Macrophage activity in mouse pregnancy

Antigen handling and clearance by macrophages during mouse pregnancy has been examined by monitoring blood levels of 125I-labelled polyvinyl pryrrolidone (PVP) at different times following its intravenous injection into mated females. PVP clearance is significantly reduced between days 12 and 14 of pregnancy in both syngeneic and allogeneic matings. No significant differences were observed between virgin and mated females at earlier or later states of pregnancy. The findings are discussed in relation to the possible role of macrophages in the immunoregulatory processes involved in the maintenance of the foetus as an intrauterine allograft.