During the gestational cycle the placental tissue does not express class II MHC antigens and
whether this phenomenon is important to fetal survival has not yet been evoked. It has been
reported that class II antigen expression precedes renal and cardiac graft rejection, which
may also be the case in fetal abortion. In a recent report we showed that placental cells can
be induced to express class II antigens in vitro and that these cells undergo different
regulatory mechanisms depending on their anatomical position in the placenta. Thus …