Localization of a molecule immunochemically similar to eosinophil major basic protein in human placenta

Area of Science:

• Reproductive biology
• Immunology
• Biochemistry

Background:

• Human pregnancy exhibits a significant increase in eosinophil major basic protein (MBP) immunoreactivity in maternal blood.
• The source of this elevated MBP during gestation has not been definitively identified.

Purpose of the Study:

• To investigate the cellular source and characteristics of major basic protein (MBP) detected during human pregnancy.
• To determine if placental tissue contributes to the elevated MBP levels observed in maternal circulation.

Main Methods:

• Immunofluorescence staining of placental tissue to detect MBP.
• Analysis of placental cyst fluid and maternal serum using Sephadex G-50 chromatography.
• Comparison of gestational MBP with MBP from hypereosinophilic syndrome patients.

Main Results:

• Placental tissue, specifically X cells and giant cells, showed specific binding of anti-MBP antibodies.
• No infiltrating eosinophils were detected in the placenta.
• Placental cyst fluid contained immunoreactive MBP at concentrations significantly higher than maternal blood.
• Gestational MBP molecules were chromatographically larger than MBP from eosinophils.

Conclusions:

• The placenta, particularly placental X cells, is the likely source of the major basic protein (MBP) detected during human pregnancy.
• The elevated MBP in maternal blood during pregnancy is not derived from infiltrating eosinophils but from placental production.