Blocking effects of maternal serum-IgG and placental eluate-IgG on materno-fetal mixed lymphocyte reaction and their individual specificity.

ABSTRACT

The purpose of this study is to clarify the problem regarding individual specificity of maternal serum immunoglobulin G (IgG) and placental eluate IgG that block the unidirectional mixed lymphocyte reaction (MLR) in which maternal and cord blood lymphocytes (lys) were used as responder and stimulator, respectively. Both maternal serum IgG and placental eluate IgG were found to include blocking antibodies (BA) which showed similar blocking effect on MLR. But, in the case of serum IgG, individual specificity of BA on MLR was observed to be less great in MLR done using whole lys or T-enriched lys of the cord blood as stimulator, whereas it became greatly significant when MLR was done using B-enriched lys of the cord blood as stimulator. This was the case even in MLR done by using unrelated maternal lys as responder. On the other hand, when in the case of placental eluate, it was found to be greater when compared to serum IgG even where MLR was done using not only B lys but also T lys as stimulator. It is thus strongly suggested that BA include individual specific antibodies against fetal B lys having HLA-D/DR locus determinants in addition to individually nonspecific antibodies common to pregnancy which may be produced to a "yet unknown fetal antigen."