Clues to the aetiology and pathogenesis of herpes gestationis.

In a study of twenty-five patients with herpes gestationis we found that 80% possessed the HLA antigen DR3, which confers increased immune responsiveness and a predisposition to 'auto-immune disease'. In five patients the development of herpes gestationis coincided with a change in sexual partner, suggesting that the development of herpes gestationis may depend on exposure to an antigen derived from the father. This might share determinants with a component of the basement membrane zone of skin. Although anti-basement membrane zone antibodies are present in HG it is not clear whether they play a pathogenic role. The infrequency of neonatal involvement and the lack of correlation between immunofluorescence findings and clinical activity in our patients suggested that the antibodies might be a result of tissue damage rather than its cause. Two patients in our study were exceptional in that episodes of herpes gestationis were followed by normal pregnancies. In these patients the relationship of their DR antigens to those of the fetus may have been important in determining whether or not the pregnancy would be affected by herpes gestationis.