Suppression of humoral antibody response during pregnancy in mice

Fifty female BALB/cA mice were allocated to four groups. The mice of groups 1 and 3 were mated with male BALB/cA mice, whereas groups 2 and 4 served as unmated control groups. The mice of groups 1 and 2 received a primary immunization (100 micrograms ovalbumin in Freunds Complete Adjuvant) and the first booster immunization (100 micrograms ovalbumin in sterile saline) prior to mating. Eight days after mating, the mice of groups 1 and 2 received the second booster immunization. The mice of groups 3 and 4 received the primary immunization ten days after mating in group 3 and one booster injection five days later. At the end of the immunization period the individual serum titres of precipitating antibodies against ovalbumin were determined using a line-immunoelectrophoretic assay. Groups 1 and 2 showed no significant difference in the titres of precipitating antibodies against ovalbumin, indicating that the secondary antibody response was not generally suppressed during pregnancy. However, the pregnant mice of group 3 produced significantly lower titres of precipitating antibodies against ovalbumin as compared with the control mice of group 4 (P less than 0.01), demonstrating a suppression of the primary antibody response during pregnancy.