P220 A previous miscarriage and a previous successful pregnancy have a different impact on HLA antibody formation during a subsequent successful pregnancy

Aim Inherited paternal HLA antigens from the semi-allogeneic fetus may trigger maternal immune responses during pregnancy, leading to the production of child-specific HLA antibodies. The prevalence of these HLA antibodies increases with the number of successful pregnancies. In the present study we investigated the effect of a single prior miscarriage on HLA antibody formation during a subsequent successful pregnancy. Methods Women with a successful pregnancy with one or more prior miscarriages ( n  = 58) and women with a successful pregnancy without a prior miscarriage ( n  = 229) and their children were HLA typed. HLA-antibody analyses were performed in these women to identify whether HLA antibodies were formed against mismatched HLA class-I antigens of the last child. Results The percentage of immunogenic antigens was significantly lower after a single successful pregnancy that was preceded by a single miscarriage ( n  = 18 women) compared to a successful pregnancy that was preceded by a first successful pregnancy ( n  = 62 women). Conclusions Our data suggest that a previous miscarriage has a different impact on child-specific HLA antibody formation during a subsequent successful pregnancy than a previous successful pregnancy. The lower immunogenicity in these women cannot be explained by reduced numbers of immunogenic B-cell and T-cell epitopes. Our observations indicate that increasing gravidity is not related to an increased prevalence of HLA antibodies in a single successful pregnancy that was preceded by a single prior miscarriage.