Foreign fetal cells persist in the maternal circulation

Area of Science:

• Reproductive immunology
• Fetal cell microchimerism
• Transplant immunology

Background:

• Donor egg pregnancies involve the transfer of allogenic fetal cells into the maternal circulation.
• The persistence and immune implications of these cells are not fully understood.

Purpose of the Study:

• To investigate the long-term persistence of allogenic fetal cells in maternal circulation following donor egg pregnancies.
• To explore potential mechanisms of immune evasion by these persistent fetal cells.

Main Methods:

• Nested polymerase chain reaction (PCR) was used to detect the DYS14 sequence (Y chromosome marker).
• DNA was purified from peripheral blood cells of women who had donor egg pregnancies with male or female offspring.
• A control group of women with female offspring was included to rule out non-fetal sources of male DNA.

Main Results:

• The DYS14 sequence was detected in 45% of women with previous donor egg pregnancies resulting in male offspring.
• No detection of the DYS14 sequence was observed in women with donor egg pregnancies resulting in female offspring.
• Fetal cell DNA was detected up to 9 years after delivery in some participants.

Conclusions:

• Allogenic fetal cells from donor egg pregnancies can persist in maternal circulation for at least 9 years.
• These persistent cells may evade maternal immune detection through an unknown mechanism.
• The findings have implications for understanding immune tolerance and potential applications in regenerative and transplant medicine.