Immune response after vaginal application of antigens in the rhesus monkey.

The immune response after vaginal application of antigens was investigated in six sexually mature female rhesus monkeys. Two model antigens, i.e., lipopolysaccharide (LPS) OF Salmonella typhosa and abortive type T-4 coliphages were applied with or without adjuvant. A plastic sponge used as the antigen carrier was introduced into the upper vagina and placed against the ectocervix. For primary immunization, each monkey received 18 vaginal antigen applications and 10 applications for each booster course. For comparison, three other female rhesus monkeys were immunized systemically. Alum or LPS was used as adjuvant. Blood was obtained two times and cervical mucus three times weekly from each monkey. Antibodies were only barely detectable in cervical mucus after the primary vaginal immunization. However, booster treatments resulted in definite antibody responses. Specific antibodies were also detected in the circulating blood after vaginal booster immunization. The antibody level in cervical secretion in three of four cases was higher than that in circulatin blood. Systemic immunization resulted in high levels of circulating antibodies, but less than 10% appeared in cervical secretions. A characteristic decrease in antibody levels in cervical mucus was usually observed at midcycle after local immunization as well as after systemic immunization. More than 90% of T-4 coliphages applied vaginally were absorbed within 48 hours. Although alum appeared to retard the absorption of antigens, it seemed to enhance the local response. More than 90% of the antibodies to the T-4 coliphages could be removed from the serum and cervial mucus by treatment with anti-immunoglobuin G antiserum. The lymphocyte response to antigens was studied by measuring the 3H-thymidine uptake by peripheral blood lymphocytes in culture. A positive response was observed in three of three systemically immunized and in only two of six locally immunized aminals. In general, the immune response was significantly weaker after local vaginal immunization than after systemic immunization.