Reduced number of transitional and naive B cells in addition to decreased BAFF levels in response to the T cell independent immunogen pneumovax.sup.[R]23

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From: PLoS ONE(Vol. 11, Issue 3)
Publisher: Public Library of Science
Document Type: Report
Length: 8,943 words
Lexile Measure: 1390L

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Abstract :

Protective immunity against T cell independent (TI) antigens such as Streptococcus pneumoniae is characterized by antibody production of B cells induced by the combined activation of T cell independent type 1 and type 2 antigens in the absence of direct T cell help. In mice, the main players in TI immune responses have been well defined as marginal zone (MZ) B cells and B-1 cells. However, the existence of human equivalents to these B cell subsets and the nature of the human B cell compartment involved in the immune reaction remain elusive. We therefore analyzed the effect of a TI antigen on the B cell compartment through immunization of healthy individuals with the pneumococcal polysaccharide (PnPS)-based vaccine Pneumovax.sup.® 23, and subsequent characterization of B cell subpopulations. Our data demonstrates a transient decrease of transitional and naïve B cells, with a concomitant increase of IgA.sup.+ but not IgM.sup.+ or IgG.sup.+ memory B cells and a predominant generation of PnPS-specific IgA.sup.+ producing plasma cells. No alterations could be detected in T cells, or proposed human B-1 and MZ B cell equivalents. Consistent with the idea of a TI immune response, antigen-specific memory responses could not be observed. Finally, BAFF, which is supposed to drive class switching to IgA, was unexpectedly found to be decreased in serum in response to Pneumovax.sup.® 23. Our results demonstrate that a characteristic TI response induced by Pneumovax.sup.® 23 is associated with distinct phenotypical and functional changes within the B cell compartment. Those modulations occur in the absence of any modulations of T cells and without the development of a specific memory response.

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Gale Document Number: GALE|A453451724