Anti‐HL‐A Foeto‐Maternal Immunization. Persistence of Antibodies

This study concerns the persistence of antibodies in 42 sera. Twenty‐seven of these, sampled from 12 to 175 weeks after the first sample, remained positive. In general, the titre of the antibodies had decreased. The antibody's specificity either remained the same or, most often, narrowed, due either to the loss of a specificity in multi‐specific sera or to the narrowing of a basic specificity. Some sera that were very broad at childbirth, after a lapse of time acquired a specificity that made it possible to identify the immunizing antigens.