Anti-Mac-1 antibodies and early pregnancy loss in mice

This study focused on the role of adhesion molecules in early pregnancy in mice. Injection of anti-Mac-1 antibodies during early pregnancy resulted in early pregnancy loss (only 30.7% of mice in the group injected with anti-Mac-1 antibody were pregnant compared with 87.5% of controls), while mice treated with anti-Mac-1 antibodies during late pregnancy did not show a significant abortive effect (68.8% mice in the treated group were pregnant compared with 92.9% of control mice). Anti-LFA-1 alpha, LFA-1 beta or mouse Ag-Eb antibodies, when injected during early pregnancy, caused a nonsignificant decrease in pregnancy rate ranging between 15% and 25% (P > 0.05), while anti-Thy-1.2 antibodies demonstrated a marginal effect only. Staining of uterine tissue sections, collected on days 4-6 of pregnancy, with anti-Mac-1 antibodies, demonstrated antibody bound to cells in the deep endometrium and in the myometrium but not in the uterine area close to the lumen or on the surface of the blastocyst. These results indicate a possible role for the Mac-1 antigen in early pregnancy.