Conclusion
Comparable increases in opsonophagocytic titers between study groups A and B concomitant with a comparable rise in PPS-specific IgM memory B cells indicate revaccination to be beneficial regardless of the degree of CD4 T cell reconstitution. These findings emphasize the importance of defining effective vaccination practices amongst high-risk individuals.
Methods
We assessed antibody levels, opsonophagocytic activity and phenotype of pneumococcal polysaccharide (PPS) specific-B cells post-revaccination in long term HAART cohorts stratified according to CD4 count as group A (CD4>200) and group B (CD4<200). Anti-PPS IgG, IgM and functional antibody response against vaccine serotypes 14 and 23F were measured by ELISA and opsonophagocytic assay followed by phenotypic analysis of PPS14 and 23F-specific B cells using fluorescently labeled PPS.
Results
Significant increases in total and functional antibody titers were noted in groups A and B post-vaccination concomitant with significant rise in PPS-specific IgM memory B cells, a critical B cell subset required for protection against PPS although the overall response remained significantly diminished compared to HIV-negative volunteers.