Meningococcal serogroup C polysaccharide specific memory B cells, directly enumerated by labeled polysaccharide, are not affected by age at vaccination

The influence of age on the generation and persistence of specific memory B cells after vaccination with Neisseria meningitidis type C polysaccharide (MenC-PS) conjugate is unknown. MenC-PS-specific B cells could be directly enumerated by fluorochrome-labeled MenC-PS and flow cytometry in blood up to at least 4 years after vaccination, ranging from 0.01% to 0.78% of total B cells and did not correlate with age at vaccination. The percentage of MenC-specific memory B cells out of total memory B cells correlated with total MenC-specific B-cells and with frequencies of IgA+ plus IgG+ MenC-specific AbSC, but not with MenC-specific Ab.