Systemic immunity developing from intrauterine antigen exposure in the nonpregnant rat

This report provides a simplified model for investigating the antigen handling mechanisms of the mammalian uterus. The effectiveness of the uterus as a site for systemic immunization has been studied using a hapten-protein conjugate (DNP-BGG) as antigen in nonpregnant virgin rats. The data indicate that although the uterus is inefficient as an antigen delivery site, strong systemic immune responses can be generated under appropriate conditions. Intrauterine (i.u.) immunization with alum-precipitated DNP-BGG did not induce significant antibody activity but primed the females so that vigorous anamnestic responses were produced after a second exposure to (soluble) antigen. The following results were obtained: (1) The optimal immunization dose was 100-2000 micrograms. (2) Alum-precipitation of the immunizing antigen was necessary in order to sensitize the female, while inclusion of killed Bordetella pertussis organisms was not. (3) The site of challenge after i.u. immunization affected the level of serum antibody activity. (4) Retention of antigen within the uterus for as little as 1 day sensitized the females as effectively as 28 days' exposure. (5) The presence or absence of ovarian hormones had no apparent effect in this system.