates of p53.
Results: Antibodies reactive with wild-type p53 were observed in 92% of multiparous women and 42% were reactive with one tumor-derived p53 protein. p53 protein was detected in 27 of 154 samples of cord blood. Structural analysis indicated that the fetal p53 resembled the UL-1 p53. Functionally, the fetal and UL-1 protein failed to bind DNA.
Conclusions: Fetal p53 protein seems to be distinct from wild-type p53, characterized by enhanced stability, structural differences and inability to bind DNA, analogous to alternatively spliced variants. Exposure to fetal p53 protein may form the basis for immunologic protection against cancer induced by multiparity.