Allogeneic matings and immunization have different effects on nulliparous and multiparous mice

Area of Science:

• Reproductive immunology
• Immunogenetics
• Maternal-fetal interactions

Background:

• CBA/J female mice exhibit high spontaneous fetal loss when mated with DBA/2 males.
• Immunization with C57BL leukocytes, but not DBA/2 leukocytes, reduces fetal resorption rates.
• Previous studies established the efficacy of specific leukocyte immunization in mitigating early pregnancy loss.

Purpose of the Study:

• To investigate the long-term effects of immunization on subsequent pregnancies.
• To determine if continued immunization impacts fetal resorption rates in second pregnancies.
• To assess the influence of immunization on the sex ratio of offspring.

Main Methods:

• CBA/J female mice were immunized with C57BL or DBA/2 leukocytes during their first pregnancy.
• Subsequent pregnancies were monitored for fetal resorption rates and offspring sex ratios.
• Unimmunized CBA/J females mated with DBA/2 males served as controls.

Main Results:

• Second pregnancies in unimmunized females showed low fetal resorption rates.
• Continued immunization in multigravid, multiparous mice was linked to increased late-onset fetal resorptions.
• No significant shift in sex ratio was observed between treated and untreated pregnancies.

Conclusions:

• Untreated CBA/J females can develop immunity to trophoblast antigens during first pregnancies, leading to normal reproductive outcomes in subsequent pregnancies.
• Persistent leukocyte immunization, regardless of source, may increase fetal wastage in later pregnancies.
• Chronic immunization with male leukocytes does not alter the sex ratio of viable offspring, suggesting potential applications for immunotherapy in recurrent spontaneous abortions.