Primary and booster mucosal immune responses to meningococcal group A and C conjugate and polysaccharide vaccines administered to university studentsin the United Kingdom

Meningococcal group A+C capsular polysaccharide (PS) conjugate vaccines may prime for serum immunoglobulin G (Igc) memory responses to meningococcal c apsular PS, It is not known whether these vaccines induce immunological mem ory at the mucosal level, which may be important in reducing nasopharyngeal carriage, Mucosal immune responses to meningococcal conjugate and PS vacci nes in young adults were investigated. Healthy university students were ran domized to receive either a groups A+C meningococcal conjugate vaccine (MAC conj, n = 100) or a group A+C meningococcal PS vaccine (MACPS, n = 95), One year after the primary immunization, both groups were randomized again to receive a MACconj or a MACPS booster vaccination, Saliva samples were colle cted before and I month after the primary and booster vaccinations. Anti-me ningococcal A (MenA) and C (MenC) PS IgA and IgG antibody Levels were measu red by a standard enzyme-linked immunosorbent assay. After the primary vacc ination, salivary MenA and MenC IgG and MenA IgA concentrations were signif icantly increased after immunization with both MACconj and MACPS vaccines, but the salivary Men C IgA level was increased only after MACPS vaccine (P < 0.01), IgA responses to both serogroups were greater for MACPS than MACco nj vaccine (P < 0.05), whereas no significant differences were seen for IgG responses, MenA Ige titers were higher after the MACPS booster in MACconj- primed subjects than after the MACPS primary vaccination, suggesting the pr esence of IgG memory. Antibody responses to a dose of either MACPS or MACco nj were not significantly reduced in those previously given MACPS compared to the primary responses to those vaccines. Meningococcal A+C conjugate and PS vaccines induce significant mucosal responses in young adults. MACconj priming may induce IgG memory at the mucosal level, which is likely to he a reflection of an anamnestic serum Ige response. No evidence of mucosal hyp oresponsiveness was observed after MACPS priming in this study.