Abstract

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

Muema DM, Nduati EW, Uyoga M, Bashraheil M, Scott JA, Hammitt LL, Urban BC
Clin Exp Immunol. 2015;181

Permenent descriptor
https://doi.org/10.1111/cei.12637


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.