Antigenic stimulation and blocking of pregnancy in mice by an anti-idiotypic antibody to progesterone.

PROBLEM

The present study was carried out to see if the anti-idiotypic (anti-Id) antibody (Ab2) to progesterone could mimic the immunogenicity of the steroid hormone by giving rise to antiprogesterone antibodies (Ab3) and whether these antiprogesterone antibodies (Ab3) were biologically active.

METHOD

Twenty virgin female Balb/C mice were actively immunized with the anti-Id antibody (Ab2). The antiprogesterone antibody (Ab3) titres in the serum were determined and the animals were used for fertility studies. In the passive immunization studies Balb/C female mice were injected i.p. with 100 micrograms of anti-Id antibody to see its effect on pregnancy.

RESULTS

The actively immunized animals when mated showed 80% reduction in their fertility rate. The duration of infertility (20-121 days) in these animals could be directly correlated with the concentration of antiprogesterone antibody (Ab3). The anti-Id antibody (Ab2) blocked pregnancy in 80% of the passively immunized mice.

CONCLUSION

The studies show that anti-Id antibody to progesterone could mimic the immunogenicity of progesterone and give rise to antiprogesterone antibodies (Ab3). The anti-Id antibody successfully blocked pregnancy in mice both after active and passive immunization.