DIFFERENTIAL KINETICS AND DISTRIBUTION OF ANTIBODIES IN SERUM AND NASAL AND VAGINAL SECRETIONS AFTER NASAL AND ORAL VACCINATION OF HUMANS

Although nasal vaccination has emerged as an interesting alternative t o systemic or oral vaccination, knowledge is scarce about the immune r esponses after such immunization in humans. In the present study, we h ave compared the kinetics and organ distribution of the antibody respo nses after nasal and oral vaccination. We immunized female volunteers nasally or orally fifth cholera toxin B subunit (CTB) and determined t he specific antibody levels in serum and nasal and vaginal secretions, as well as the number of circulating antibody-secreting cells, before immunization and 1, 2, 3, 6, and 26 weeks thereafter. Nasal vaccinati on induced 9-fold CTB-specific immunoglobulin B (IgA) and 56-fold spec ific IgG antibody increases in nasal secretions, whereas no significan t IgA increase was seen after oral vaccination. Both oral and nasal va ccination resulted in 5- to 6-fold CTB-specific IgA and 20- to 30-fold specific IgG increases in vaginal secretions. Strong serum responses to CTB were also induced by both routes of vaccination. A notable diff erence between nasal and oral vaccination was that the nasal route eli cited a specific antibody response with a later onset but of much long er duration than did the oral route. We conclude from this study that the nasal route is superior to the oral route for administering at lea st nonliving vaccines against infections in the upper respiratory trac t, whereas either oral or nasal vaccination might be used for elicitin g antibody responses in the female genital tract.