Development of antibodies against tetravalent meningococcal polysaccharides in revaccinated complement-deficient patients

Individuals deficient in C3 or a late complement component are susceptible to recurrent meningococcal infections. Since they experience meningococcal episodes mostly with uncommon meningococcal serogroups, vaccination with a tetravalent vaccine containing A, C, Y and W135 polysaccharides has been su ggested. We vaccinated a cohort of two C3 and 17 late complement component- deficient (LCCD) patients, revaccinated them 7 years later and investigated the development of their IgG antibodies to the capsular polysaccharides of the meningococcal vaccine. Seven years after the first vaccination levels of IgG antibodies declined compared with the levels present at 6 months aft er the first vaccination, but were still at least four times higher than be fore vaccination. Levels of antibodies to Y polysaccharide in serum of comp lement-deficient patients were rather low but they did not differ significa ntly from those in serum of healthy non-related controls (P = 0.07). Three months after the second vaccination IgG antibodies against all polysacchari des increased, exceeding those measured at 6 months after the first vaccina tion. In the 8 years of observation after the first vaccination two new men ingococcal infections with strains related to the vaccine (serogroup Y stra ins) occurred in two patients, 3.5 and 5 years after the first vaccination. Our findings show that high IgG antibody levels against the tetravalent me ningococcal polysaccharide vaccine were reached after revaccination of two C3 and 17 LCCD individuals 7 years after the first vaccination. Whether rev accination should be required within a period shorter than 7 years is discu ssed, since two vaccinees developed meningococcal disease to vaccine serogr oup Y.