Anti-pneumococcal capsular polysaccharide antibody response and CD5 B lymphocyte subsets

摘要

The role of the CD19(+)CD5(+) and CD19(+)CD5(-) B-cell subpopulations in the antibody response to pneumococcal capsular polysaccharides (caps-PS) is controversial. In the present study we evaluated the role of the human CD19(+)CD5(+) and CD19(+)CD5(-) cell populations in the serotype-specific antibody response to caps-PS. After vaccination of 5 healthy human adults with Pneumovax® (PPV23), IgG anti-caps-PS serotype 4 antibody producing cells mainly resided in the CD19(+)CD5(-) B cell subset, as assessed by ELISpot analysis. Moreover, in a humanized SCID mice model, CD19(+)CD5(-) B cells were more effective than CD19(+)CD5(+) cells to produce IgG anti-cap-PS antibodies. Finally, an association was found between the level of IgG anti-caps-PS antibodies and the number of CD19(+)CD5(-) B cells in 33 humans vaccinated with PPV23. Taken together, our data suggest that CD5 defines a functionally distinct population of B cells in humans in the anti-caps-PS immune response.