Specific-antibody-secreting cells in the rectums and genital tracts of nonhuman primates following vaccination.

To determine optimal strategies to induce specific-antibody-secreting cells (specific ASC) in the rectal and vaginal mucosae, we immunized monkeys with a prototype mucosal immunogen, cholera toxin (CT), given locally or via gastric or parenteral administration. Repeated rectal or vaginal CT immunizations induced strong mucosal and systemic ASC responses. The mucosal responses were, however, confined to the immunization sites and comprised high levels of both specific antitoxin immunoglobulin A (IgA) and IgG. Large numbers of specific IgA and IgG ASC were detected in cell suspensions from dissociated genital and rectal tissues, demonstrating local accumulation of effector B cells at these sites. Intragastric immunization with CT did not per se give rise to cervicovaginal or rectal ASC responses but did prime for a rectal IgA ASC response to local booster immunization. Both rectal and vaginal immunizations also induced circulating blood IgG ASC and IgA ASC. In conclusion, these results show that local administration of antigen to the rectal or vaginal mucosa results in higher ASC responses than systemic or distant mucosal delivery. Furthermore, both the vaginal and the rectal mucosae can serve as inductive sites for systemic ASC responses. These observations should be relevant to the development of vaccines against sexually transmitted diseases such as that caused by human immunodeficiency virus.