Secretory immune responses in mouse vaginal fluid after pelvic, parenteral or vaginal immunization.

Intravaginal immunization causes IgA responses in vaginal fluid, but so far lymphoid nodules in mouse vaginal mucosa have not been detected. The present study was therefore designed to test the hypothesis that IgA responses in the female reproductive tract may be generated in the regional iliac lymph nodes. Two, non-mucosal sites were identified in the female mouse pelvis, the subserous and presacral spaces, from which lymph drains mainly to the iliac nodes. Immunization at these pelvic sites with horse ferritin adsorbed to aluminum hydroxide (AH) caused much higher IgA and IgG titres in vaginal fluid than intravaginal immunization; moreover, the pelvic immunizations caused significantly higher and better sustained IgA titres in vaginal fluid than subcutaneous immunization near the scapulae or in the perineum, while IgG titres in vaginal fluid were similar in these groups. Additional mice were immunized with ferritin subcutaneously near the scapulae or in the presacral pelvic space using dimethyl dioctadecyl ammonium bromide (DDA), AH plus muramyl dipeptide, or the Ribi adjuvant system as adjuvants. Pelvic immunization caused higher IgA titres in vaginal fluid than subcutaneous immunization in each case. The IgA response stimulated by DDA was similar to that produced by AH but higher than the responses caused by the other two adjuvants, while IgG titres were similar with all four adjuvants in both sites. The results suggest that non-mucosal, pelvic immunization is particularly effective in stimulating IgA responses in the female reproductive tract. The observation is consistent with the possibility that the iliac lymph nodes may play a role in the development of IgA responses in the reproductive tract.