10-valent pneumococcal non-typeable Haemophilus influenzae protein-D conjugate vaccine (PHiD-CV) induces memory B cell responses in healthy Kenyan toddlers

Abstract

Memory B cells are long-lived and could contribute to persistence of humoral immunity by maintaining the plasma-cell pool or making recall responses upon re-exposure to an antigen. We determined the ability of a pneumococcal conjugate vaccine to induce anti-pneumococcal memory B cells. Frequencies of memory B cells against pneumococcal capsular polysaccharides from serotypes 1, 6B, 14, 19F and 23F were determined by cultured B cell enzyme-linked immunospot (ELISPOT) in 35 children aged 12–23 months who received pneumococcal non-typeable Haemophilus influenzae protein-D conjugate vaccine (PHiD-CV). The relationships between plasma antibodies and memory B cell frequencies were also assessed. After two doses of PHiD-CV, the proportion of subjects with detectable memory B cells against pneumococcal capsular polysaccharides increased significantly for serotypes 1 (3–45%; P < 0·01), 19F (21–66%; P < 0·01) and 23F (13–36%; P = 0·02), but not serotypes 6B (24–42%; P = 0·24) and 14 (21–40%; P = 0·06). Correlations between antibodies and memory B cells were weak. Carriage of serotype 19F at enrolment was associated with poor memory B cell responses against this serotype at subsequent time-points (day 30: non-carriers, 82% versus carriers, 0%, P < 0·01; day 210: non-carriers, 72% versus carriers, 33%, P = 0·07). PHiD-CV is capable of inducing memory B cells against some of the component pneumococcal capsular polysaccharides.

Pneumococcal Vaccine Response After Exposure to Parasites in Utero, in Infancy, or Mid-Childhood

“…Others have evaluated infant B cell memory responses to decavalent pneumococcal vaccine in Kenya, finding that response to 19 F was the most robust of all the serotypes, but it was the most common nasopharyngeal colonizing serotype in that community. 32 In our study, preimmunity was the strongest predictor of a strong vaccine response to any given pneumococcal antigen, but we did not find an association with concurrent nasopharyngeal colonization.…”

B Cells and B Cell Blasts Withstand Cryopreservation While Retaining Their Functionality for Producing Antibody

“…Using this approach, not only the frequency of these cells can be established within peripheral blood mononuclear cells (PBMC) revealing the extent of their clonal sizes, but the assay is also suited to reveal the antibody classes and subclasses that these B cells produce, providing insights into the effector functions of B cell memory. While tetramers and other multimers can be used for the detection and study of rare antigen-specific T cells in PBMC [ 13 ], ELISPOT has been the primary approach for B cell immune monitoring and has been used to assess B cell memory in various antigenic and pathogenic systems [ 14 , 15 , 16 , 17 ].…”

Immunogenicity and impact on nasopharyngeal carriage of a single dose of PCV10 given to vietnamese children at 18 months of age

“…[26] In Kenyan toddlers 12-23 months of age, a single dose of PCV10 generated higher Bmem one month after vaccination for serotypes 1 and 19F. [29] Although we did not assess Bmem levels at their peak (seven days post-vaccination), we were still able to observe an increase in Bmem numbers after six months for all vac-cine serotypes tested in the PCV10 group that was not seen in the unvaccinated group. This suggests that a single dose of PCV10 induces immunological memory responses that are likely to be protective for up to six months post-vaccination.…”