Demonstration of immunoreactive eosinophil granule major basic protein in the plasma and placentae of non-human primates.

A protein immunologically identical to the major basic protein (MBP) of eosinophil granules is present in the plasma of pregnant women and has been localized to human placental X cells using immunofluorescence. This study demonstrates the presence of similar immunoreactive molecules in the placental X cells from several non-human primates. We also describe the presence of increased plasma levels of MBP in the pregnant gorilla and in pregnant cynomolgus and rhesus monkeys as compared to non-pregnant counterparts. Such findings suggest that non-human primates are a suitable animal model for the study of the X cell function and in particular the physiological importance of MBP in pregnancy.