Immunogenicity of hydatidiform mole.

The HLA and ABO systems were studied in patients with complete hydatidiform mole (CHM). The study confirmed that CHM can immunize the patient against paternally derived HLA-ABC antigens. In patients who required subsequent treatment for trophoblastic tumours the frequency of antibody detection was much higher (10/14) at the time of treatment than it had been at the time of evacuation (2/14). The source of immunogen was considered to be the stroma of the placental villi. It was demonstrated that in a series of 82 CHMs none of the 25 patients mated to a husband of the same ABO group as her own required treatment for postmole trophoblastic tumours. Among unlike matings 17 out of 57 of the patients required treatment. Thus it appears that trophoblastic proliferation after evacuation of mole is favoured by an ABO difference between maternal environment and the molar tissue.